| Part One:Diabetes incidence in Chinese:contributions of overweight and obesityBackground and objectiveOverweight and obesity is a global public health problem. During the past decades, the prevalence of overweight and obesity increased significantly among Chinese. Notably, the prevalence of diabetes has been increasing sharply with rapid economic development, nutrition transition, changes in lifestyle and so on. Association between overweight/obesity and the risk of diabetes has been well examined mainly in developed countries. However, few cohort studies were conducted in China. We aimed to investigate the association between overweight, obesity and incidence of diabetes among Chinese adults, and estimate the population attributable risks (PARs) and number of incident diabetes attributable to overweight and obesity in China.Subjects and methodsWe conducted a cohort study in a sample of25025Chinese adults aged35-74years. The survey was initiated in1998and2000-2001, and investigators collected data on body mass index (BMI was calculated as weight/height squared) and other risk factors at a baseline examination using a standard protocol. Follow-up evaluation was conducted in2007-2008. In the current study, the definition of overweight and obesity was based on the World Health Organization (WHO) criteria (BMI cutoff points:25.0-29.9kg/m2for overweight,>30kg/m2for obesity) or Working Group on Obesity in China (BMI cutoff points:24.0-27.9kg/m2for overweight,≥28kg/m2for obesity). The association between overweight, obesity and risk of diabetes were estimated by Cox proportional hazards models. PAR of overweight and obesity was calculated by pooled logistic regression model. Thereafter, the number of diabetes cases attributed to overweight and obesity were estimated using PAR, incidence and the population size of China in2010.ResultsDuring a mean follow-up of8.0years,1099participants (536men,563women) developed diabetes. After adjustment for geographic region, urbanization, educational status, tobacco smoking, alcohol drinking, work-related physical activity, family history of diabetes, impaired fasting glucose, hypertension and dyslipidemia, overweight and obesity were found to be significantly associated with increased risk of incident diabetes in Chinese men and women. There was a significant, dose-response association between BMI and incidence of diabetes in both men and women (P<0.001for trend). According to the WHO criteria, the PAR for incident diabetes attributable to overweight was accounted for28.3%(95%confidence interval [CI]:20.1-36.2) among men and31.3%(25.5-36.9) among women, respectively. The corresponding PAR of obesity was accounted for10.1%(6.0-14.2) among men and16.8%(12.0-21.6) among women. We estimated that in2010, a total of3.32(2.47-4.24) million incident diabetes were attributable to overweight and obesity in China:1.13(0.8-1.44) million in men and1.19(0.97-1.41) million in women were attributable to overweight,0.45(0.24-0.57) million in men and0.55(0.46-0.82) million in women were attributable to obesity. According to the Working Group on Obesity in China, the PAR for incident diabetes attributable to overweight was accounted for24.7%(18.6-30.6) among men and21.3%(17.0-25.5) among women, respectively. The corresponding PAR of obesity was accounted for21.3%(14.6-27.7) among men and31.0%(23.6-38.0) among women. A total of3.66(2.78-4.61) million incident diabetes were attributable to overweight and obesity in China:1.00(0.75-1.23) million in men and0.80(0.60-0.91) million in women were attributable to overweight,0.76(0.59-1.12) million in men and1.10(0.84-1.35) million in women were attributable to obesity.ConclusionOur study documented that incident diabetes is mainly attributable to overweight and obesity which are strong modifiable risk factors for diabetes. More than3million incidents diabetes could have been prevented by eliminating overweight and obesity in adults aged35-74years in China in2010. Preventing excessive weight gain is crucial for reducing diabetes burden in China. Part Two:Study on major risk factors of incident diabetes in Chinese adultsBackground and objectiveThe prevalence of diabetes has increased rapidly worldwide,especially in developing countries. According to the prediction of the International Diabetes Federation, there will be about591.9million patients with diabetes all over the world by2035, most of which will be in China and Africa. Diabetes has become a serious global health problem. Nowadays, risk factors for diabetes have been prospectively assessed in developed countries. In China, risk factors for diabetes have been explored mainly in cross-sectional studies but few in prospective studies. The purpose of the present study was to explore the risk factors of diabetes in a prospective cohort of Chinese adults.Subjects and methodsWe conducted a cohort study in a sample of25025Chinese adults aged35-74years. The survey was initiated in1998and2000-2001, and investigators collected data on demographic characteristics, behavior risk factors, family history of diabtetes, anthropometric (height, weight and blood pressure), and laboratory measurements (fasting glucose, total cholesterol, triglyceride, and high density lipoprotein cholesterol) at a baseline examination using a standard protocol. Follow-up evaluation was conducted in2007-2008. Diabetes was defined as a fasting glucose concentration≥126mg/dL, self-reported history of diabetes, the use of insulin or oral hypoglycemic agents or death certificates listing diabetes as an underlying or contributing cause of death. Cox regression models were used to examine estimated hazard ratios (HRs) with95%confidence intervals (CIs) for incident diabetes. Age was used as the time-scale in all time-to-event analysis. We examined the associations between each risk factor and incident diabetes, and then determined independent risk factors for incident diabetes by including all variables in multivariable Cox proportional hazards regression models.ResultsDuring a mean follow-up of8.0years,1099participants (536men,563women) developed diabetes. Among men, the independent risk factors of incident diabetes were overweight [hazard ratio (HR):HR:2.50;95%CI:2.04-3.07), obesity (HR:4.59;95%CI:3.28-6.44), impaired fasting glucose (HR:3.06;95%CI:2.47-3.79), family history of diabetes (HR:1.84;95%CI:1.37-2.47), dyslipidemia (HR:1.69;95%CI:1.41-2.04) and tobacco smoking (HR:1.26;95%CI:1.03-1.55). Among women, the independent risk factors of incident diabetes were overweight (HR:2.54;95%CI:2.10-3.09), obesity (HR:4.51;95%CI:3.44-5.91), impaired fasting glucose (HR:4.06;95%CI:3.32-4.97), family history of diabetes (HR:2.16;95%CI:1.66-2.81), dyslipidemia (HR:1.34;95%CI: 1.12-1.59).ConclusionOur study demonstrated that the independent risk factors of incident diabetes were overweight, obesity, impaired fasting glucose, family history of diabetes, dyslipidemia and tobacco smoking among men. All predictors except smoking were also independently contributed to the development of diabetes among women. Diabetes is a major public health problem, and effective prevention and control programs are urgently needed in China. |
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