Overall and central obesity and risk of type 2 diabetes in US black women

Objective: Obesity has risen to epidemic proportions in the United States, leading to an emerging epidemic of type 2 diabetes. African-American women are disproportionately affected by both conditions. While an association of overall obesity with increasing risk of diabetes has been documented in black women, the effect of fat distribution, specifically abdominal obesity, has not been studied. We examined the association of BMI, abdominal obesity, and weight gain with risk of type 2 diabetes. Research Methods and Procedures: During eight years of follow-up of 49,766 women from the Black Women's Health Study, 2472 incident cases of diabetes occurred. Cox proportional hazard models were used to estimate incidence rate ratios (IRRs), with control for age, physical activity, family history of diabetes, cigarette smoking, years of education, and time period of data collection. Results: Sixty-one percent of participants had a BMI >= 25 kg/m(2) (WHO definition of overweight). Compared with a BMI of < 23 kg/M-2, the IRR for a BMI of > 45 kg/M-2 was 23 (95% confidence interval, 17.0 to 31.0). The IRR for the highest quintile of waist-to-hip ratio relative to the lowest was 2.3 (95% confidence interval, 2.0 to 2.7) after control for BMI. Furthermore, at every level of BMI, an increased risk was observed for high waist-to-hip ratio relative to low. Discussion: Central obesity, as well as overall obesity, is a strong risk factor for diabetes in African-American women. Efforts to reduce the prevalence of obesity in African-American women are of paramount importance.