Longitudinal Associations Between Body Mass Index During Young Adulthood, Subsequent Weight Change, and Incident Diabetes During Mid- and Older-Adulthood in Non-Hispanic White and African American Populations: the Atherosclerosis Risk in Communities Study.

Background: Excess body mass index (BMI) and weight gain are well-known risk factors for diabetes. Nevertheless, the associations of BMI and weight gain in young adulthood with subsequent diabetes in African Americans, and the standardized effects of these weight variables have not been well studied. Methods: We studied 12,672 white and African American men and women 45-64 years of age (i.e., during mid-adulthood) who participated in the Atherosclerosis Risk in Communities Study visit 1 (1987-1989), and were reexamined at three follow-up examinations. Associations between recalled BMI at age 25 (i.e., during young adulthood) and subsequent weight change with incident diabetes at ages 45 and above (i.e., during mid-adulthood to older adulthood) were examined using Cox proportional hazard models. Results: Over the 9-year follow-up, we identified 1,501 cases of incident diabetes. The incidence rates were higher among African Americans (men: 24.5 and women: 26.3 per 1,000 person-years) compared to whites (men: 16.3 and women: 10.5 per 1,000 person years). Compared to normal-weight individuals at age 25, those who were overweight or obese and those who gained more weight after age 25 had a higher risk of developing diabetes later in all four race-sex groups with the highest risk in African Americans. In the race-sex groups combined, the mutually adjusted hazard ratio for BMI at age 25 and percent weight change were 1.97 (1.79-2.17) and 2.89 (2.59-3.11), respectively, comparing the 85th to the 15th percentiles of the exposures. Conclusions: African Americans were at higher risk of diabetes than whites. Both higher BMI at age 25 and subsequent weight gain were independently associated with higher risk for diabetes in all the race-sex groups; however, overall weight gain was more potent than BMI.