Association of obesity profiles with type 2 diabetes in Chinese adults: Findings from the China health and nutrition survey

To examine longitudinal associations of obesity profiles, continuous BMI, and waist circumference (WC) with the risk of type 2 diabetes in Chinese adults.Data were derived from three waves (2009, 2015, and 2018) of the China Health and Nutrition Survey, and 3,595 adults aged 18-65 years who participated in at least two waves of the survey and had completed data were analyzed. Obesity profiles included BMI- or WC-related single obesity and combined obesity. Combined obesity was categorized into six groups including Group 1 with normal BMI and WC, Group 2 with normal BMI but pre-abdominal obesity, Group 3 with normal BMI but abdominal obesity, Group 4 with abnormal BMI (overweight and general obesity) and normal WC, Group 5 with abnormal BMI and pre-abdominal obesity, and Group 6 with abnormal BMI and abdominal obesity. Three-level mixed-effects logistic regressions with random intercept stratified by gender and restricted cubic splines were performed to examine ORs and 95%CIs for the risk of type 2 diabetes.In men, compared with subjects of Group 1, those in Group 3 had higher risk, with an OR of 4.83 (95% CI: 1.99-11.74), followed by those in Group 6 (OR = 4.05, 95%CI: 2.32-7.08) and Group 5 (OR = 2.98, 95%CI: 1.51-5.87) after adjusting for all potential confounders. For women, the subject of Group 6 had highest risk (OR = 8.79, 95%CI: 4.04-19.12), followed by Group 3 (OR = 3.30, 95%CI: 1.23-8.86) and Group 5 (OR = 3.16, 95%CI: 1.21-8.26). No significant association between abnormal BMI and normal WC (Group 4) was observed in both genders. Type 2 diabetes risk increased steeply at BMI of 23.5 kg/m2 and 22.5 kg/m2 or higher, and WC of 82.0 cm and 83.0 cm or higher in Chinese adult men and women, respectively (p for overall <0.001).Chinese adults with pre-abdominal or abdominal obesity had a relative high risk of type 2 diabetes independent of BMI levels. Lower BMI (≤23.5 kg/m2 for men and ≤22.5 kg/m2 for women) and lower WC (82.0 cm for men and ≤83.0 cm for women) values than the current Chinese obesity cut-offs were found to predict the risk of type 2 diabetes. These findings urge to inform WC modification and optimization of early screening guidelines.