Adiposity, Prediabetes and Diabetes in Foreign versus Native Blacks in the United States

Blacks in the United States (U.S.) face a disproportionately high burden of diabetes. The foreign‐born are a growing subgroup of blacks who have had unique environmental exposures. Possible heterogeneity in adiposity and dysglycemia (diabetes and prediabetes) between native and foreign blacks is understudied. This is in large part due to the paucity of datasets with biochemical assessment of disease, anthropometric measures and an adequate sample size of foreign‐born blacks. Pooling two national studies, we created a large dataset of U.S. blacks to examine differences in diabetes and prediabetes by nativity, and the contribution of adiposity in explaining these differences. Methods We concatenated data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort with five cycles of the National Health and Nutrition Examination Survey (NHANES) 2005–2014, restricting our analysis to those self‐identifying as black. Diabetes was defined as previous physician diagnosis, use of glucose lowering medication, fasting glucose ≥ 126 mg/dL or non‐fasting glucose ≥ 200 mg/dL. Prediabetes was defined as fasting glucose 100–125 mg/dL and non‐fasting glucose 140–199 mg/dL. We compared Body Mass Index (BMI), Waist Circumference (WC), crude prevalence of diabetes and prediabetes by nativity using t‐tests and chi‐squared tests. Using polytomous regressions, we estimated the prevalence ratio of nativity on dysglycemia while adjusting for age and adiposity (BMI and WC). All models additionally control for data source to account for unmeasured differences in study methods. Results Characteristics of native versus foreign blacks are presented in Table 1. Mean age and BMI were significantly lower in foreign black men and women than their native counterparts. Mean WC was significantly lower in foreign black men than native black men. Crude prevalence of diabetes and prediabetes was not significantly different by nativity. Associations of nativity with dysglycemia using native blacks as referent is presented in Figure 1. Adjusting for age and WC, the prevalence ratio of diabetes comparing foreign black women to native black women was statistically significant (PR= 1.22, 95% CI: 1.02, 1.45). Conclusions The crude prevalence of dysglycemia was similarly high in foreign‐born and native‐born blacks, even though foreign‐born blacks had significantly lower adiposity. This susceptibility in foreign blacks may be due to a heightened metabolic response to obesity or presence of other obesity‐unrelated risk factors. Further understanding of these factors can inform targeted prevention strategies. 1 Characteristics of Native versus Foreign Blacks in a Pooled Sample from REGARDS and NHANESMenNative Black (n=5411) Foreign Black (n=228) p‐valueAge (year) 61.90 (61.57, 62.22) 56.10 (54.13, 58.07) <0.01 BMI (kg/m 2 ) 29.14 (28.99, 29.29) 27.26 (26.69, 27.84) <0.01 Waist circumference (cm) 100.3 (99.87, 100.70) 95.27 (93.77, 96.77) <0.01 % Diabetes 32.45 (31.20, 33.70) 31.58 (25.55, 37.61) 0.78 % Prediabetes 18.28 (17.25, 19.31) 22.37 (16.96, 27.78) 0.12WomenNative Black (n=8191) Foreign Black (n=200) p‐valueAge (year) 62.02 (61.77, 62.28) 56.35 (54.38, 58.31) <0.01 BMI (kg/m 2 ) 32.01 (31.85, 32.17) 30.26 (29.43, 31.09) <0.01 Waist circumference (cm) 97.84 (97.50, 98.19) 96.31 (94.36, 98.26) 0.18 % Diabetes 29.80 (28.81, 30.79) 36.00 (29.35, 42.65) 0.06% Prediabetes 16.65 (15.85, 17.46) 21.50 (15.81, 27.19) 0.07