Diabetes-related complications are responsible for the majority of morbidity and mortality in patients with diabetes (1). Economically and socially marginalized populations are at increased risk for developing diabetes and, subsequently, diabetes complications (2). Understanding of the prevalence of acute and chronic complications among economically and socially marginalized patients with diabetes, and the risk factors for developing these complications, can inform clinics and ultimately lead to improved equity in diabetes-related morbidity and mortality.

We conducted a retrospective cross-sectional study using electronic health records data from the Accelerating Data Value Across a National Community Health Center Network (ADVANCE) clinical research network (CRN) of community health centers (CHCs) for calendar year 2019 (3). Data were obtained for 64,739 nonpregnant patients from 276 CHCs. We included patients aged 19–64 years, diagnosed with diabetes during or before 2019, who had at least one ambulatory visit during 2019.

Acute diabetes-related complications (termed acute complications) were identified using ICD-9, Clinical Modification (ICD-9-CM), and ICD-10-CM codes according to the Wharam et al. (4) classification and could occur on or after the first diabetes diagnosis. Each qualifying acute complication was counted distinctly if the interval between each visit diagnosis was at least 10 days. Chronic diabetes-related complications (termed chronic complications) were identified using ICD-9-CM and ICD-10-CM codes compiled and classified by the American Diabetes Association (5). A qualifying chronic complication occurred if it was diagnosed after the diabetes diagnosis.

We used generalized estimating equation (GEE) regression models to estimate covariate-adjusted prevalence differences in acute and chronic complications, separately, accounting for clustering of patients within clinics. GEE models included an identity link and exchangeable working correlation structure to estimate prevalence differences between covariate categories (e.g., male vs. female). Clusters were defined with use of patients’ most frequented clinic for ambulatory visits in 2019. All statistical tests were performed with a two-sided type I error of 5%. Analyses were conducted with R (version 4.1.1). The study was approved by the Oregon Health & Science University Institutional Review Board (IRB no. 00011858).

The prevalence of acute and chronic complications in 2019 was 13.3% and 73.1%, respectively. Patients experienced an average of 1.75 acute complications (range 1–28, median 1, interquartile range 1–2) and 3.2 chronic complications (range 1–27, median 3, interquartile range 1–4). The most common acute complications were infections (54.4%), followed by abnormal blood glucose or related metabolic abnormalities (22.3%) and myocardial infarction or transient coronary artery ischemia (7.6%). The most common chronic complications were endocrine or metabolic complications (20.9%), followed by cardiovascular disease (19.7%), neurological symptoms (16.5%), and renal (14.0%) and ophthalmic (5.2%) complications.

Acute and chronic complications were more likely to be diagnosed among patients with Medicaid or Medicare coverage, those in Medicaid expansion states, those with diagnoses of mental health or physical comorbidities (excluding diabetes complications), patients with insulin prescriptions, patients with uncontrolled HbA1c (≥9%), those who were overweight or obese, and patients with higher number of clinic visits relative to their counterparts. (See Table 1.) Non-Hispanic White patients, female patients, and patients residing in rural areas were more likely to have an acute complication than their counterparts. Patients older than 45 years and those diagnosed with substance use disorder were more likely to have a chronic complication diagnosis than their counterparts.

Table 1

Prevalence of and factors associated with acute and chronic diabetes complications among 64,739 patients with diabetes receiving care in CHCs in 2019

Overall (n = 64,739 [100%])Acute diabetes complications (n = 8,618 [13.3%])Chronic diabetes complications (n = 47,332 [73.1%])
Sex    
 Female (ref.) 34,543 (53.4) 14.8 74.1 
 Male 30,196 (46.6) 11.6* 72.0 
Age at first encounter (years)    
 19–26 1,355 (2.1) 10.6 47.9* 
 27–44 14,037 (21.7) 11.8 65.2* 
 45–64 (ref.) 49,347 (76.2) 13.8 76.1 
Race and ethnicity    
 Hispanic 28,957 (44.7) 11.9* 72.0 
 Non-Hispanic White (ref.) 16,636 (25.7) 17.3 76.3 
 Non-Hispanic Black 12,664 (19.6) 11.8* 73.2 
 Non-Hispanic other 2,817 (4.4) 12.2* 72.8 
 Unknown 3,665 (5.7) 12.6* 67.4 
FPL in 2019    
 >138 FPL for most visits (ref.) 9,400 (14.5) 13.6 73.6 
 ≤138 FPL for at least half of visits 42,229 (65.2) 13.8 74.3 
 Unknown 13,110 (20.3) 11.6 69.1 
Insurance at last visit in 2019    
 Medicaid (ref.) 22,559 (34.8) 15.9 76.8 
 Medicare 7,193 (11.1) 19.1 82.2 
 Other public 2,952 (4.6) 11.0* 72.2* 
 Private 14,911 (23.0) 11.1* 70.9* 
 Uninsured 17,124 (26.5) 9.9* 66.6* 
Status of diabetes diagnosis    
 Newly diagnosed in 2019 (ref.) 12,414 (19.2) 9.8 31.7 
 Diagnosed prior to 2019 52,325 (80.8) 14.1 82.9* 
Comorbidities in 2019    
 Mental health comorbidity only 9,032 (14.0) 14.0 77.3* 
 Physical comorbidity only 12,174 (18.8) 18.0* 78.7* 
 Mental health and physical comorbidity 7,514 (11.6) 21.5* 84.3* 
 No comorbidity (ref.) 36,019 (55.6) 9.8 67.8 
Insulin treatment ever    
 Yes 22,086 (34.1) 18.2* 84.6* 
 No (ref.) 42,653 (65.9) 10.8 67.2 
BMI at first visit in 2019 (kg/m2   
 <25 (ref.) 6,029 (9.3) 14.7 72.5 
 Between 25 and 30 15,102 (23.3) 12.5* 74.5* 
 ≥30 39,057 (60.3) 14.1* 74.7* 
 Unknown 4,551 (7.0) 7.6 55.8 
Substance use disorder in 2019    
 Yes 6,966 (10.8) 17.9 82.9* 
 No (ref.) 57,773 (89.2) 12.8 71.9 
HbA1c level in 2019    
 Controlled for all visits (<9%) (ref.) 37,126 (57.3) 12.9 74.0 
 Uncontrolled for all visits (≥9%) 11,164 (17.2) 14.5* 76.2* 
 In and out of control 8,367 (12.9) 16.6 84.3* 
 Unknown 8,082 (12.5) 10.4* 53.4* 
Patient rural/urban location    
 Urban or suburban (ref.) 50,616 (78.2) 12.2 72.6 
 Rural 14,123 (21.8) 17.3* 75.0 
Number of ambulatory visits in 2019    
 1 (ref.) 12,040 (18.6) 5.1 52.8 
 2–3 21,226 (32.8) 8.4* 69.0* 
 4–5 14,754 (22.8) 13.9* 80.1* 
 ≥6 16,719 (25.8) 24.9* 86.9* 
 State Medicaid expansion status in 2019    
 Medicaid expansion 40,450 (62.5) 15.2* 76.0* 
 Nonexpansion (ref.) 24,289 (37.5) 10.2 68.3 
Overall (n = 64,739 [100%])Acute diabetes complications (n = 8,618 [13.3%])Chronic diabetes complications (n = 47,332 [73.1%])
Sex    
 Female (ref.) 34,543 (53.4) 14.8 74.1 
 Male 30,196 (46.6) 11.6* 72.0 
Age at first encounter (years)    
 19–26 1,355 (2.1) 10.6 47.9* 
 27–44 14,037 (21.7) 11.8 65.2* 
 45–64 (ref.) 49,347 (76.2) 13.8 76.1 
Race and ethnicity    
 Hispanic 28,957 (44.7) 11.9* 72.0 
 Non-Hispanic White (ref.) 16,636 (25.7) 17.3 76.3 
 Non-Hispanic Black 12,664 (19.6) 11.8* 73.2 
 Non-Hispanic other 2,817 (4.4) 12.2* 72.8 
 Unknown 3,665 (5.7) 12.6* 67.4 
FPL in 2019    
 >138 FPL for most visits (ref.) 9,400 (14.5) 13.6 73.6 
 ≤138 FPL for at least half of visits 42,229 (65.2) 13.8 74.3 
 Unknown 13,110 (20.3) 11.6 69.1 
Insurance at last visit in 2019    
 Medicaid (ref.) 22,559 (34.8) 15.9 76.8 
 Medicare 7,193 (11.1) 19.1 82.2 
 Other public 2,952 (4.6) 11.0* 72.2* 
 Private 14,911 (23.0) 11.1* 70.9* 
 Uninsured 17,124 (26.5) 9.9* 66.6* 
Status of diabetes diagnosis    
 Newly diagnosed in 2019 (ref.) 12,414 (19.2) 9.8 31.7 
 Diagnosed prior to 2019 52,325 (80.8) 14.1 82.9* 
Comorbidities in 2019    
 Mental health comorbidity only 9,032 (14.0) 14.0 77.3* 
 Physical comorbidity only 12,174 (18.8) 18.0* 78.7* 
 Mental health and physical comorbidity 7,514 (11.6) 21.5* 84.3* 
 No comorbidity (ref.) 36,019 (55.6) 9.8 67.8 
Insulin treatment ever    
 Yes 22,086 (34.1) 18.2* 84.6* 
 No (ref.) 42,653 (65.9) 10.8 67.2 
BMI at first visit in 2019 (kg/m2   
 <25 (ref.) 6,029 (9.3) 14.7 72.5 
 Between 25 and 30 15,102 (23.3) 12.5* 74.5* 
 ≥30 39,057 (60.3) 14.1* 74.7* 
 Unknown 4,551 (7.0) 7.6 55.8 
Substance use disorder in 2019    
 Yes 6,966 (10.8) 17.9 82.9* 
 No (ref.) 57,773 (89.2) 12.8 71.9 
HbA1c level in 2019    
 Controlled for all visits (<9%) (ref.) 37,126 (57.3) 12.9 74.0 
 Uncontrolled for all visits (≥9%) 11,164 (17.2) 14.5* 76.2* 
 In and out of control 8,367 (12.9) 16.6 84.3* 
 Unknown 8,082 (12.5) 10.4* 53.4* 
Patient rural/urban location    
 Urban or suburban (ref.) 50,616 (78.2) 12.2 72.6 
 Rural 14,123 (21.8) 17.3* 75.0 
Number of ambulatory visits in 2019    
 1 (ref.) 12,040 (18.6) 5.1 52.8 
 2–3 21,226 (32.8) 8.4* 69.0* 
 4–5 14,754 (22.8) 13.9* 80.1* 
 ≥6 16,719 (25.8) 24.9* 86.9* 
 State Medicaid expansion status in 2019    
 Medicaid expansion 40,450 (62.5) 15.2* 76.0* 
 Nonexpansion (ref.) 24,289 (37.5) 10.2 68.3 

Data are n (%) or % unless otherwise indicated. FPL, federal poverty level; ref., reference category.

*

P < 0.05 based on GEE regression model to estimate covariates-adjusted prevalence differences in acute and chronic diabetes complications accounting for the clustering of patients within clinics. Both GEE models included an identity link and exchangeable working correlation structure to estimate prevalence differences between covariate categories (e.g., male vs. female). Clusters were defined using patients’ most frequented clinic for ambulatory visits in 2019.

Comorbidities exclude those included as chronic diabetes complications. Physical comorbidities included AIDS/HIV, cancer, cerebral palsy, cerebrovascular, chronic obstructive pulmonary disease, congestive heart failure, cystic fibrosis, developmental delay, Down syndrome, hemiplegia/paraplegia, hemophilia, inflammatory bowel disease, metastatic tumor, liver disease, muscular dystrophy, myocardial infarction, transplant, peptic ulcer, rheumatic disease, sickle cell disease, Tay-Sachs, seizures, and warfarin received. Mental comorbidities included autism, bipolar disorder, dementia, depression, mental retardation, and schizophrenia.

Expansion states include AK, CA, HI, IN, MA, MD, MN, MT, NM, NV, OH, OR, RI, WA, and WI; nonexpansion states were FL, KS, MO, NC, and TX.

This analysis has the following limitations: the prevalence of acute and chronic complications may be underestimated due to the lack of inpatient hospital data. Some complications identified as acute may actually be chronic. Chronic complications were counted following diabetes diagnosis, which may result in undercounting of diabetes-related chronic complications diagnosed prior to or at the time of diabetes diagnosis. Our sample included CHCs from the ADVANCE network and may not represent all primary care clinics across all states. Finally, this study presents a 1-year snapshot of CHC patients with diabetes and does not reflect accumulation of disease burden or the changes in diabetes control and management over time and their impact on complications.

In summary, one in eight CHC patients with diabetes was diagnosed with an acute complication and approximately three-quarters had a diagnosis of a chronic complication in 2019. Those with acute or chronic complications had a greater number of ambulatory visits and were more likely to experience comorbid mental health or physical health conditions than patients with diabetes not experiencing complications. These findings highlight the significant burden of acute and chronic complications for CHC patients with diabetes. This study reinforces the need for increased and ongoing support for CHCs to improve accessibility and affordability of diabetes care management and help mitigate diabetes-related complications among socioeconomically marginalized populations.

Acknowledgments. The authors acknowledge the significant contributions to this study that were provided by collaborating investigators in the Natural Experiments for Translation in Diabetes 3.0 (NEXT-D3) study and OCHIN clinics. This work was conducted with the ADVANCE CRN. ADVANCE is a CRN in PCORnet, the National Patient-Centered Research Network. ADVANCE is led by OCHIN in partnership with Health Choice Network, Fenway Health, and Oregon Health & Science University. ADVANCE’s participation in PCORnet is funded through the Patient-Centered Outcomes Research Institute (PCORI), contract no, RI-OCHIN-01-MC.

Funding. Research reported in this publication was supported by Centers for Disease Control and Prevention (CDC) grant (U18DP006536).

The content is solely the responsibility of the authors and does not necessarily represent the official views of the CDC.

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

Author Contributions. I.C. and N.H. designed the study and drafted the first version of the manuscript. J.H. and S.V. performed the data processing and analyses. M.M. provided statistical expertise. I.C., S.V., M.M., A.E.L., J.G., M.L.-T., H.A., J.E.D., and N.H. provided critical feedback on the analyses. All authors critically revised the manuscript for important intellectual content and approved the final version of the manuscript. N.H. is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Prior Presentation. Parts of this study were presented in abstract form at the North American Primary Care Research Group (NAPCRG) Annual Meeting, Quebec City, Canada, 19–23 November 2022.

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