Prospective Cohort Study Of Chinese Adults With Abdominal Obesity And Diabetes Relations

Part One:Incidence of diabetes and association between abdominal obesity and risk of diabetes among Chinese adults:a prospective cohort studyBackground and ObjectiveAbdominal obesity and diabetes have become major public health problems around the world. We aimed to estimate the incidence of diabetes and the number of incident cases attributable to abdominal obesity among Chinese men and women.Design and MethodsWe conducted a prospective cohort study in a sample of25025Chinese adults free of diabetes, aged35-74years. Waist circumference (WC) and other anthropometric measurements were measured using the same method, and information on sociodemography, medical history and life style was collected at baseline in1998and2000-2001. Abdominal obesity was defined as WC>90/80cm (men/women). Follow-up examination was carried out in2007-2008. To ascertain newly developed diabetes, information on diabetes status, use of insulin and oral antidiabetic drugs was collected, and fasting blood was drawn for glucose measurement. Cox regression was used to estimate association between abdominal obesity and risk of diabetes. The number of diabetes cases attributed to abdominal obesity was evaluated by using multivariable-adjusted population-attributable risk, incidence of diabetes and the population size of China in2010.ResultsDuring a mean follow-up of8.0years, age-standardized incidence of diabetes was9.6and9.2per1000person-years in Chinese men and women aged35-74years, respectively. Multivariate-adjusted HR (95%CI) for diabetes per centimeter increase in WC was1.06(1.05,1.07) in both men and women. With the group of WC<90cm as reference group, HR (95%CI) of the group of WC:90-94cm,95-99cm and≥100cm for diabetes was2.13(1.68,2.70),2.71(2.01,3.65) and3.33(2.41,4.59) in men, respectively (P for trend <0.001); With the group of WC<80cm as reference group, HR (95%CI) of the group of WC:80-84cm,85-89cm and≥90cm for diabetes was1.77(1.38,2.26),2.60(2.04,3.31) and3.36(2.66,4.25) in women, respectively (P for trend<0.001). Abdominal obesity accounted for28.1%(95%confidence interval [CI]:14.8%,40.5%) of incident diabetes among men and41.2%(28.3%,52.6%) among women. It was estimated that in2010,2.4(1.5,3.2) million incident diabetes were attributable to abdominal obesity:1.0(0.5,1.4) million in men and1.4(1.0,1.8) million in women.ConclusionsAbdominal obesity is a major risk factor for diabetes. Strengthening programs and initiatives for preventing obesity focusing lifestyle changes should be a priority in the national strategy to reduce such huge diabetes burden in China. Part Two:Comparison between different measures for abdominal obestiy in predicting risk of diabetes among Chinese adultsBackground and ObjectiveObesity, especially abdominal obesity, is a strong risk factor for diabetes and cardiovascular diseases. However, it remains controversial which can better predict diabetes risk among waist circumference (WC), waist-hip ratio (WHR) or waist-height ratio (WHtR). The aim of this nanlysis is to compare and examine WC, WHR and WHtR in predicting diabetes in Chinese adults.Design and MethodsWe conducted a prospective cohort study in a sample of25025Chinese adults free of diabetes, aged35-74years. WC, hip circumference, height and other anthropometric measures were measured, and information on sociodemography, medical history and life style was also collected at baseline in1998and2000-2001. WHR and WHtR was calculated as WC (cm)/hip circumference (cm) and WC (cm)/height (cm), respectively. Follow-up examination was carried out in2007-2008. To ascertain newly developed diabetes, information on diabetes status, use of insulin and oral antidiabetic drugs was collected, and fasting blood was drawn for glucose measurement. Cox regression was used to estimate association between abdominal obesity and risk of diabetes. Predictive power of different abdominal obesity for diabetes was compared by receiver operating characteristic (ROC) curve. We also evaluated appropriate cut-off values of different abdominal obesity and their sensitivity and specificity.ResultsDuring a mean follow-up of8.0years,1101cases of diabetes (537in men and564in women) occurred. WC, WHR and WHtR all predicted future diabetes and there was a dose-response association between WC, WHR and WHtR and diabetes risk (P for trend<0.001). The multivariable-adjusted HR (95%CI) for diabetes per one standard deviation increase in WC, WHR and WHtR was1.36(1.20,1.54),1.24(1.14,1.33) and1.45(1.24,1.69) in men; and1.30(1.17,1.45),1.17(1.07,1.27) and1.27(1.14,1.42) in women, respectively. In men, there was no significant differences between area under ROC curve (AUC) of WC, WHR, and WHtR in predicting DM. In women, there was statistical evidence that WC (AUC:0.72;95%CI:0.70,0.74) and WHtR (AUC:0.72;95%CI:0.70,0.74) were stronger predictors than WHR (AUC:0.67;95%CI:0.64,0.69)(P<0.001). The optimal cutoff value, sensitivity and specificity of WC were84.9cm,61.3%and69.3%,0.87,73.2%and55.5%for WHR, and0.50,67.6%and63.3%for WHtR in men, respectively; and77.0cm,75.4%and57.8%for WC,0.84,56.9%and67.9%for WHR,, and0.51,67.7%and64.9%for WHtR in women, respectively.ConclusionWC, WHR and WHtR all are strong predictors of abdominal obesity for diabetes risk in Chinese adluts. In women, WC and WHtR are stronger predictors than WHR. The appropriate cutoff value of WC is84.9and77.0cm in men and women, respectively. WC is likely a better predictor of diabetes in clinical and public health practice to control and prevent abdominal obesity and diabetes.