To quantify the prevalence of diabetes and barriers to care among U.S. migrant farmworkers (i.e., those who travel from their permanent residence for seasonal farmwork).
Age-adjusted prevalence of self-reported diabetes and barriers to care were calculated among adult U.S. farmworkers from 2008 to 2017 National Agricultural Workers Surveys.
Among 16,913 farmworkers, 30.7% reported one or more barriers to care, most often due to cost. Age-adjusted self-reported prevalence of diabetes was 13.51% (95% CI 10.0–17.1) among migrant farmworkers and 10.8% (95% CI 9.0–12.6) among nonmigrant farmworkers with access to health care. Migrant farmworkers without recent health care had 83% lower odds of reporting known diabetes (adjusted odds ratio 0.17; 95% CI 0.06–0.54) compared with nonmigrant farmworkers, likely because of poor health care access and/or a healthy worker effect.
Many migrant farmworkers face barriers to care, which may lead to significant underdiagnosis of diabetes in this vulnerable population.
Introduction
Agricultural workers face occupational exposures and barriers to reliable, high-quality health care, which may place them at higher risk of undiagnosed and poorly controlled chronic diseases (1–4). Migrant farmworkers travel from their permanent residence for seasonal farmwork. The Centers for Disease Control and Prevention consider migrant farmworkers to be at high risk of communicable and noncommunicable diseases, and the 2020 American Diabetes Association guideline recommends tailored treatment for migrant farmworkers because they “face unique barriers that place them at high risk for undiagnosed and poorly controlled diabetes” (5).
Prior studies of diabetes prevalence among U.S. farmworkers have been limited by convenience sampling and small sample sizes. Estimates range from 9.3% among farmworkers in California (laboratory confirmed) to 16.1% among those in Arizona (self-reported), with 39.9% of those cases in California being previously undiagnosed diabetes (6,7).
No population-based, nationwide studies have examined the prevalence of diabetes and barriers to health care access among U.S. farmworkers or their association with migrant status. The aims of this study are to 1) measure the prevalence of self-reported diabetes and barriers to care among nonmigrant and migrant U.S. farmworkers, 2) quantify the association of migrant status with self-reported diabetes, and 3) quantify the association between migrant status and barriers to health care access.
Research Design and Methods
The National Agricultural Workers Survey is a population-based, serial, random sample survey conducted by the U.S. Department of Labor in 47 states and 696 counties during federal fiscal years, most recently in 2018. The seven levels of sampling include farm labor area, farmworker, employer, cycle, zip code, county, and region. Surveys are conducted in person at the farmworker’s place of employment. Cumulative response rates were 66% at the employer level and 92% at the worker level, and analyses found little evidence of nonresponse bias (8).
The study sample was restricted to adults age ≥18 years during federal fiscal years 2008 to 2017. Data from survey year 2018 were excluded because questions about access and barriers to care were removed in the 2018 survey. Fewer than 3% of respondents had missing data. Demographic variables included migrant status, age, sex, region of farmwork, country of origin, primary language, English proficiency level, annual income, highest completed level of education, documentation status, and insurance status (more details provided in Supplementary Materials).
Statistical Analyses
Analyses were conducted using the National Agricultural Workers Survey complex survey procedures. We computed crude prevalence and 95% CIs within survey years 2008 to 2017 by age and sex. We calculated age-adjusted prevalence using corresponding U.S. Census data via direct standardization (9). We calculated prevalence odds ratios (pORs) through multivariable logistic regression and stratified models by recent health care access because of statistically significant interaction. Participants with missing data were excluded from analyses. We used Stata software (version 17.0; StataCorp). A two-sided P value <0.05 was deemed significant.
Results
Among 16,913 participants, the mean (SD) age was 40 (13) years, 79% (n = 13,316) were men, and 15% (n = 2,610) were migrant workers. In total, 397 individuals were excluded because of missing data (2% of respondents).
Migrant workers were younger and more likely to be male (Table 1). Most farmworkers were born in Mexico. More migrant workers lacked health insurance compared with nonmigrant workers, had a median annual income <$20,000, and had lower educational attainment. Significantly fewer migrants spoke English as their primary language or reported English proficiency.
Unweighted characteristics of U.S. migrant and nonmigrant farmworkers by age, sex, and sociodemographic factors from the National Agricultural Worker Survey, 2008–2017 (N = 16,913)
. | Migrant farmworkers (n = 2,610) . | Nonmigrant farmworkers (n = 14,303) . |
---|---|---|
Male sex | 2,208 (85) | 11,108 (78) |
Age-group, years | ||
18–39 | 1,454 (56) | 7,567 (35) |
40–59 | 949 (36) | 5,670 (40) |
>60 | 207 (8) | 1,066 (8) |
Highest level of education | ||
Below 9th grade | 1,587 (61) | 7,252 (51) |
9th–12th grade | 853 (33) | 5,776 (40) |
Any college | 170 (7) | 1,275 (9) |
Primary language | ||
English | 215 (8) | 3,111 (22) |
Spanish | 2,264 (87) | 10,909 (76) |
Other | 131 (5) | 283 (2) |
English proficiency | ||
None or somewhat | 2,254 (86) | 10,392 (73) |
Good | 356 (14) | 3,911 (27) |
Place of birth | ||
U.S. | 286 (11) | 3,257 (23) |
Puerto Rico | 89 (3) | 56 (0.4) |
Mexico | 2,077 (80) | 10,161 (71) |
Central or South America or Caribbean | 146 (6) | 761 (5) |
Other | 11 (0.5) | 69 (0.4) |
Median annual income <$20,000 | 1,840 (71) | 6,572 (46) |
Insured | 548 (21) | 5,531 (38) |
Undocumented status | 1,360 (52) | 7,092 (50) |
Region in U.S | ||
East | 531 (20) | 1,603 (11) |
Southeast | 339 (13) | 2,002 (14) |
Midwest | 341 (13) | 1,493 (10) |
Southwest | 171 (7) | 1,138 (8) |
Northwest | 427 (16) | 2,189 (15) |
California | 801 (31) | 5,878 (41) |
. | Migrant farmworkers (n = 2,610) . | Nonmigrant farmworkers (n = 14,303) . |
---|---|---|
Male sex | 2,208 (85) | 11,108 (78) |
Age-group, years | ||
18–39 | 1,454 (56) | 7,567 (35) |
40–59 | 949 (36) | 5,670 (40) |
>60 | 207 (8) | 1,066 (8) |
Highest level of education | ||
Below 9th grade | 1,587 (61) | 7,252 (51) |
9th–12th grade | 853 (33) | 5,776 (40) |
Any college | 170 (7) | 1,275 (9) |
Primary language | ||
English | 215 (8) | 3,111 (22) |
Spanish | 2,264 (87) | 10,909 (76) |
Other | 131 (5) | 283 (2) |
English proficiency | ||
None or somewhat | 2,254 (86) | 10,392 (73) |
Good | 356 (14) | 3,911 (27) |
Place of birth | ||
U.S. | 286 (11) | 3,257 (23) |
Puerto Rico | 89 (3) | 56 (0.4) |
Mexico | 2,077 (80) | 10,161 (71) |
Central or South America or Caribbean | 146 (6) | 761 (5) |
Other | 11 (0.5) | 69 (0.4) |
Median annual income <$20,000 | 1,840 (71) | 6,572 (46) |
Insured | 548 (21) | 5,531 (38) |
Undocumented status | 1,360 (52) | 7,092 (50) |
Region in U.S | ||
East | 531 (20) | 1,603 (11) |
Southeast | 339 (13) | 2,002 (14) |
Midwest | 341 (13) | 1,493 (10) |
Southwest | 171 (7) | 1,138 (8) |
Northwest | 427 (16) | 2,189 (15) |
California | 801 (31) | 5,878 (41) |
Data presented as n (%).
Given diabetes was self-reported and likely underdiagnosed, prevalence was calculated among farmworkers who accessed health care in the last 2 years (Table 2). Among those with access, the unadjusted prevalence of self-reported diabetes was 9.9% (95% CI 7.26–13.35) among migrant workers and 8.7% (95% CI 7.49–10.00) among nonmigrant workers. The age-adjusted prevalence of diabetes was 13.5% (95% CI 9.97–17.05) among migrant workers and 10.8% (95% CI 8.96–12.55) among nonmigrant workers.
Multivariable logistic regression models of association of migrant status with diabetes stratified by access to care
Predictor . | Unadjusted . | Model 1: adjusteda . | Model 2: adjustedb . | |||
---|---|---|---|---|---|---|
Did not access care (n = 5,174) . | Accessed care (n = 9,579) . | Did not access care . | Accessed care . | Did not access care . | Accessed care . | |
Migrant status | ||||||
Nonmigrant (ref.) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
Migrant | 0.18 (0.06–0.51) | 1.16 (0.80–1.68) | 0.21 (0.07–0.61) | 1.30 (0.89–1.88) | 0.17 (0.06–0.54) | 1.09 (0.76–1.56) |
Age, years | ||||||
18–39 (ref.) | 1.00 | 1.00 | 1.00 | 1.00 | ||
40–59 | 14.41 (4.12–50.35) | 5.03 (3.64–6.96) | 11.74 (3.39–40.69) | 3.79 (2.69–5.33) | ||
≥60 | 28.42 (6.53–123.70) | 7.07 (4.47–11.20) | 17.16 (3.57–82.44) | 4.88 (2.90–8.20) | ||
Sex | ||||||
Male (ref.) | 1.00 | 1.00 | 1.00 | 1.00 | ||
Female | 4.96 (2.14–11.47) | 1.18 (0.86–1.61) | 4.09 (1.73–9.66) | 1.18 (0.88–1.57) | ||
English proficiency | ||||||
None to low (ref.) | 1.00 | 1.00 | ||||
Some to good | 1.13 (0.14–9.27) | 0.67 (0.43–1.06) | ||||
Education level | ||||||
0–8 years | 1.00 | 1.00 | ||||
9–12 years | 0.32 (0.04–2.38) | 0.68 (0.49–0.93) | ||||
Beyond high school | 0.67 (0.10–4.57) | 0.52 (0.25–1.06) | ||||
Documentation status | ||||||
Documented (ref.) | 1.00 | 1.00 | ||||
Undocumented | 0.58 (0.20–1.68) | 0.56 (0.41–0.77) | ||||
Income category, $ | ||||||
<20,000 (ref.) | 1.00 | 1.00 | ||||
≥20,000 | 0.56 (0.26–1.22) | 0.89 (0.67–1.19) | ||||
Insurance status | ||||||
No insurance (ref.) | 1.00 | 1.00 | ||||
Insured | 0.84 (0.27–2.58) | 1.01 (0.99–1.03) |
Predictor . | Unadjusted . | Model 1: adjusteda . | Model 2: adjustedb . | |||
---|---|---|---|---|---|---|
Did not access care (n = 5,174) . | Accessed care (n = 9,579) . | Did not access care . | Accessed care . | Did not access care . | Accessed care . | |
Migrant status | ||||||
Nonmigrant (ref.) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
Migrant | 0.18 (0.06–0.51) | 1.16 (0.80–1.68) | 0.21 (0.07–0.61) | 1.30 (0.89–1.88) | 0.17 (0.06–0.54) | 1.09 (0.76–1.56) |
Age, years | ||||||
18–39 (ref.) | 1.00 | 1.00 | 1.00 | 1.00 | ||
40–59 | 14.41 (4.12–50.35) | 5.03 (3.64–6.96) | 11.74 (3.39–40.69) | 3.79 (2.69–5.33) | ||
≥60 | 28.42 (6.53–123.70) | 7.07 (4.47–11.20) | 17.16 (3.57–82.44) | 4.88 (2.90–8.20) | ||
Sex | ||||||
Male (ref.) | 1.00 | 1.00 | 1.00 | 1.00 | ||
Female | 4.96 (2.14–11.47) | 1.18 (0.86–1.61) | 4.09 (1.73–9.66) | 1.18 (0.88–1.57) | ||
English proficiency | ||||||
None to low (ref.) | 1.00 | 1.00 | ||||
Some to good | 1.13 (0.14–9.27) | 0.67 (0.43–1.06) | ||||
Education level | ||||||
0–8 years | 1.00 | 1.00 | ||||
9–12 years | 0.32 (0.04–2.38) | 0.68 (0.49–0.93) | ||||
Beyond high school | 0.67 (0.10–4.57) | 0.52 (0.25–1.06) | ||||
Documentation status | ||||||
Documented (ref.) | 1.00 | 1.00 | ||||
Undocumented | 0.58 (0.20–1.68) | 0.56 (0.41–0.77) | ||||
Income category, $ | ||||||
<20,000 (ref.) | 1.00 | 1.00 | ||||
≥20,000 | 0.56 (0.26–1.22) | 0.89 (0.67–1.19) | ||||
Insurance status | ||||||
No insurance (ref.) | 1.00 | 1.00 | ||||
Insured | 0.84 (0.27–2.58) | 1.01 (0.99–1.03) |
Data presented as OR (95% CI). Bolded values represent statistically significant results, P < 0.05.
Adjusted for age and sex.
Adjusted for age, sex, English proficiency, education level, documentation status, annual income, and insurance status. ref., reference.
Approximately one-third (30.7%) of farmworkers reported at least one barrier to health care access (Table 3), most often cost (27.9%). Compared with nonmigrant workers, migrant workers were more likely to report language barriers (pOR 1.92; 95% CI 1.51–2.42), transportation barriers (pOR 2.34; 95% CI 1.67–3.20), and not knowing where health services were available (pOR 3.39; 95% CI 2.30–4.95).
Population-based unadjusted and age-adjusted prevalence of self-reported diabetes among those with access to health care and barriers to health care among migrant and nonmigrant U.S. farmworkers, 2008–2017
. | Migrant farmworkers . | Nonmigrant farmworkers . | ||
---|---|---|---|---|
Unadjusteda . | Adjustedb . | Unadjusteda . | Adjustedb . | |
Self-reported diabetes | ||||
Overall | 9.90 (7.26–13.35) | 13.51 (9.97–17.05) | 8.66 (7.49–10.00) | 10.76 (8.96–12.55) |
Sex | ||||
Female | 9.55 (4.26–20.04) | 15.23 (5.95–24.51) | 9.21 (6.99–12.03) | 9.35 (6.94–11.76) |
Male | 10.03 (7.39–13.47) | 13.08 (9.72–16.43) | 8.35 (7.07–9.84) | 10.87 (8.74–12.99) |
Age, years | ||||
18–39 (ref.) | 3.76 (2.02–6.91) | 3.16 (2.33–4.28) | ||
40–59 | 17.10 (11.09–25.45) | 13.93 (11.79–16.39) | ||
≥60 | 23.39 (15.64–33.46) | 17.94 (12.40–25.23) | ||
Barriers to care | ||||
Overall | 31.46 (27.00–36.29) | 27.78 (24.01–31.55) | 29.74 (27.96–31.58) | 28.23 (26.17–30.29) |
Sex | ||||
Female | 28.39 (18.47–40.96) | 23.63 (15.15–32.10) | 32.19 (29.05–35.50) | 30.62 (24.74–35.49) |
Male | 32.28 (28.39–36.52) | 28.85 (25.23–32.47) | 28.68 (26.78–30.67) | 27.26 (25.13–29.39) |
Age, years | ||||
18–39 (ref.) | 32.42 (26.30–39.22) | 31.31 (29.00–33.73) | ||
40–59 | 33.10 (26.97–39.85) | 28.75 (26.50–31.12) | ||
≥60 | 13.26 (8.49–20.12) | 22.78 (17.57–28.98) |
. | Migrant farmworkers . | Nonmigrant farmworkers . | ||
---|---|---|---|---|
Unadjusteda . | Adjustedb . | Unadjusteda . | Adjustedb . | |
Self-reported diabetes | ||||
Overall | 9.90 (7.26–13.35) | 13.51 (9.97–17.05) | 8.66 (7.49–10.00) | 10.76 (8.96–12.55) |
Sex | ||||
Female | 9.55 (4.26–20.04) | 15.23 (5.95–24.51) | 9.21 (6.99–12.03) | 9.35 (6.94–11.76) |
Male | 10.03 (7.39–13.47) | 13.08 (9.72–16.43) | 8.35 (7.07–9.84) | 10.87 (8.74–12.99) |
Age, years | ||||
18–39 (ref.) | 3.76 (2.02–6.91) | 3.16 (2.33–4.28) | ||
40–59 | 17.10 (11.09–25.45) | 13.93 (11.79–16.39) | ||
≥60 | 23.39 (15.64–33.46) | 17.94 (12.40–25.23) | ||
Barriers to care | ||||
Overall | 31.46 (27.00–36.29) | 27.78 (24.01–31.55) | 29.74 (27.96–31.58) | 28.23 (26.17–30.29) |
Sex | ||||
Female | 28.39 (18.47–40.96) | 23.63 (15.15–32.10) | 32.19 (29.05–35.50) | 30.62 (24.74–35.49) |
Male | 32.28 (28.39–36.52) | 28.85 (25.23–32.47) | 28.68 (26.78–30.67) | 27.26 (25.13–29.39) |
Age, years | ||||
18–39 (ref.) | 32.42 (26.30–39.22) | 31.31 (29.00–33.73) | ||
40–59 | 33.10 (26.97–39.85) | 28.75 (26.50–31.12) | ||
≥60 | 13.26 (8.49–20.12) | 22.78 (17.57–28.98) |
Data presented as % (95% CI).
Calculated using National Agricultural Workers Survey weighting.
Adjusted to the 2007–2017 U.S. Census population using age-groups 20–39, 40–59, and ≥60 years.
Migrant farmworkers with poor health care access had 82% lower odds of reporting diabetes (OR 0.18; 95% CI 0.06–0.51) compared with nonmigrant workers. Among those with recent health care access, migrant workers had similar odds of diabetes compared with nonmigrant workers (OR 1.16; 95% CI 0.80–1.68). Results were similar after adjusting for age and sex (adjusted OR [aOR] 0.21; 95% CI 0.07–0.61) and after additionally adjusting for English proficiency, education level, documentation status, annual income, and insurance status. The adjusted odds of reporting diabetes increased with age (aOR 4.85 for age >60 years; 95% CI 2.71–8.68) and decreased with undocumented status (aOR 0.49; 95% CI 0.35–0.69).
All farmworkers were likely to report at least one barrier to health care in both the unadjusted (OR 1.08; 95% CI 0.87–1.36) and adjusted analyses (Supplementary Table 1). Migrant farmworkers with a high school or higher level of education were less likely to report barriers to health care. Undocumented migrant farmworkers had 180% higher odds of reporting barriers to care compared with undocumented nonmigrant workers (95% CI 1.58–2.22).
Conclusions
Our study highlights three salient findings. First, this is the first national estimate of diabetes among U.S migrant farmworkers (age adjusted 13.5%). Second, one-third of U.S. farmworkers reported at least one barrier to accessing health care, most often cost. Lastly, migrant farmworkers with poor health care access had significantly lower odds (82%) of reporting diabetes compared with nonmigrant farmworkers, but these differences resolved for migrants with access to care, suggesting many migrant farmworkers with poor health care access are unaware they have diabetes.
U.S. farmworkers were predominantly young, male, low income, Spanish speaking, and Latino. Migrant farmworkers were more likely to be foreign born, uninsured, and undocumented, with limited English proficiency and lower educational attainment compared with their nonmigrant counterparts. The high prevalence of barriers to care were unsurprising, given the high rates of extreme poverty and low rates of health insurance in our sample. Poverty, immigration status, limited English proficiency, poor access to care, and lack of health insurance have all been associated with an increased risk of diabetes, including undiagnosed diabetes (10–14). Overall, we expected migrant farmworkers to be at higher risk of diabetes, given their socioeconomic vulnerabilities.
Given diabetes was self-reported and likely underdiagnosed, we calculated national diabetes prevalence among farmworkers with health care access in the previous 2 years and found rates of 13.5% and 10.8% among migrant and nonmigrant workers, respectively. Compared with a national estimate of 11.3%, migrant farmworkers seem to be at higher risk of diabetes than the general U.S. population (15). However, we expected a higher prevalence, given 75% of the farmworkers in our sample were Latino, a U.S. population with an estimate of diabetes of 22.1% (16).
There are several possible reasons for the lower-than-expected prevalence of diabetes in our cohort. Given 23% of the U.S. population has undiagnosed diabetes, the true population prevalence of diabetes among U.S. farmworkers is almost certainly higher (17). Furthermore, farmworkers in our study had a high proportion of several socioeconomic factors, including being from Mexico having a low income and poor access to care, that increase estimated rates of undiagnosed diabetes to as high as 61% (18). Extrapolating these data, the true prevalence of diabetes among U.S. farmworkers may approach 35% among migrant and 28% among nonmigrant workers.
In a stratified regression analysis of those who with poor health care access, migrant farmworkers had significantly lower odds (82%) of self-reporting diabetes compared with nonmigrant farmworkers; however, the odds were similar among farmworkers with recent access to care. This further supports that poor health care access contributes to an underestimation of diabetes in this population, especially for migrant workers.
Another possible contributor to the lower prevalence of diabetes among U.S. farmworkers is the healthy immigrant paradox, which refers to better health outcomes seen in foreign-born, recently arrived individuals in the U.S. compared with the general population and native-born individuals of the same race or ethnicity (17,18). Migrant farmwork may select for fitter individuals who can both endure the grueling manual labor and travel across borders at regular intervals (i.e., a healthy worker effect) (19,20). Although these phenomena may partially explain our findings, our stratified analyses suggest access to care is a stronger contributor.
Limitations
Survey questions did not differentiate between prediabetes or type 1 or 2 diabetes, nor did they assess method or time of diagnosis or severity of disease. Data were self-reported and subject to recall bias, although there are ethical concerns with population-based laboratory diagnosis in vulnerable populations without linkage to care. Other limitations include the cross-sectional design and lack of 2018 data because of survey question changes, and the yearly random-sample survey design includes the possibility of repeat interviews, although the large sample size makes this unlikely to influence findings.
Conclusion
Many U.S. migrant farmworkers have diabetes, and a significant portion face barriers to health care access, which may be leading to a significant underdiagnosis of diabetes in this vulnerable population. Future studies aimed at large-scale, community-based point-of-care screening with linkage to care could better ascertain the true burden of diabetes and undiagnosed diabetes in this population.
This article contains supplementary material online at https://doi.org/10.2337/figshare.24112467.
R.M.O. and C.P.N. contributed equally to this work.
Article Information
Acknowledgments. The authors thank the community of Immokalee, FL, a migrant farmworker community from which the authors learned an immense amount about health and disease in this population.
Duality of Interest. No potential conflicts of interest relevant to this article were reported.
Author Contributions. R.M.O. and C.P.N. designed the study, researched data, and wrote the manuscript. N.L. and M.O. researched data and reviewed/edited the manuscript. D.P. reviewed/edited the manuscript. R.M.O. and C.P.N. are the guarantors of this work and, as such, had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.