| ObjectivesWe aimed to explore the association between sedentary time and Type 2 diabetes mellitus(T2DM)and the interaction between sedentary time and obesity indicators on T2DM based on the rural population in Henan,China.MethodsWe used the cluster random sampling method to select residents(? 18 years)in Tiemen Town and Cijian Town,Xin'an County,Henan Province during 2007-2008,and a total of 20,194 participants were investigated in the baseline survey.Follow-up survey was conducted in July to August of 2013 and July to October of 2014,with 17,265 participants completed(response rate:85.5%).Participants with T2DM(n=1696)and type 1 diabetes mellitus(T1 DM)(n=14),deaths during follow-up(n=913),and unknown status of T2DM at the end of follow-up(n=2,556)were excluded,and a total of 12,284(men:4,668,women:7,616)participants were analyzed.Sedentary time was collected using questionnaires and divided into 4 groups:<4,4-8,8-12,and>12 hours/day.We used the Cox proportional hazard regression model to analyze the hazard ratio(HR)and 95%confidence interval(Cl)of sedentary time and risk of T2DM.Stratified analyses were performed by sex,age,smoking status,physical activity level,obesity(general obesity and central obesity),blood pressure and lipid status.The multiplicative interaction term of sedentary time and obesity indicators were included in the Cox proportional hazard regression model for multiplicative interaction analyses.Then,method proposed by Anderson and the Excel software was used to analyze the additive interaction between sedentary time and obesity indicators.In addition,we also conducted sensitivity analyses to evaluate the robustness of the results by excluding participants who developed T2DM in the first two follow-up years.Results1.A total of 12,284 participants were included in this study.Between participants included and those who were lost to follow-up,the difference of sex,family history of diabetes,sedentary time,and high-density lipoprotein cholesterol(HDL-C)were statistically unsignificant(P>0.05).Age,sedentary time,proportion of family history of diabetes,body mass index(BMI),waist circumference(WC),fasting plasma glucose(FPG),systolic blood pressure(SBP),diastolic blood pressure(DBP),total cholesterol(TC),triglyceride(TG),and low-density lipoprotein cholesterol(LDL-C)levels in T2DM patients were higher than those in non-T2DM patients,and HDL-C levels were lower than those of non-T2DM patients(all P<0.05).With the increase of sedentary time,age,T2DM incidence,BMI,WC,SBP,DBP,TG,and LDL-C all increased,while the proportion of alcohol drinkers and marriage/cohabitation decreased(Ptrend<0.05).2.We followed up 73,403.52 person-years(mean 6 years),and identified 847 new T2DM patients(318 men and 529 women)during follow-up.The cumulative incidence and incidence density were 6.90%and 11.54 per 1,000 person-years.Participants with sedentary time less than 4 hours/day had the lowest cumulative incidence(%)and incidence density(per 1,000 person-years),which were 4.95(95%CI:3.70-6.46)and 8.29(95%CI:6.18-10.88),respectively,while those who had sedentary time over 12 hours/day were 8.29(95%CI:6.98-9.76)and 14.05(95%CI:11.77-16.64)respectively.Results of Cox proportional hazard regression model showed that after adjusting for baseline age,sex,smoking,alcohol consumption,physical activity level,education level,marital status,occupation,family history of diabetes,BMI,FPG,SBP,DBP,TC,TG,HDL-C and LDL-C,the the risk of T2DM increased by 45%(HR:1.45,95%CI:1.01-2.12),53%(HR:1.53,95%CI:1.02-2.22)and 95%(HR:1.95,95%CI:1.29-2.96),respectively in 4-8,8-12 and>12 hours/day sedentary time groups,compared with?4 hours/day group.With the increase of sedentary time,the risk of T2DM increased gradually(Pt,ena<0.05).For each 1-h/day increase in sedentary time,the risk of T2DM increased by 2%(HR:1.02,95%CI:1.00-1.05).3.The results of stratified analyses showed that compared with shorter sedentary time(<4 hours/day),after adjusting for possible confounding factors,the risk of T2DM in the 4-8,8-12 and>12 hours/day sedentary groups increased in men,baseline smokers,light physical activity levels,central obesity,and hypertension population.In people aged>60 years and general obese,the risk of T2DM in 8-12 and?12 hours/day of sedentary time groups was increased.In people aged<60 years,non-smokers,moderate physical activity level,non-central obese,non-hypertensive,normal blood lipids and dyslipidemia population,the sedentary time>12 hours/day increased the risk of T2DM.There was no statistically significance between sedentary time and risk of T2DM among women,heavy physical activity levels and non-general obesity population.4.The analyses of the multiplicative interaction between sedentary time and BMI showed that risk of T2DM from the interaction between sedentary time and BMI was 3.1%(HR=1.031,95%CI:1.003-1.058).The additive interaction analysis showed that compared with people with sedentary time<12 hours/day and BMI<28kg/m2,risk of T2DM increased by 178%(HR=2.78,95%CI:1.93-3.99)in people with long sedentary time(? 12 hours/day)and BMI? 28kg/m2.The multiplicative interaction analysis between sedentary time and WC showed that risk of T2DM from the interaction between sedentary time and WC was 2.1%(HR=].021,95%CI:1.001-1.043).The additive interaction analysis showed that compared with people with sedentary time<12 hours/day and WC<90 cm(men)or WC<80 cm(women),risk of T2DM increased by 113%(HR=2.13,95%CI:1.56-2.91)in people with long sedentary time(? 12 hours/day)and WC>90 cm(men)or WC<80 cm(women).5.Results of sensitivity analyses showed that there was no significant change in the association between sedentary time and risk of T2DM after excluding participants who developed T2DM in the first two follow-up years.Conclusions1.We found that with the increase of sedentary time,risk of T2DM increased.In the sedentary time group<4,4-8,8-12,and? 12 hours/day,the cumulative incidence and density of T2DM both were highest in the? 12 hours/day group.2.The association between sedentary time and T2DM was stable in men,smokers,light physical activity level,central obesity and hypertension population,but there was no statistically significant relationship among women,heavy physical activity level and non-general obesity population.3.There was a multiplicative interaction between sedentary time and obesity indicators(BMI and WC)in this population,which increased the risk of T2DM,and the additive interaction was not statistically significant. |
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