OBJECTIVE - To assess the relationship between measures of central and overall obesity and risk of diabetes.
DESIGN - Nested case-control study.
SETTING - Shanghai, China.
PARTICIPANTS - A total of 57 130 women were screened for diabetes at enrollment for the Shanghai Women's Health Study (SWHS), a population-based cohort study of Chinese women aged 40-70 y. In this study, 345 women diagnosed with diabetes and 2760 age-matched controls (eight controls per case), randomly selected from women who tested negative for urine glucose, were included.
RESULTS - Risk of diabetes increased significantly with increasing levels of obesity, particularly with measures of central obesity. Compared to those in the lowest quartile, women in the highest quartile of body mass index (BMI) (>/=26.57) and waist to hip ratio (WHR) (>/=0.855) had a 2.57-fold (95% CI 1.75-3.77) and a 6.05-fold (95% CI 4.05-9.04) increased risk of diabetes, respectively. The risk of diabetes was elevated with increasing WHR at all levels of BMI, while the positive association between BMI and diabetes was observed primarily among women with a low WHR. However, test for multiplicative interaction was not statistically significant.
CONCLUSIONS - Our data indicated that central obesity is a stronger risk factor for diabetes than overall obesity, suggesting that WHR may be a better indicator of risk of diabetes than BMI among Chinese women.