Epidemiology and risk factors for diabetes in the suburbs of Beijing: a retrospective cohort study

OBJECTIVE: We aimed to detect the incidence and risk factors of type 2 diabetes mellitus (T2DM) development in the suburbs of Beijing. DESIGN: Cohort study with record linkage to incidence data. SETTING: We performed a 5-year follow-up study in a randomly selected suburban population including 1114 subjects aged ≥18 years living in the suburbs of Beijing. PARTICIPANTS: 118 subjects with T2DM at baseline according to the 1999 WHO criteria were excluded, and 895 subjects attended the follow-up assessment in 2012. The non-diabetic subjects at baseline were classified into two groups: normal glucose tolerance (NGT) group (n=673) and impaired glucose regulation (IGR) group(n=222). The incidence and risk factors of diabetes development in each group were investigated. OUTCOME MEASURES: A structured questionnaire about sociodemographic characteristics, height, weight, waist circumference, hip circumference, blood pressure, oral glucose tolerance test and serum lipid levels. RESULTS: Out of the 895 non-diabetic subjects, 67 developed diabetes with 29 in the NGT group and 38 in the IGR group, respectively, after a 5-year follow-up, producing an overall 5-year cumulative incidence of diabetes of 13%. The incidence of diabetes was 15.5 cases per 1000 person-years, 8.9 cases per 1000 person-years in the NGT group and 35.7 cases per 1000 person-years in the IGR group (p<0.01; RR 4.03; 95% CI 2.58 to 9.29). Binary logistic regression analysis showed that the risk factors for diabetes development included fasting plasma glucose (FPG) in the NGT group, and sex, the waist-to-hip ratio, FPG and diastolic blood pressure (DBP) in the IGR group. CONCLUSIONS: During a mean follow-up of 5.0 years, the incidence of T2DM in the suburbs of Beijing was 15.5 per 1000 person-years. Early prevention of diabetes should focus on IGR subjects. Elevated FPG predicted diabetes development for both NGT and IGR subjects. Female sex, overweight/obesity and DBP are risk factors for diabetes development in IGR subjects.