Recent studies of diabetes suggest an obesity paradox: mortality risk increases with weight in people without diabetes but decreases with weight in people with diabetes. A recent study also reports the paradox more generally with health care utilization. Whether this paradox in health care utilization and spending is causal or instead the result of empirical biases and confounding factors has yet to be examined in detail. This study set out to examine changes in the relationship between BMI and health care expenditures in populations with versus without diabetes, controlling for confounding risk factors. It found that the obesity paradox does not exist and is the result of statistical biases such as confounding and reverse causation. Obesity is not cost-saving for people with diabetes. Thus, insurers and physicians should renew efforts to prevent obesity in people with diabetes.

BMI is positively associated with mortality in the general population (15) and with the risk of developing type 2 diabetes and other diseases (e.g., cardiovascular disease [CVD], hypertension, coronary artery disease, stroke, and heart failure) (612). Obesity accounts for 80–85% of the overall risk of type 2 diabetes (13). However, among people with type 2 diabetes, numerous studies (12,1420) have shown a reduction in mortality risk among those with overweight and obesity compared with those of normal weight, a phenomenon often called the “obesity paradox.” The coronavirus disease 2019 (COVID-19) pandemic has renewed interest in the obesity paradox because both obesity and diabetes are significant predictors of mortality from COVID-19, and any accurate prediction model requires one to take into account the interaction between obesity and diabetes (i.e., the obesity paradox).

One explanation for the obesity paradox is the failure to address confounding variables and reverse causation biases in studies of the relationship between obesity and the risk of mortality (21). For example, because smoking is negatively associated with BMI and positively associated with the risk of mortality, appropriate analytical adjustment for the confounding effect of smoking status is important (22). Some chronic diseases such as cancer can lead to both weight loss and elevated risk of death (2326), thus, leading to an underestimation of the effect of weight on mortality risk (i.e., reverse causation). Another explanation is that diabetes among people without obesity may be the result of a different and possibly more severe disease process (e.g., CVD) (14). If these factors are not accounted for, one can expect to see what appears to be an obesity paradox in mortality data.

A recent article extended the obesity paradox from mortality to morbidity (27). It found an obesity paradox in terms of health care expenditures; compared with people of normal weight, people with obesity were found to have average total health care expenditures that were significantly lower if they had diabetes and nonsignificantly higher if they did not have diabetes. This expenditure paradox may again be the result of a failure to control adequately for confounding biases.

In this article, we revisit the obesity paradox for expenditures using the same Medical Expenditure Panel Survey (MEPS) data (27), but updated for the years 2008–2016. Our study built on the previous study in the following way to control for possible confounding: 1) we restricted our study to people with type 2 diabetes; 2) we designated people as having diabetes who reported not having it in the main survey but reported having it in the MEPS diabetes care survey (DCS), a self-administered supplement survey; and 3) we excluded from our expenditure analyses women with gestational diabetes mellitus (GDM), smokers, and people with cancer or CVD diagnoses. In this cleaner sample of diabetes cases, we found no obesity paradox in expenditures.

Data Sample

The MEPS is a nationally representative, annual survey sponsored by the Agency for Healthcare Research and Quality. A new panel is introduced every year, and people in each panel are followed for 2 years. Every year, the survey interviews about 15,000 households to get a nationally representative sample of the civilian, noninstitutionalized U.S. population. It collects information on health status, health insurance coverage, and health care utilization and expenditures for each household over the course of 2 years.

Our study used MEPS data for the years 2008–2016, which yielded data on 210,797 people with a positive survey weight and a valid BMI value (>0). Our analytic sample included people who either were never diagnosed with diabetes or were diagnosed with type 2 diabetes; we excluded 1) those who were taking only insulin and were <30 years of age at the time of diabetes diagnosis (n = 469) and 2) those who reported being pregnant and who were diagnosed with diabetes during the survey year (n = 11). A total of 210,317 individuals remained in our analytical sample. For additional analyses, we excluded those who had ever been smokers and those who had ever been diagnosed with cancer or cardiovascular diseases (i.e., myocardial infarction [MI], angina, coronary heart disease [CHD], stroke, or other heart disease) (32% of the sample). The sample for additional analyses thus included 142,551 individuals. From this point onward, we will refer to the analytical sample as the ANS sample and the sample for additional analyses as the ADS sample.

Measures

Health Care Utilization

We used the seven health care utilization measures listed below, adjusted for inflation.

  • Total health care expenditures ≥$0. This includes all health care expenditures, including expenditures for prescription medicines

  • Combined expenditures, category 1 ≥$0 (Expense1). All expenditures for inpatient discharges, prescription medicines, emergency department visits, and visits to physicians in offices and outpatient departments

  • Combined expenditures, category 2 ≥$0 (Expense2). All expenditures for inpatient discharges, prescription medicine, emergency department visits, and visits to all office-based providers in offices (OBD) and outpatient departments (OP)

  • Emergency room (ER) visit expenditures ≥$0. Facility and physician expenditures for visits to emergency departments

  • Expenditure for inpatient stays ≥$0. Facility and physician expenditures for all hospital inpatient discharges

  • All OBD visit expenditures ≥$0. Expenditures for visits to office-based health care providers, including physicians and nonphysicians

  • All outpatient visit expenditures ≥$0. Facility and provider expenditures for OP visits

Health Status and Sociodemographics

We used BMI to categorize individuals’ weight using five dummy variables—underweight: BMI <20 kg/m2, normal weight: BMI 20 to <25 kg/m2, overweight: BMI 25 to <30 kg/m2, obese: BMI 30 to <35 kg/m2, and severely obese: BMI ≥35 kg/m2. Diabetes was self-reported either in the MEPS household survey or the MEPS DCS. We used individuals’ age in years and reported smoking status as a dummy variable.

Individuals’ health insurance status was indicated via dummy variables: any private insurance (without non-Medicare public insurance), Medicare insurance only, any public insurance (with or without Medicare or private insurance), and uninsured. Private coverage meant covered by private third parties or Tricare (uniformed services insurance program). A five-category variable controlled for individuals’ education in terms of years of education. Education categories were postgraduate (>16 years), college graduate (16 years), some college (13–15 years), high school graduate (12 years), and less than high school (<12 years). Other indicator variables included seven self-reported chronic conditions, including hypertension, asthma, stroke, emphysema, CHD, cancer, and MI; sex; race/ethnicity, including Asian, Hispanic, African American, and Non-Hispanic other races; household income level as percentage of the federal poverty level, including ≥200, 125 to <200, 100 to <125, or <100%; and census region, including West, Midwest, South, and Northeast. We accounted for year-specific fixed effects by using an indicator variable for each data year.

Statistical Analysis

This study used Stata SE, v. 15.1, statistical software (Stata Corporation, College Station, TX) to predict health care expenditures accounting for the MEPS complex survey design. Our analyses examined how the association between BMI and each of the seven health care expenditure measures varied with diabetes status.

Analyses used a two-part model because of highly skewed expenditures. Logistic regression predicted the likelihood of individuals to have positive expenditures. Generalized linear regression using a γ distribution and log link predicted the expenditures among those with positive expenditures. Using combined estimates from the two parts for each type of health care utilization, we used the Stata margin command to predict expenditures and marginal effects by BMI and diabetes status at sampled values of all other predictors. We compared differences in health care expenditures between individuals with and without diabetes within the same BMI category. We also compared differences in health care expenditures between individuals with normal weight and those in other weight categories separately for people with and without diabetes. In addition, we compared the difference observed between any two BMI categories among people with diabetes with the difference observed between the same two BMI categories among individuals without diabetes. We refer to this comparison as the “difference-in-differences estimate.”

In all of the models, we also included interactions of diabetes status with the BMI categorical variable, as well as age. We predicted expenditures separately for individuals in both samples: ANS (excluding those with type 1 diabetes or GDM) and ADS (all in the ANS sample excluding current smokers and individuals with cancer or cardiovascular disease).

Table 1 presents demographic characteristics of the ANS and ADS samples. In the ANS sample, there were 210,317 adults ≥18 years of age with a positive survey weight in the MEPS consolidated public use files for years 2008–2016. A total of 21,532 were diagnosed with type 2 diabetes, and the rest had no diabetes diagnosis history (Table 1). Compared with people with type 2 diabetes, people with no diabetes diagnosis were younger and more likely to be male and non-Hispanic other or Asian, have higher household income and education, have any private insurance (private or private with Medicare) or no insurance, reside in the West or Northeast region, and have a BMI in the overweight category or lower. They were less likely to be a smoker or to be diagnosed with any of the seven chronic diseases. In each of the seven expenditure measures, individuals with type 2 diabetes had average health care expenditures higher than those who were never diagnosed for diabetes. Those reporting that they had no cancer and that they were not a current smoker had relatively lower utilization levels for each of the six health care provider types. Average utilization of five of the six provider services was higher among older versus younger adults.

TABLE 1

Characteristics of the Study Sample

CharacteristicsRespondents (Excluding People With Type 1 Diabetes or GDM)
Excluding Smokers and People With Cancer or CVD
All
(N = 210,317)
With Diabetes
(N = 21,532 [10.2%])
Without Diabetes
(N = 188,785 [89.8%])
All
(N = 142,551)
With Diabetes
(N = 10,437 [7.3%])
Without Diabetes
(N = 132,114 [92.7%])
Age, years, mean (SE) 46.8 (0.2) 61.6 (0.2) 45.3 (0.18) 42.8 (0.1) 57.8 (0.2) 41.7 (0.1) 
Female, % (SE) 51.4 (0.2) 50.1 (0.6) 51.6 (0.2) 52.3 (0.2) 51.4 (0.9) 52.4 (0.2) 
Family income as a percentage of FPL, % (SE)
≥200%
125 to <200%
100 to <125%
<100% 


70.5 (0.5)
13.3 (0.2)
4.2 (0.1)
12.0 (0.3) 


63.1 (0.8)
16.4 (0.4)
6.0 (0.2)
14.5 (0.5) 


71.2 (0.5)
12.9 (0.2)
4.1 (0.1)
11.8 (0.3) 


73.7 (0.5)
12.3 (0.2)
3.7 (0.1)
10.4 (0.3) 


66.9 (0.9)
15.1 (0.5)
5.3 (0.3)
12.7 (0.6) 


74.1 (0.5)
12.1 (0.2)
3.5 (0.1)
10.2 (0.3) 
Education level, % (SE) 5+ years of college
4 years of college
Some college
High school
Less than high school 

9.6 (0.3)
15.8 (0.3)
24.0 (0.2)
25.3 (0.3)
25.4 (0.3) 

6.5 (0.4)
10.0 (0.4)
22.2 (0.6)
29.8 (0.6)
31.6 (0.6) 

9.9 (0.3)
16.4 (0.3)
24.1 (0.2)
24.8 (0.2)
24.8 (0.3) 

10.5 (0.3)
17.8 (0.3)
24.0 (0.3)
22.6 (0.3)
25.1 (0.3) 

7.0 (0.6)
11.3 (0.6)
22.8 (0.8)
28.2 (0.8)
30.7 (0.7) 

10.8 (0.3)
18.3 (0.3)
24.0 (0.3)
22.2 (0.3)
24.7 (0.3) 
Race/ethnicity, % (SE)
Other
Hispanic
Asian
Black 

72.3 (0.8)
12.9 (0.7)
4.6 (0.4)
10.2 (0.5) 

68.7 (1.0)
13.3 (0.9)
4.3 (0.4)
13.7 (0.8) 

72.7 (0.8)
12.9 (0.7)
4.6 (0.4)
9.9 (0.5) 

67.8 (0.9)
15.8 (0.8)
5.9 (0.4)
10.5 (0.5) 

61.7 (1.2)
17.1 (1.1)
6.1 (0.6)
15.1 (0.9) 

68.2 (0.9)
15.7 (0.8)
5.9 (0.4)
10.2 (0.5) 
Health insurance,* % (SE)
Any private
Medicare only
Any public
Uninsured 

66.1 (0.5)
7.4 (0.2)
13.2 (0.4)
13.2 (0.3) 

55.4 (0.7)
17.5 (0.4)
19.9 (0.6)
7.2 (0.3) 

67.2 (0.6)
6.4 (0.2)
12.6 (0.4)
13.8 (0.4) 

70.3 (0.6)
4.5 (0.1)
11.4 (0.3)
13.8 (0.4) 

61.0 (0.9)
12.5 (0.5)
17.0 (0.7)
9.4 (0.5) 

71.0 (0.6)
3.9 (0.1)
11.0 (0.3)
14.1 (0.4) 
Chronic conditions, % (SE)
Hypertension
Asthma
Stroke
Emphysema
CHD
MI
Cancer 

32.9 (0.3)
9.4 (0.1)
3.7 (0.1)
2.2 (0.1)
13.8 (0.2)
3.7 (0.1)
10.5 (0.2) 

77.9 (0.5)
13.4 (0.4)
12.1 (0.4)
5.2 (0.3)
32.7 (0.6)
13.6 (0.4)
18.9 (0.5) 

28.3 (0.3)
9.0 (0.2)
2.8 (0.1)
1.9 (0.1)
11.8 (0.2)
2.7 (0.1)
9.7 (0.2) 

24.4 (0.3)
8.2 (0.2)

0.7 (0.0)


— 

71.1 (0.8)
10.1 (0.5)

1.7 (0.2)


— 

21.2 (0.3)
8.1 (0.2)

0.6 (0.0)


— 
Smoker, % (SE) 15.6 (0.3) 13.8 (0.4) 15.8 (0.3) — — — 
Region
Northeast
Midwest
South
West 

18.1 (0.6)
21.5 (0.6)
37.1 (0.7)
23.3 (0.6) 

17.2 (0.7)
21.4 (0.8)
41.4 (1.0)
20.0 (0.8) 

18.2 (0.6)
21.5 (0.6)
36.6 (0.7)
21.5 (0.7) 

18.4 (0.6)
20.3 (0.6)
36.2 (0.8)
25.1 (0.7) 

16.9 (0.7)
19.8 (0.9)
41.4 (1.1)
22.0 (1.0) 

18.5 (0.6)
20.3 (0.6)
35.9 (0.8)
25.3 (0.7) 
BMI, kg/m2, % (SE)
<20
20 to <25
25 to <30
30 to <35
≥35 

5.5 (0.1)
30.2 (0.3)
34.2 (0.2)
17.9 (0.2)
12.1 (0.2) 

1.5 (0.1)
12.6 (0.4)
30.3 (0.5)
27.2 (0.5)
28.5 (0.6) 

5.9 (0.3)
32.1 (0.3)
34.6 (0.2)
16.9 (0.2)
10.5 (0.2) 

5.6 (0.1)
31.3 (0.3)
34.1 (0.2)
17.4 (0.2)
11.5 (0.2) 

1.0 (0.1)
11.8 (0.5)
29.8 (0.7)
28.4 (0.7)
29.0 (0.7) 

5.9 (0.1)
32.7 (0.3)
34.4 (0.3)
16.7 (0.2)
10.3 (0.2) 
Health care expenditures, $, mean (SE) 
 Total
Expense1§
Expense2‖
ER visits
Inpatient stay
OBD visits
OP visits 
4,847 (54)
3,767 (45)
4,284 (49)
194 (4)
1,301 (28)
1,194 (15)
450 (13) 
11,291 (218)
9,318 (188)
10,242 (202)
311 (10)
3,110 (111)
2,256 (52)
820 (41) 
4,189 (51)
3,201 (41)
3,676 (46)
183 (4)
1,116 (27)
1,086 (15)
412 (13) 
3,197 (42)
2,407 (35)
2,782 (39)
141 (4)
726 (19)
852 (12)
315 (13) 
7,300 (228)
6,076 (212)
6,699 (224)
217 (14)
1,454 (97)
1,547 (62)
608 (64) 
2,915 (42)
2,156 (34)
2,514 (38)
135 (4)
676 (19)
804 (12)
295 (13) 
CharacteristicsRespondents (Excluding People With Type 1 Diabetes or GDM)
Excluding Smokers and People With Cancer or CVD
All
(N = 210,317)
With Diabetes
(N = 21,532 [10.2%])
Without Diabetes
(N = 188,785 [89.8%])
All
(N = 142,551)
With Diabetes
(N = 10,437 [7.3%])
Without Diabetes
(N = 132,114 [92.7%])
Age, years, mean (SE) 46.8 (0.2) 61.6 (0.2) 45.3 (0.18) 42.8 (0.1) 57.8 (0.2) 41.7 (0.1) 
Female, % (SE) 51.4 (0.2) 50.1 (0.6) 51.6 (0.2) 52.3 (0.2) 51.4 (0.9) 52.4 (0.2) 
Family income as a percentage of FPL, % (SE)
≥200%
125 to <200%
100 to <125%
<100% 


70.5 (0.5)
13.3 (0.2)
4.2 (0.1)
12.0 (0.3) 


63.1 (0.8)
16.4 (0.4)
6.0 (0.2)
14.5 (0.5) 


71.2 (0.5)
12.9 (0.2)
4.1 (0.1)
11.8 (0.3) 


73.7 (0.5)
12.3 (0.2)
3.7 (0.1)
10.4 (0.3) 


66.9 (0.9)
15.1 (0.5)
5.3 (0.3)
12.7 (0.6) 


74.1 (0.5)
12.1 (0.2)
3.5 (0.1)
10.2 (0.3) 
Education level, % (SE) 5+ years of college
4 years of college
Some college
High school
Less than high school 

9.6 (0.3)
15.8 (0.3)
24.0 (0.2)
25.3 (0.3)
25.4 (0.3) 

6.5 (0.4)
10.0 (0.4)
22.2 (0.6)
29.8 (0.6)
31.6 (0.6) 

9.9 (0.3)
16.4 (0.3)
24.1 (0.2)
24.8 (0.2)
24.8 (0.3) 

10.5 (0.3)
17.8 (0.3)
24.0 (0.3)
22.6 (0.3)
25.1 (0.3) 

7.0 (0.6)
11.3 (0.6)
22.8 (0.8)
28.2 (0.8)
30.7 (0.7) 

10.8 (0.3)
18.3 (0.3)
24.0 (0.3)
22.2 (0.3)
24.7 (0.3) 
Race/ethnicity, % (SE)
Other
Hispanic
Asian
Black 

72.3 (0.8)
12.9 (0.7)
4.6 (0.4)
10.2 (0.5) 

68.7 (1.0)
13.3 (0.9)
4.3 (0.4)
13.7 (0.8) 

72.7 (0.8)
12.9 (0.7)
4.6 (0.4)
9.9 (0.5) 

67.8 (0.9)
15.8 (0.8)
5.9 (0.4)
10.5 (0.5) 

61.7 (1.2)
17.1 (1.1)
6.1 (0.6)
15.1 (0.9) 

68.2 (0.9)
15.7 (0.8)
5.9 (0.4)
10.2 (0.5) 
Health insurance,* % (SE)
Any private
Medicare only
Any public
Uninsured 

66.1 (0.5)
7.4 (0.2)
13.2 (0.4)
13.2 (0.3) 

55.4 (0.7)
17.5 (0.4)
19.9 (0.6)
7.2 (0.3) 

67.2 (0.6)
6.4 (0.2)
12.6 (0.4)
13.8 (0.4) 

70.3 (0.6)
4.5 (0.1)
11.4 (0.3)
13.8 (0.4) 

61.0 (0.9)
12.5 (0.5)
17.0 (0.7)
9.4 (0.5) 

71.0 (0.6)
3.9 (0.1)
11.0 (0.3)
14.1 (0.4) 
Chronic conditions, % (SE)
Hypertension
Asthma
Stroke
Emphysema
CHD
MI
Cancer 

32.9 (0.3)
9.4 (0.1)
3.7 (0.1)
2.2 (0.1)
13.8 (0.2)
3.7 (0.1)
10.5 (0.2) 

77.9 (0.5)
13.4 (0.4)
12.1 (0.4)
5.2 (0.3)
32.7 (0.6)
13.6 (0.4)
18.9 (0.5) 

28.3 (0.3)
9.0 (0.2)
2.8 (0.1)
1.9 (0.1)
11.8 (0.2)
2.7 (0.1)
9.7 (0.2) 

24.4 (0.3)
8.2 (0.2)

0.7 (0.0)


— 

71.1 (0.8)
10.1 (0.5)

1.7 (0.2)


— 

21.2 (0.3)
8.1 (0.2)

0.6 (0.0)


— 
Smoker, % (SE) 15.6 (0.3) 13.8 (0.4) 15.8 (0.3) — — — 
Region
Northeast
Midwest
South
West 

18.1 (0.6)
21.5 (0.6)
37.1 (0.7)
23.3 (0.6) 

17.2 (0.7)
21.4 (0.8)
41.4 (1.0)
20.0 (0.8) 

18.2 (0.6)
21.5 (0.6)
36.6 (0.7)
21.5 (0.7) 

18.4 (0.6)
20.3 (0.6)
36.2 (0.8)
25.1 (0.7) 

16.9 (0.7)
19.8 (0.9)
41.4 (1.1)
22.0 (1.0) 

18.5 (0.6)
20.3 (0.6)
35.9 (0.8)
25.3 (0.7) 
BMI, kg/m2, % (SE)
<20
20 to <25
25 to <30
30 to <35
≥35 

5.5 (0.1)
30.2 (0.3)
34.2 (0.2)
17.9 (0.2)
12.1 (0.2) 

1.5 (0.1)
12.6 (0.4)
30.3 (0.5)
27.2 (0.5)
28.5 (0.6) 

5.9 (0.3)
32.1 (0.3)
34.6 (0.2)
16.9 (0.2)
10.5 (0.2) 

5.6 (0.1)
31.3 (0.3)
34.1 (0.2)
17.4 (0.2)
11.5 (0.2) 

1.0 (0.1)
11.8 (0.5)
29.8 (0.7)
28.4 (0.7)
29.0 (0.7) 

5.9 (0.1)
32.7 (0.3)
34.4 (0.3)
16.7 (0.2)
10.3 (0.2) 
Health care expenditures, $, mean (SE) 
 Total
Expense1§
Expense2‖
ER visits
Inpatient stay
OBD visits
OP visits 
4,847 (54)
3,767 (45)
4,284 (49)
194 (4)
1,301 (28)
1,194 (15)
450 (13) 
11,291 (218)
9,318 (188)
10,242 (202)
311 (10)
3,110 (111)
2,256 (52)
820 (41) 
4,189 (51)
3,201 (41)
3,676 (46)
183 (4)
1,116 (27)
1,086 (15)
412 (13) 
3,197 (42)
2,407 (35)
2,782 (39)
141 (4)
726 (19)
852 (12)
315 (13) 
7,300 (228)
6,076 (212)
6,699 (224)
217 (14)
1,454 (97)
1,547 (62)
608 (64) 
2,915 (42)
2,156 (34)
2,514 (38)
135 (4)
676 (19)
804 (12)
295 (13) 
*

Any private includes any coverage through a private insurer or Tricare but not combined with a non-Medicare public plan any time during the year; any public includes any coverage through non-Medicare public plans (e.g., Medicaid or State Children’s Health Insurance Program); Medicare includes coverage through Medicare only; and uninsured includes no coverage throughout the year.

BMI <20 kg/m2 = underweight, 20 to <25 kg/m2 = normal weight, 25 to <30 kg/m2 = overweight, 30 to <35 kg/m2 = obese, and ≥35 kg/m2 = severely obese.

Includes expenditures for all health services, including dental, other medical, home health, and so forth.

§

Includes expenditures for inpatient stays, ER visits, office-based physician visits, outpatient department physician visits, and prescription medicine. ‖Includes expenditures for inpatient stays, ER visits, prescription medicine, and all office-based and outpatient department visits. FPL, federal poverty level; OBD, all office-based providers; OP, all outpatient department providers.

Compared with people in the ANS sample, people in the ADS sample were younger, more educated, more likely to have any private coverage, and healthier, with higher income and relatively lower average expenditures of each type.

Across all seven expenditure measures in each sample, those with type 2 diabetes had average expenditures higher than those without diabetes for any given BMI level. Compared with the ANS sample, people in the ADS sample had lower average expenditures for a given BMI category, by diabetes status and expenditure measure (Supplementary Table S1). Among individuals without diabetes in the ANS sample, normal-weight people had the lowest unadjusted average expenditures, but did not significantly differ from underweight people in all expenditure measures or from overweight in four measures (total, ER, inpatient stays, and OBD) (Supplementary Table S2). On the contrary, among people with diabetes, the overweight category had the lowest average expenditures for three expenditure measures (total, expense1, and expense2), and the obese category had the lowest average expenditures for the remaining four measures (ER, inpatient stays, OBD, and OP). However, in each measure, average expenditures for the normal-weight group did not differ significantly from the lowest average figures.

Similar to the ANS, people with diabetes, in the ADS, had average expenditures higher than those without diabetes for a given BMI category and expenditure measure. Among individuals without diabetes in the ADS sample, the normal-weight group had average expenditures lower than the average expenditures of those in each higher-weight category across all seven measures (Supplementary Table S3). Average expenditures of the normal-weight group were significantly less than those of the obese and severely obese groups in each of the seven measures, and those of the overweight group only in the case of ER expenditures. However, among people with diabetes in the ADS sample, the BMI category with the lowest average weight varied across expenditure measures as follows: the overweight group had the lowest average total and expense2 expenditures; the normal-weight group had the lowest average expense1, inpatient, and OP expenditures; the obese group had the lowest average ER expenditures; and the underweight group had the lowest average OBD expenditures. In all measures, the category with the lowest expenditures did not have expenditures that were significantly different from those of the normal-weight group.

Table 2 presents adjusted average expenditures by diabetes status and BMI category for each expenditure measure within the ANS and ADS samples. Tables 3 and 4 present differences in the adjusted average expenditures of the ANS and ADS samples, respectively. Similar to the unadjusted expenditures, for any given BMI category, average adjusted expenditures among people with diabetes was higher than those of people without diabetes in each model of the two samples (Tables 3 and 4). In the ANS sample (Table 3), among people in normal- and higher-weight groups, the overweight group had the lowest average expenditures in three measures (total, expense1, and expense2), and the obese group had the lowest average expenditures in the remaining four measures (ER visits, inpatient stays, OBD visits, and OP visits). However, among people without diabetes, the normal-weight group had the lowest expenditures across all measures. Compared with average expenditures of normal-weight people, the average expenditures of overweight people were lower in each of three measures (total, by $306, P <0.389; expense1, by $136, P <0.658; and expense2, by $158, P <0.645) and were higher among people without diabetes (total, by $17, P <0.890; expense1, by $74, P <0.465; and expense2, by $111, P <0.0.310) (Table 3). However, these differences were not statistically significant. The difference between people with and without diabetes in the difference in average expenditures for the overweight group versus the normal-weight group was not significant for any of the three measures (total, by $322, P <0.322; expense1, by $209, P <0.505; and expense2, by $269, P <0.433).

TABLE 2

Adjusted Expenditures per Person by Health Care Setting and BMI Category in People With and Without Diabetes

BMI Category*Average Expenditures per Person, $
TotalExpense1Expense2§ER VisitsInpatient StaysOBD VisitsOP Visits
Mean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)P
All respondents including smokers and those with cancer or CVD (ANS sample) 
 With diabetes Underweight 11,694 (1,891) 0.000 9,634 (1,758) 0.000 10,358 (1,764) 0.000 295 (58) 0.000 4,279 (820) 0.000 1,601 (306) 0.000 993 (466) 0.034 
Normal 7,599 (360) 0.000 6,182 (310) 0.000 6,960 (345) 0.000 307 (37) 0.000 1,849 (184) 0.000 1,684 (104) 0.000 923 (144) 0.000 
Overweight 7,293 (256) 0.000 6,046 (230) 0.000 6,802 (254) 0.000 266 (22) 0.000 1,747 (133) 0.000 1,737 (85) 0.000 791 (100) 0.000 
Obese 7,809 (332) 0.000 6,517 (341) 0.000 7,241 (335) 0.000 238 (20) 0.000 1,705 (123) 0.000 1,676 (74) 0.000 698 (66) 0.000 
Severely obese 8,599 (285) 0.000 7,221 (255) 0.000 8,042 (277) 0.000 250 (16) 0.000 1,712 (118) 0.000 1,937 (93) 0.000 947 (125) 0.000 
Without diabetes Underweight 4,652 (182) 0.000 3,407 (151) 0.000 3,885 (158) 0.000 203 (15) 0.000 1,303 (92) 0.000 1,109 (52) 0.000 390 (32) 0.000 
Normal 4,453 (95) 0.000 3,354 (80) 0.000 3,830 (85) 0.000 179 (6) 0.000 1,155 (49) 0.000 1,101 (22) 0.000 370 (20) 0.000 
Overweight 4,470 (88) 0.000 3,427 (74) 0.000 3,941 (82) 0.000 184 (6) 0.000 1,217 (50) 0.000 1,133 (22) 0.000 416 (17) 0.000 
Obese 4,642 (96) 0.000 3,589 (82) 0.000 4,140 (91) 0.000 200 (7) 0.000 1,228 (47) 0.000 1,209 (28) 0.000 458 (30) 0.000 
Severely obese 5,264 (139) 0.000 4,087 (113) 0.000 4,707 (126) 0.000 224 (9) 0.000 1,418 (68) 0.000 1,274 (35) 0.000 610 (45) 0.000 
Excluding smokers and those with cancer or CVD (ADS sample) 
 With diabetes Underweight 6,548 (1,882) 0.001 5,728 (1,948) 0.004 5,876 (1,904) 0.002 323 (106) 0.003 2,181 (1,154) 0.060 688 (118) 0.000 773 (484) 0.112 
Normal 5,120 (383) 0.000 4,171 (312) 0.000 4,663 (358) 0.000 295 (66) 0.000 848 (153) 0.000 1,163 (120) 0.000 514 (104) 0.000 
Overweight 5,235 (280) 0.000 4,350 (248) 0.000 4,846 (272) 0.000 239 (33) 0.000 1,040 (144) 0.000 1,190 (77) 0.000 588 (124) 0.000 
Obese 5,902 (387) 0.000 4,977 (399) 0.000 5,471 (385) 0.000 207 (32) 0.000 1,056 (136) 0.000 1,246 (91) 0.000 492 (70) 0.000 
Severely obese 6,688 (339) 0.000 5,614 (315) 0.000 6,202 (335) 0.000 228 (22) 0.000 1,158 (131) 0.000 1,467 (99) 0.000 833 (194) 0.000 
Without diabetes Underweight 2,991 (151) 0.000 2,120 (135) 0.000 2,441 (140) 0.000 137 (15) 0.000 690 (88) 0.000 755 (41) 0.000 255 (29) 0.000 
Normal 2,944 (80) 0.000 2,148 (70) 0.000 2,493 (76) 0.000 119 (5) 0.000 634 (33) 0.000 791 (16) 0.000 263 (18) 0.000 
Overweight 2,926 (62) 0.000 2,170 (51) 0.000 2,537 (58) 0.000 135 (6) 0.000 689 (33) 0.000 814 (19) 0.000 304 (18) 0.000 
Obese 2,976 (67) 0.000 2,224 (57) 0.000 2,613 (64) 0.000 150 (8) 0.000 710 (39) 0.000 858 (23) 0.000 303 (18) 0.000 
Severely obese 3,456 (104) 0.000 2,653 (91) 0.000 3,066 (99) 0.000 170 (9) 0.000 852 (57) 0.000 911 (30) 0.000 415 (36) 0.000 
BMI Category*Average Expenditures per Person, $
TotalExpense1Expense2§ER VisitsInpatient StaysOBD VisitsOP Visits
Mean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)P
All respondents including smokers and those with cancer or CVD (ANS sample) 
 With diabetes Underweight 11,694 (1,891) 0.000 9,634 (1,758) 0.000 10,358 (1,764) 0.000 295 (58) 0.000 4,279 (820) 0.000 1,601 (306) 0.000 993 (466) 0.034 
Normal 7,599 (360) 0.000 6,182 (310) 0.000 6,960 (345) 0.000 307 (37) 0.000 1,849 (184) 0.000 1,684 (104) 0.000 923 (144) 0.000 
Overweight 7,293 (256) 0.000 6,046 (230) 0.000 6,802 (254) 0.000 266 (22) 0.000 1,747 (133) 0.000 1,737 (85) 0.000 791 (100) 0.000 
Obese 7,809 (332) 0.000 6,517 (341) 0.000 7,241 (335) 0.000 238 (20) 0.000 1,705 (123) 0.000 1,676 (74) 0.000 698 (66) 0.000 
Severely obese 8,599 (285) 0.000 7,221 (255) 0.000 8,042 (277) 0.000 250 (16) 0.000 1,712 (118) 0.000 1,937 (93) 0.000 947 (125) 0.000 
Without diabetes Underweight 4,652 (182) 0.000 3,407 (151) 0.000 3,885 (158) 0.000 203 (15) 0.000 1,303 (92) 0.000 1,109 (52) 0.000 390 (32) 0.000 
Normal 4,453 (95) 0.000 3,354 (80) 0.000 3,830 (85) 0.000 179 (6) 0.000 1,155 (49) 0.000 1,101 (22) 0.000 370 (20) 0.000 
Overweight 4,470 (88) 0.000 3,427 (74) 0.000 3,941 (82) 0.000 184 (6) 0.000 1,217 (50) 0.000 1,133 (22) 0.000 416 (17) 0.000 
Obese 4,642 (96) 0.000 3,589 (82) 0.000 4,140 (91) 0.000 200 (7) 0.000 1,228 (47) 0.000 1,209 (28) 0.000 458 (30) 0.000 
Severely obese 5,264 (139) 0.000 4,087 (113) 0.000 4,707 (126) 0.000 224 (9) 0.000 1,418 (68) 0.000 1,274 (35) 0.000 610 (45) 0.000 
Excluding smokers and those with cancer or CVD (ADS sample) 
 With diabetes Underweight 6,548 (1,882) 0.001 5,728 (1,948) 0.004 5,876 (1,904) 0.002 323 (106) 0.003 2,181 (1,154) 0.060 688 (118) 0.000 773 (484) 0.112 
Normal 5,120 (383) 0.000 4,171 (312) 0.000 4,663 (358) 0.000 295 (66) 0.000 848 (153) 0.000 1,163 (120) 0.000 514 (104) 0.000 
Overweight 5,235 (280) 0.000 4,350 (248) 0.000 4,846 (272) 0.000 239 (33) 0.000 1,040 (144) 0.000 1,190 (77) 0.000 588 (124) 0.000 
Obese 5,902 (387) 0.000 4,977 (399) 0.000 5,471 (385) 0.000 207 (32) 0.000 1,056 (136) 0.000 1,246 (91) 0.000 492 (70) 0.000 
Severely obese 6,688 (339) 0.000 5,614 (315) 0.000 6,202 (335) 0.000 228 (22) 0.000 1,158 (131) 0.000 1,467 (99) 0.000 833 (194) 0.000 
Without diabetes Underweight 2,991 (151) 0.000 2,120 (135) 0.000 2,441 (140) 0.000 137 (15) 0.000 690 (88) 0.000 755 (41) 0.000 255 (29) 0.000 
Normal 2,944 (80) 0.000 2,148 (70) 0.000 2,493 (76) 0.000 119 (5) 0.000 634 (33) 0.000 791 (16) 0.000 263 (18) 0.000 
Overweight 2,926 (62) 0.000 2,170 (51) 0.000 2,537 (58) 0.000 135 (6) 0.000 689 (33) 0.000 814 (19) 0.000 304 (18) 0.000 
Obese 2,976 (67) 0.000 2,224 (57) 0.000 2,613 (64) 0.000 150 (8) 0.000 710 (39) 0.000 858 (23) 0.000 303 (18) 0.000 
Severely obese 3,456 (104) 0.000 2,653 (91) 0.000 3,066 (99) 0.000 170 (9) 0.000 852 (57) 0.000 911 (30) 0.000 415 (36) 0.000 
*

BMI <20 kg/m2 = underweight, 20 to <25 kg/m2 = normal weight, 25 to <30 kg/m2 = overweight, 30 to <35 kg/m2 = obese, and ≥35 kg/m2 = severely obese.

Includes expenditures for all health services including dental, other medical, home health, and so forth.

Includes expenditures for inpatient stays, ER visits, office-based physician visits, outpatient department physician visits, and prescription medicine.

§

Includes expenditures for inpatient stays, ER visits, prescription medicine, and all office-based and outpatient department visits.

TABLE 3

Differences in Adjusted Expenditures per Person in the Analytical Sample (ANS)

BMI Category*Differences in Average Expenditures per Person, $
TotalExpense1Expense2§ER VisitsInpatient StaysOBD VisitsOP Visits
Mean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)P
Between respective BMI category and normal-weight group 
 With diabetes Underweight 4,095 (1,826) 0.026 3,452 (1,681) 0.041 3,398 (1,690) 0.046 −11 (62) 0.856 2,430 (813) 0.003 −83 (307) 0.787 70 (463) 0.879 
Overweight −306 (354) 0.389 −136 (307) 0.658 −158 (341) 0.645 −41 (37) 0.273 −103 (201) 0.611 53 (109) 0.632 −132 (128) 0.305 
Obese 210 (433) 0.629 335 (398) 0.402 281 (421) 0.505 −69 (39) 0.081 −145 (183) 0.429 −8 (104) 0.942 −225 (119) 0.061 
Severely obese 1,000 (448) 0.027 1,039 (377) 0.006 1,082 (415) 0.010 −56 (37) 0.132 −137 (217) 0.527 253 (130) 0.053 24 (144) 0.870 
Without diabetes Underweight 199 (198) 0.316 53 (168) 0.752 55 (177) 0.757 24 (15) 0.112 148 (95) 0.120 8 (51) 0.872 20 (38) 0.593 
Overweight 17 (120) 0.890 74 (101) 0.465 111 (107) 0.301 5 (8) 0.557 62 (63) 0.330 32 (24) 0.188 46 (23) 0.051 
Obese 189 (129) 0.144 236 (111) 0.035 309 (121) 0.011 21 (9) 0.029 73 (67) 0.274 108 (30) 0.000 88 (34) 0.010 
Severely obese 811 (151) 0.000 733 (139) 0.000 876 (147) 0.000 45 (10) 0.000 262 (87) 0.003 173 (38) 0.000 240 (45) 0.000 
Between people with and without diabetes 
 Underweight 7,043 (1,903) 0.000 6,227 (1,768) 0.001 6,473 (1,778) 0.000 92 (60) 0.124 2,976 (829) 0.000 492 (318) 0.123 603 (467) 0.198 
Normal 3,146 (371) 0.000 2,828 (327) 0.000 3,130 (360) 0.000 127 (39) 0.001 694 (200) 0.001 583 (105) 0.000 553 (143) 0.000 
Overweight 2,824 (256) 0.000 2,619 (232) 0.000 2,861 (255) 0.000 82 (22) 0.000 530 (132) 0.000 604 (86) 0.000 375 (100) 0.000 
Obese 3,167 (337) 0.000 2,927 (350) 0.000 3,101 (341) 0.000 38 (21) 0.072 476 (129) 0.000 467 (78) 0.000 241 (70) 0.001 
Severely obese 3,335 (329) 0.000 3,135 (292) 0.000 3,336 (318) 0.000 27 (18) 0.135 294 (135) 0.030 663 (99) 0.000 336 (133) 0.012 
Between people with and without diabetes, less normal‖ 
 Underweight 3,897 (1,842) 0.036 3,398 (1,693) 0.046 3,343 (1,705) 0.051 −35 (64) 0.578 2,282 (823) 0.006 −91 (315) 0.773 50 (461) 0.914 
Overweight −322 (352) 0.362 −209 (314) 0.505 −269 (342) 0.433 −45 (39) 0.242 −165 (209) 0.433 21 (109) 0.848 −178 (128) 0.165 
Obese 21 (443) 0.963 99 (415) 0.812 −28 (435) 0.948 −89 (39) 0.024 −218 (199) 0.275 −116 (107) 0.281 −312 (123) 0.012 
Severely obese 189 (490) 0.700 306 (427) 0.474 206 (463) 0.657 −101 (38) 0.009 −400 (248) 0.108 80 (138) 0.562 −217 (152) 0.156 
BMI Category*Differences in Average Expenditures per Person, $
TotalExpense1Expense2§ER VisitsInpatient StaysOBD VisitsOP Visits
Mean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)P
Between respective BMI category and normal-weight group 
 With diabetes Underweight 4,095 (1,826) 0.026 3,452 (1,681) 0.041 3,398 (1,690) 0.046 −11 (62) 0.856 2,430 (813) 0.003 −83 (307) 0.787 70 (463) 0.879 
Overweight −306 (354) 0.389 −136 (307) 0.658 −158 (341) 0.645 −41 (37) 0.273 −103 (201) 0.611 53 (109) 0.632 −132 (128) 0.305 
Obese 210 (433) 0.629 335 (398) 0.402 281 (421) 0.505 −69 (39) 0.081 −145 (183) 0.429 −8 (104) 0.942 −225 (119) 0.061 
Severely obese 1,000 (448) 0.027 1,039 (377) 0.006 1,082 (415) 0.010 −56 (37) 0.132 −137 (217) 0.527 253 (130) 0.053 24 (144) 0.870 
Without diabetes Underweight 199 (198) 0.316 53 (168) 0.752 55 (177) 0.757 24 (15) 0.112 148 (95) 0.120 8 (51) 0.872 20 (38) 0.593 
Overweight 17 (120) 0.890 74 (101) 0.465 111 (107) 0.301 5 (8) 0.557 62 (63) 0.330 32 (24) 0.188 46 (23) 0.051 
Obese 189 (129) 0.144 236 (111) 0.035 309 (121) 0.011 21 (9) 0.029 73 (67) 0.274 108 (30) 0.000 88 (34) 0.010 
Severely obese 811 (151) 0.000 733 (139) 0.000 876 (147) 0.000 45 (10) 0.000 262 (87) 0.003 173 (38) 0.000 240 (45) 0.000 
Between people with and without diabetes 
 Underweight 7,043 (1,903) 0.000 6,227 (1,768) 0.001 6,473 (1,778) 0.000 92 (60) 0.124 2,976 (829) 0.000 492 (318) 0.123 603 (467) 0.198 
Normal 3,146 (371) 0.000 2,828 (327) 0.000 3,130 (360) 0.000 127 (39) 0.001 694 (200) 0.001 583 (105) 0.000 553 (143) 0.000 
Overweight 2,824 (256) 0.000 2,619 (232) 0.000 2,861 (255) 0.000 82 (22) 0.000 530 (132) 0.000 604 (86) 0.000 375 (100) 0.000 
Obese 3,167 (337) 0.000 2,927 (350) 0.000 3,101 (341) 0.000 38 (21) 0.072 476 (129) 0.000 467 (78) 0.000 241 (70) 0.001 
Severely obese 3,335 (329) 0.000 3,135 (292) 0.000 3,336 (318) 0.000 27 (18) 0.135 294 (135) 0.030 663 (99) 0.000 336 (133) 0.012 
Between people with and without diabetes, less normal‖ 
 Underweight 3,897 (1,842) 0.036 3,398 (1,693) 0.046 3,343 (1,705) 0.051 −35 (64) 0.578 2,282 (823) 0.006 −91 (315) 0.773 50 (461) 0.914 
Overweight −322 (352) 0.362 −209 (314) 0.505 −269 (342) 0.433 −45 (39) 0.242 −165 (209) 0.433 21 (109) 0.848 −178 (128) 0.165 
Obese 21 (443) 0.963 99 (415) 0.812 −28 (435) 0.948 −89 (39) 0.024 −218 (199) 0.275 −116 (107) 0.281 −312 (123) 0.012 
Severely obese 189 (490) 0.700 306 (427) 0.474 206 (463) 0.657 −101 (38) 0.009 −400 (248) 0.108 80 (138) 0.562 −217 (152) 0.156 
*

BMI <20 kg/m2 = underweight, 20 to <25 kg/m2 = normal weight, 25 to <30 kg/m2 = overweight, 30 to <35 kg/m2 = obese, and ≥35 kg/m2 = severely obese.

Includes expenditures for all health services, including dental, other medical, home health, and so forth.

Includes expenditures for inpatient stays, ER visits, office-based physician visits, outpatient department physician visits, and prescription medicine.

§

Includes expenditures for inpatient stays, ER visits, prescription medicine, and all office-based and outpatient department visits. ‖Estimate of people in respective BMI category minus estimate for people in normal-weight group.

TABLE 4

Differences in Adjusted Expenditures per Person in the Sample Excluding Smokers and Those With Cancer or CVD (ADS)

BMI Category*Differences in Average Expenditures per Person, $
TotalExpense1Expense2§ER VisitsInpatient StaysOBD VisitsOP Visits
Mean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)P
Between respective BMI category and normal-weight group 
 With diabetes Underweight 1,428 (1,835) 0.437 1,557 (1,908) 0.415 1,213 (1,854) 0.514 28 (119) 0.814 1,333 (1,119) 0.235 −475 (144) 0.001 259 (488) 0.596 
Overweight 115 (365) 0.754 179 (306) 0.561 183 (340) 0.591 −56 (68) 0.413 193 (185) 0.298 27 (116) 0.817 73 (130) 0.574 
Obese 782 (511) 0.127 806 (487) 0.100 808 (497) 0.106 −88 (66) 0.188 208 (193) 0.282 82 (121) 0.496 −22 (97) 0.821 
Severely obese 1,568 (468) 0.001 1,443 (398) 0.000 1,539 (449) 0.001 −67 (68) 0.330 310 (200) 0.123 303 (149) 0.043 319 (185) 0.086 
Without diabetes Underweight 47 (170) 0.783 −28 (155) 0.855 −52 (163) 0.751 19 (16) 0.236 55 (91) 0.545 −36 (42) 0.394 −8 (34) 0.819 
Overweight −19 (98) 0.849 22 (85) 0.798 44 (92) 0.635 16 (7) 0.032 55 (43) 0.199 24 (21) 0.274 41 (23) 0.084 
Obese 32 (98) 0.743 75 (87) 0.386 119 (93) 0.202 31 (9) 0.001 76 (49) 0.124 68 (25) 0.007 41 (19) 0.037 
Severely obese 512 (123) 0.000 505 (112) 0.000 573 (119) 0.000 51 (10) 0.000 218 (68) 0.001 120 (32) 0.000 152 (37) 0.000 
Between people with and without diabetes 
 Underweight 3,557 (1,881) 0.060 3,608 (1,948) 0.065 3,435 (1,905) 0.073 186 (107) 0.084 1,491 (1,157) 0.199 −66 (127) 0.602 519 (487) 0.288 
Normal 2,176 (400) 0.000 2,023 (327) 0.000 2,170 (374) 0.000 176 (66) 0.008 213 (154) 0.167 373 (121) 0.002 251 (105) 0.018 
Overweight 2,309 (287) 0.000 2,180 (259) 0.000 2,309 (279) 0.000 104 (34) 0.002 351 (149) 0.019 376 (79) 0.000 284 (122) 0.021 
Obese 2,926 (384) 0.000 2,753 (401) 0.000 2,858 (385) 0.000 57 (34) 0.091 345 (144) 0.017 387 (94) 0.000 189 (69) 0.007 
Severely obese 3,232 (363) 0.000 2,961 (335) 0.000 3,136 (358) 0.000 59 (22) 0.009 306 (136) 0.025 556 (102) 0.000 418 (196) 0.034 
Between people with and without diabetes, less normal‖ 
 Underweight 1,381 (1,834) 0.452 1,585 (1,910) 0.408 1,265 (1,855) 0.496 9 (120) 0.937 1,278 (1,121) 0.256 −439 (153) 0.004 267 (489) 0.585 
Overweight 133 (371) 0.720 157 (311) 0.614 139 (344) 0.686 −72 (69) 0.297 138 (186) 0.461 3 (115) 0.977 33 (131) 0.802 
Obese 750 (521) 0.152 730 (497) 0.143 689 (507) 0.176 −119 (67) 0.076 132 (200) 0.509 15 (120) 0.904 −63 (98) 0.523 
Severely obese 1,056 (503) 0.037 938 (425) 0.028 966 (482) 0.046 −118 (69) 0.090 92 (206) 0.655 183 (154) 0.238 167 (186) 0.370 
BMI Category*Differences in Average Expenditures per Person, $
TotalExpense1Expense2§ER VisitsInpatient StaysOBD VisitsOP Visits
Mean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)PMean (SE)P
Between respective BMI category and normal-weight group 
 With diabetes Underweight 1,428 (1,835) 0.437 1,557 (1,908) 0.415 1,213 (1,854) 0.514 28 (119) 0.814 1,333 (1,119) 0.235 −475 (144) 0.001 259 (488) 0.596 
Overweight 115 (365) 0.754 179 (306) 0.561 183 (340) 0.591 −56 (68) 0.413 193 (185) 0.298 27 (116) 0.817 73 (130) 0.574 
Obese 782 (511) 0.127 806 (487) 0.100 808 (497) 0.106 −88 (66) 0.188 208 (193) 0.282 82 (121) 0.496 −22 (97) 0.821 
Severely obese 1,568 (468) 0.001 1,443 (398) 0.000 1,539 (449) 0.001 −67 (68) 0.330 310 (200) 0.123 303 (149) 0.043 319 (185) 0.086 
Without diabetes Underweight 47 (170) 0.783 −28 (155) 0.855 −52 (163) 0.751 19 (16) 0.236 55 (91) 0.545 −36 (42) 0.394 −8 (34) 0.819 
Overweight −19 (98) 0.849 22 (85) 0.798 44 (92) 0.635 16 (7) 0.032 55 (43) 0.199 24 (21) 0.274 41 (23) 0.084 
Obese 32 (98) 0.743 75 (87) 0.386 119 (93) 0.202 31 (9) 0.001 76 (49) 0.124 68 (25) 0.007 41 (19) 0.037 
Severely obese 512 (123) 0.000 505 (112) 0.000 573 (119) 0.000 51 (10) 0.000 218 (68) 0.001 120 (32) 0.000 152 (37) 0.000 
Between people with and without diabetes 
 Underweight 3,557 (1,881) 0.060 3,608 (1,948) 0.065 3,435 (1,905) 0.073 186 (107) 0.084 1,491 (1,157) 0.199 −66 (127) 0.602 519 (487) 0.288 
Normal 2,176 (400) 0.000 2,023 (327) 0.000 2,170 (374) 0.000 176 (66) 0.008 213 (154) 0.167 373 (121) 0.002 251 (105) 0.018 
Overweight 2,309 (287) 0.000 2,180 (259) 0.000 2,309 (279) 0.000 104 (34) 0.002 351 (149) 0.019 376 (79) 0.000 284 (122) 0.021 
Obese 2,926 (384) 0.000 2,753 (401) 0.000 2,858 (385) 0.000 57 (34) 0.091 345 (144) 0.017 387 (94) 0.000 189 (69) 0.007 
Severely obese 3,232 (363) 0.000 2,961 (335) 0.000 3,136 (358) 0.000 59 (22) 0.009 306 (136) 0.025 556 (102) 0.000 418 (196) 0.034 
Between people with and without diabetes, less normal‖ 
 Underweight 1,381 (1,834) 0.452 1,585 (1,910) 0.408 1,265 (1,855) 0.496 9 (120) 0.937 1,278 (1,121) 0.256 −439 (153) 0.004 267 (489) 0.585 
Overweight 133 (371) 0.720 157 (311) 0.614 139 (344) 0.686 −72 (69) 0.297 138 (186) 0.461 3 (115) 0.977 33 (131) 0.802 
Obese 750 (521) 0.152 730 (497) 0.143 689 (507) 0.176 −119 (67) 0.076 132 (200) 0.509 15 (120) 0.904 −63 (98) 0.523 
Severely obese 1,056 (503) 0.037 938 (425) 0.028 966 (482) 0.046 −118 (69) 0.090 92 (206) 0.655 183 (154) 0.238 167 (186) 0.370 
*

BMI <20 kg/m2 = underweight, 20 to <25 kg/m2 = normal weight, 25 to <30 kg/m2 = overweight, 30 to <35 kg/m2 = obese, and ≥35 kg/m2 = severely obese.

Includes expenditures for all health services, including dental, other medical, home health, and so forth.

Includes expenditures for inpatient stays, ER visits, office-based physician visits, outpatient department physician visits, and prescription medicine.

§

Includes expenditures for inpatient stays, ER visits, prescription medicine, and all office-based and outpatient department visits. ‖Estimate of people in respective BMI category minus estimate for people in normal-weight group.

Compared with average of expenditures for inpatient stays and OBD visits for normal-weight people, the respective average for the obese group was lower among people with diabetes (inpatient stays, by $145, P <0.429, and OBD, by $8, P <0.942) but was higher among people without diabetes (inpatient stays, by $73, P <0.274, and OBD, by $108, P <0.001). The difference was significant only for OBD among people without diabetes. The difference between people with and without diabetes in the difference in average expenditures for inpatient stays and OBD between the obese and normal-weight groups was lower, but not statistically significant (inpatient stays, by $218, P <0.275, and OBD, by $116, P <0.281).

In the case of the ER visits, compared with people without diabetes, those with diabetes who were in either the obese or severely obese category had average expenditures significantly lower than those of the normal-weight group (obese vs. normal group by $89, P <0.024, and severely obese vs. normal group by $101, P <0.009). However, among people with diabetes, average expenditures for ER visits in each of the two categories—obese and severely obese—were lower than, but not statistically different from, those in the normal-weight category (obese vs. normal by $69, P <0.081, and severely obese vs. normal by $56, P <0.132). Among people without diabetes, average expenditures in each of the groups—obese and severely obese—were significantly higher than those in the normal-weight group (obese vs. normal by $21, P <0.029, and severely obese vs. normal by $45, P <0.001). The joint test of two-way interaction terms between BMI category and diabetes status was significant (P <0.044) (Supplementary Table S4).

For OP visits, the difference in average expenditures between the obese and normal-weight groups among people with diabetes was significantly lower than the difference among those without diabetes (by $312, P <0.012). Among people with diabetes, the obese group had average expenditures lower than in the normal-weight group, but the difference was not significant (by $225, P <0.061). In contrast, among people without diabetes, those in the obese category had average expenditures significantly higher than in the normal-weight group (by $88, P <0.01). The two-way interaction term between BMI category and diabetes status was not significant (P <0.116).

In the ADS sample, the difference in average expenditures between people with and without diabetes in the normal-weight category was higher than in the obese category in the OP model (by $63, P <0.5230) and was higher than in the overweight (by $72, P <0.297), obese (by $119, P <0.076), and severely obese (by $118, P <0.09) categories in the ER model (Table 4). However, these differences were not statistically significant. Even average expenditures among people with diabetes did not significantly differ between the normal- weight and obese categories in the OP model or between normal-weight people and those in each of the three higher-weight categories in the ER model. In all other models (total, expense1, expense2, inpatient stays, and OBD), normal-weight people had average expenditures lower than those of people in the higher-weight categories among people with diabetes. However, the difference in average expenditures among people with diabetes was statistically significant only between the normal-weight and severely obese groups and only in four measures—total, expense1, expense2, and OBD. The same trend was found in the difference in differences in expenditures. That is, the difference in average expenditures between people with and without diabetes in the normal-weight group were lower than those of each higher-weight group, and this difference in differences was statistically significant only between the normal-weight and severely obese groups and only in three measures (total, expense1, and expense2). In all models, wherever normal-weight people had higher average expenditures than those of any of the three higher-weight groups—overweight, obese, and severely obese—the differences were not statistically significant. The two-way interaction term between BMI category and diabetes status was statistically significant only in the OBD visits model (P <0.006).

Using nationally representative survey-based data, we analyzed total health care expenditures in addition to expenditures for four provider settings (OP, ERs, OBD, and inpatient stays), and two different summations of the four groups by individuals with and without type 2 diabetes. In the main ANS (excluding people with type 1 diabetes or GDM), people with diabetes had higher health care expenditures than those without diabetes across all BMI categories in each health care expenditure type we analyzed. Among people with diabetes, individuals with one or more BMI categories higher than normal weight had lower expenditures across seven measures (Supplementary Figure S1AG for the ANS and A1G1 for the ADS), but the difference in expenditures between the normal- weight group and the BMI group with the lowest expenditures was not statistically significant for any of the expenditure types. We did find evidence of a BMI/health care expenditure paradox in diabetes only in the case of expenditures for visits to OP and ERs. In contrast, we did not find any evidence of an obesity paradox in any of the seven expenditure types analyzed in the ADS sample (excluding current smokers and individuals with cancer or CVD from the main ANS). Our results suggest that common biases such residual confounding and reverse causation (e.g., when some diseases among people with diabetes cause low weight and high expenditures) are potential reasons for the presence of an obesity paradox in type 2 diabetes.

To our knowledge, only one prior study examined health care expenditures by BMI category among individuals with and without diabetes (27), and it found that normal-weight people with diabetes had total health care costs higher than those in the obese group. In addition, the normal-weight group had higher utilization of hospitals and ERs than the overweight group. However, the study included individuals with type 1 diabetes or GDM. In our study, we excluded individuals with type 1 diabetes or GDM from the ANS. In addition, we also designated as people with diabetes respondents who reported a diabetes diagnosis in the MEPS DCS, a self-administered paper-and-pencil questionnaire fielded at the end of the year to individuals who reported a diabetes diagnosis in the main MEPS household survey. The DCS correctly identifies who in the household has diabetes (sometimes a wrong household member has been previously reported as having or not having diabetes in the main survey). Those identified as not having diabetes in the DCS were already redesignated as not having diabetes in the public use data files, but the new household members now correctly identified with a diabetes diagnosis in the DCS are not flagged with diabetes in the public use data files. The earlier study did not incorporate this correction in diagnosis from the DCS. Furthermore, we included an interaction of age and diabetes status to account for differences in association between expenditures and diabetes status as people age and to account for the changes in expenditures with the duration of diabetes (i.e., with longer duration of diabetes, diabetes-related complications are expected to increase, thus resulting in higher health care expenditures, and older people, in general, are expected to have had a longer duration of diabetes). Although the previous study restricted analysis of expenditures to total health care expenditures, we not only analyzed total expenditures, but also expenditures specifically for hospital stays, OP visits, ER visits, and OBD visits, and two-variant summations of four settings. In our ADS sample, we also excluded smokers and people with cancer or CVD. The previous study did conduct sensitivity analyses on the sample (excluding smokers and people with cancer), but it did not exclude people with CVD, type 1 diabetes, or GDM.

Our study has some limitations. First, it used self-reported information, which may have been subject to reporting bias. For example, some respondents reported a diabetes diagnosis in the DCS but not in the main MEPS. However, the accuracy of self-reported diabetes status has been shown to be reasonably high (28). This study is cross-sectional; therefore, its findings cannot be interpreted as causal.

Acknowledgment

The views expressed in this article are those of the authors, and no official endorsement by the U.S. Department of Health and Human Services, the Agency for Healthcare Research and Quality, or Westat is intended or should be inferred.

Duality of Interest

No potential conflicts of interest relevant to this article were reported.

Author Contributions

V.K. researched data and wrote the introduction, Research Design and Methods, and Results sections. W.E. wrote the discussion section and reviewed and editing the manuscript. Both authors are guarantors of this work and, as such, had full access to all the data and take responsibility for the integrity of the data and the accuracy of the data analyses.

This article contains supplementary material online at https://doi.org/10.2337/figshare.17200961.

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