Racial/Ethnic Disparities in the Prevalence of Diabetes and Prediabetes by BMI: Patient Outcomes Research To Advance Learning (PORTAL) Multisite Cohort of Adults in the U.S.

OBJECTIVE: To examine racial/ethnic disparities in the prevalence of diabetes and prediabetes by BMI category. RESEARCH DESIGN AND METHODS: In a consortium of three U.S. integrated health care systems, 4,906,238 individuals aged ≥20 years during 2012-2013 were included. Diabetes and prediabetes were ascertained by diagnosis and laboratory results; antihyperglycemic medications were also included for diabetes ascertainment. RESULTS: for trend < 0.001). Racial/ethnic minorities reached a given diabetes prevalence at lower BMIs than whites; Hawaiians/Pacific Islanders and Asians had a diabetes prevalence of 24.6% (95% CI 24.1-25.2%) in overweight and 26.5% (26.3-26.8%) in obese class 1, whereas whites had a prevalence of 23.7% (23.5-23.8%) in obese class 2. The age-standardized prediabetes prevalence estimates in overweight among Hispanics (35.6% 35.4-35.7%), Asians (38.1% 38.0-38.3%), and Hawaiians/Pacific Islanders (37.5% 36.9-38.2%) were similar to those in obese class 4 among whites (35.3% 34.5-36.0%), blacks (36.8% 35.5-38.2%), and American Indians/Alaskan Natives (34.2% 29.6-38.8%). In adjusted models, the strength of association between BMI and diabetes was highest among whites (relative risk comparing obese class 4 with normal weight 7.64 95% CI 7.50-7.79) and lowest among blacks (3.16 3.05-3.27). The association between BMI and prediabetes was less pronounced. CONCLUSIONS: Racial/ethnic minorities had a higher burden of diabetes and prediabetes at lower BMIs than whites, suggesting the role of factors other than obesity in racial/ethnic disparities in diabetes and prediabetes risk and highlighting the need for tailored screening and prevention strategies.