Journal of Diabetes 8 (2016) 190– 198
O R I G I N A L A RT I C L E
Incidence of type 2 diabetes and number of events attributable to abdominal obesity in China: A cohort study Haifeng XUE,1,2 Chao WANG,1 Ying LI,1 Jichun CHEN,1 Ling YU,3 Xiaoqing LIU,4 Jianxin LI,1 Jie CAO,1 Ying DENG,5 Dongshuang GUO,6 Xueli YANG,1 Jianfeng HUANG1 and Dongfeng GU1 Department of Epidemiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 2Department of Food and Environment, School of Public Health, Qiqihar Medical University, Qiqihar, 3 Fujian Provincial People’s Hospital, Fuzhou, 4Guangdong Provincial People’s Hospital and Cardiovascular Institute, Guangzhou, 5Sichuan Centre for Disease Control and Prevention, Chengdu, and 6Yuxian People’s Hospital, Yuxian, China 1
Correspondence Dongfeng Gu, Department of Epidemiology, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, no. 167, Beilishi Road, Xicheng District, Beijing 100037, China. Tel.: +86 10 68331752 Fax: +86 10 88363812 Email: [email protected] Received 17 August 2014; revised 28 December 2014; accepted 10 January 2015. doi: 10.1111/1753-0407.12273
Abstract Background: The aim of the present study was to estimate the incidence of type 2 diabetes (T2D) and the number of diabetes events attributable to abdominal obesity in China. Methods: A cohort study was conducted in a sample of 24 996 Chinese adults aged 35–74 years, with 19.9% of subjects lost to follow-up. Waist circumference (WC) was measured at baseline in 1998 and 2000–01, and abdominal obesity was defined as WC ≥ 90 cm in men and ≥80 cm in women. Information on incident diabetes was collected during follow-up in 2007–08. We estimated the number of T2D events attributed to abdominal obesity using confounder-adjusted population-attributable risk, incidence of diabetes, and the population size of China in 2010. Results: After a mean follow-up of 8.0 years, the age-standardized incidence of T2D was 9.6 and 9.2 per 1000 person-years in men and women, respectively. Abdominal obesity accounted for 28.1% (95% confidence interval [CI] 14.8%, 40.5%) of incident diabetes among men and 41.2% (95% CI 28.3%, 52.6%) among women using the diagnostic criteria of abdominal obesity recommended by the International Diabetes Federation. We estimated that, in 2010, 2.4 (95% CI 1.5, 3.2) million diabetes events were attributable to abdominal obesity: 1.0 (95% CI 0.5, 1.4) million in men and 1.4 (95% CI 1.0, 1.8) million in women. Conclusions: Abdominal obesity is a major risk factor for T2D. Strengthening programs and initiatives for preventing and controlling obesity focusing on lifestyle changes should be a priority in the national strategy to reduce diabetes burden in China. Keywords: abdominal obesity, cohort study, incidence, populationattributable risk, type 2 diabetes.
Significant findings of the study: The age-standardized incidence of T2D was more than 9.0 per 1000 person-years in Chinese adults over 35 years of age. The number of incident diabetes related to abdominal obesity was 2.4 million in Chinese adults in 2010. What this study adds: Abdominal obesity is a major risk factor for T2D and accounts for approximately 30% of incident diabetes in adults over 35 years of age in China. Preventing and controlling obesity through lifestyle changes may substantially reduce the diabetes burden in China. 190
© 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
H. XUE et al.
Introduction The prevalence of abdominal obesity is increasing substantially. More than 30% of adults in Europe and America,1–3 and more than 20% in Asia,4,5 have abdominal obesity. In 2009, the prevalence of abdominal obesity was 27.8% and 45.9% in Chinese men and women, respectively.4 Abdominal obesity has become a main public health problem worldwide not only because of its high prevalence, but also because of the concomitant risk of metabolic diseases, such as diabetes.1–8 There has been an increase in the prevalence of diabetes in parallel with the increased prevalence of abdominal obesity. From 2007 to 2010, the prevalence of diabetes in China increased from 9.7% to 11.6%, and the number of adults with diabetes increased from 92.4 to 113.9 million.9,10 The rising prevalence of abdominal obesity is a likely cause for the steady increase in the prevalence of diabetes. Type 2 diabetes (T2D) has been demonstrated to be associated with diet, physical activity, overweight/ obesity, socioeconomic status. and genetic factors.11–14 The relationship between abdominal obesity and diabetes has been well examined in prospective studies, mainly in developed countries.7,8,15–19 For example, the Health Professionals Follow-up Study reported that age-adjusted relative risks of diabetes across quintile of waist circumference (WC) were 1.0, 2.0, 2.7, 5.0 and 12.0.16 However, incident diabetes attributable to abdominal obesity has not been well estimated in the general population, especially in China and other developing countries. Therefore, the aim of the present study was to assess the incidence of T2D, examine the strength of the association between abdominal obesity and diabetes risk, and evaluate the incident diabetes attributable to abdominal obesity in China in 2010, using data from a prospective cohort study conducted in China. These estimates can illuminate the significance of preventing abdominal obesity, especially in developing regions where there are deficient healthcare resources and a substantial disease burden related to abdominal obesity.
Methods This study was approved by the Institutional Review Boards at Fuwai Hospital, Chinese Academy of Medical Sciences, and Peking Union Medical College. All study participants provided written informed consent. Study populations The 27 020 participants in the present study were from two cohorts: (i) the China Multicenter Collaborative Study of Cardiovascular Epidemiology (ChinaMUCA);
Abdominal obesity-attributable diabetes
and (ii) the China Cardiovascular Health Study. ChinaMUCA was initiated in 1998, including 15 clusters that were selected on the basis of the main characteristics of the population in terms of socioeconomic status, geographical location, and dietary patterns. Approximately 1000 subjects aged 35–59 years (50% women) were sampled in each cluster. The China Cardiovascular Health Study was a cross-sectional study of cardiovascular disease risk factors conducted in adults aged 35–74 years in 2000–01. A four-stage stratified sampling method was used to select a nationally representative sample of the general population. The study design and methods of ChinaMUCA20 and China Cardiovascular Health Study21 have been described in detail elsewhere. Baseline examination Briefly, baseline data were collected in examination centers at local health stations and community clinics or by home visits. A standard questionnaire assessing demographic characteristics, education level, lifestyle (e.g. smoking, drinking, and work-related physical activity), medical history, and other risk factors was administered by trained research staff. Cigarette smokers were defined as those who reported having smoked at least 400 cigarettes or 0.5 kg tobacco leaves during their lifetime or 1 cigarette per day for 1 year or more. Alcohol consumption was defined as drinking alcohol at least once a week during the past year. High school graduation was defined as having had 12 or more years of schooling. Work-related physical activity was assessed on the basis of subjects’ occupation. After the interview, each of the participants was then invited to undertake a physical examination. Waist circumference (WC) was measured twice using a standard tape horizontally 1 cm above the navel over light clothing in standing subjects to the nearest 0.5 cm; the mean of the two WC recordings was used for the final analysis. Abdominal obesity was defined as WC ≥ 90 cm in men and ≥80 cm in women using criteria recommended by the International Diabetes Federation (IDF) for Chinese adults22 or WC ≥ 90 cm in men and ≥85 cm in women using criteria recommended by the Chinese Diabetes Society (CDS).23 Blood pressure was taken three times at 30-s intervals; the mean of the three blood pressure recordings was used for analysis. Hypertension was defined as mean systolic blood pressure (SBP) ≥ 140 mmHg and/or mean diastolic blood pressure (DBP) ≥ 90 mmHg and/or self-reported use of antihypertensive medication within the past 2 weeks. In the central laboratory (Fuwai Hospital, Beijing, China), overnight fasting blood samples were taken to
© 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
191
Abdominal obesity-attributable diabetes
H. XUE et al.
measure blood glucose, total cholesterol, triglycerides, and high-density lipoprotein cholesterol (HDL-C) on a Hitachi 7060 Clinical Analyzer (Hitachi HighTechnologies, Tokyo, Japan).24 According to American Diabetes Association diagnostic criteria,25 diabetes was defined as fasting glucose levels ≥7.0 mmol/L and/or the use of insulin or oral hypoglycemic agents and/or a selfreported history of diabetes. Impaired fasting glucose was defined as fasting glucose levels ≥6.1 mmol/L and
O R I G I N A L A RT I C L E
Incidence of type 2 diabetes and number of events attributable to abdominal obesity in China: A cohort study Haifeng XUE,1,2 Chao WANG,1 Ying LI,1 Jichun CHEN,1 Ling YU,3 Xiaoqing LIU,4 Jianxin LI,1 Jie CAO,1 Ying DENG,5 Dongshuang GUO,6 Xueli YANG,1 Jianfeng HUANG1 and Dongfeng GU1 Department of Epidemiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 2Department of Food and Environment, School of Public Health, Qiqihar Medical University, Qiqihar, 3 Fujian Provincial People’s Hospital, Fuzhou, 4Guangdong Provincial People’s Hospital and Cardiovascular Institute, Guangzhou, 5Sichuan Centre for Disease Control and Prevention, Chengdu, and 6Yuxian People’s Hospital, Yuxian, China 1
Correspondence Dongfeng Gu, Department of Epidemiology, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, no. 167, Beilishi Road, Xicheng District, Beijing 100037, China. Tel.: +86 10 68331752 Fax: +86 10 88363812 Email: [email protected] Received 17 August 2014; revised 28 December 2014; accepted 10 January 2015. doi: 10.1111/1753-0407.12273
Abstract Background: The aim of the present study was to estimate the incidence of type 2 diabetes (T2D) and the number of diabetes events attributable to abdominal obesity in China. Methods: A cohort study was conducted in a sample of 24 996 Chinese adults aged 35–74 years, with 19.9% of subjects lost to follow-up. Waist circumference (WC) was measured at baseline in 1998 and 2000–01, and abdominal obesity was defined as WC ≥ 90 cm in men and ≥80 cm in women. Information on incident diabetes was collected during follow-up in 2007–08. We estimated the number of T2D events attributed to abdominal obesity using confounder-adjusted population-attributable risk, incidence of diabetes, and the population size of China in 2010. Results: After a mean follow-up of 8.0 years, the age-standardized incidence of T2D was 9.6 and 9.2 per 1000 person-years in men and women, respectively. Abdominal obesity accounted for 28.1% (95% confidence interval [CI] 14.8%, 40.5%) of incident diabetes among men and 41.2% (95% CI 28.3%, 52.6%) among women using the diagnostic criteria of abdominal obesity recommended by the International Diabetes Federation. We estimated that, in 2010, 2.4 (95% CI 1.5, 3.2) million diabetes events were attributable to abdominal obesity: 1.0 (95% CI 0.5, 1.4) million in men and 1.4 (95% CI 1.0, 1.8) million in women. Conclusions: Abdominal obesity is a major risk factor for T2D. Strengthening programs and initiatives for preventing and controlling obesity focusing on lifestyle changes should be a priority in the national strategy to reduce diabetes burden in China. Keywords: abdominal obesity, cohort study, incidence, populationattributable risk, type 2 diabetes.
Significant findings of the study: The age-standardized incidence of T2D was more than 9.0 per 1000 person-years in Chinese adults over 35 years of age. The number of incident diabetes related to abdominal obesity was 2.4 million in Chinese adults in 2010. What this study adds: Abdominal obesity is a major risk factor for T2D and accounts for approximately 30% of incident diabetes in adults over 35 years of age in China. Preventing and controlling obesity through lifestyle changes may substantially reduce the diabetes burden in China. 190
© 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
H. XUE et al.
Introduction The prevalence of abdominal obesity is increasing substantially. More than 30% of adults in Europe and America,1–3 and more than 20% in Asia,4,5 have abdominal obesity. In 2009, the prevalence of abdominal obesity was 27.8% and 45.9% in Chinese men and women, respectively.4 Abdominal obesity has become a main public health problem worldwide not only because of its high prevalence, but also because of the concomitant risk of metabolic diseases, such as diabetes.1–8 There has been an increase in the prevalence of diabetes in parallel with the increased prevalence of abdominal obesity. From 2007 to 2010, the prevalence of diabetes in China increased from 9.7% to 11.6%, and the number of adults with diabetes increased from 92.4 to 113.9 million.9,10 The rising prevalence of abdominal obesity is a likely cause for the steady increase in the prevalence of diabetes. Type 2 diabetes (T2D) has been demonstrated to be associated with diet, physical activity, overweight/ obesity, socioeconomic status. and genetic factors.11–14 The relationship between abdominal obesity and diabetes has been well examined in prospective studies, mainly in developed countries.7,8,15–19 For example, the Health Professionals Follow-up Study reported that age-adjusted relative risks of diabetes across quintile of waist circumference (WC) were 1.0, 2.0, 2.7, 5.0 and 12.0.16 However, incident diabetes attributable to abdominal obesity has not been well estimated in the general population, especially in China and other developing countries. Therefore, the aim of the present study was to assess the incidence of T2D, examine the strength of the association between abdominal obesity and diabetes risk, and evaluate the incident diabetes attributable to abdominal obesity in China in 2010, using data from a prospective cohort study conducted in China. These estimates can illuminate the significance of preventing abdominal obesity, especially in developing regions where there are deficient healthcare resources and a substantial disease burden related to abdominal obesity.
Methods This study was approved by the Institutional Review Boards at Fuwai Hospital, Chinese Academy of Medical Sciences, and Peking Union Medical College. All study participants provided written informed consent. Study populations The 27 020 participants in the present study were from two cohorts: (i) the China Multicenter Collaborative Study of Cardiovascular Epidemiology (ChinaMUCA);
Abdominal obesity-attributable diabetes
and (ii) the China Cardiovascular Health Study. ChinaMUCA was initiated in 1998, including 15 clusters that were selected on the basis of the main characteristics of the population in terms of socioeconomic status, geographical location, and dietary patterns. Approximately 1000 subjects aged 35–59 years (50% women) were sampled in each cluster. The China Cardiovascular Health Study was a cross-sectional study of cardiovascular disease risk factors conducted in adults aged 35–74 years in 2000–01. A four-stage stratified sampling method was used to select a nationally representative sample of the general population. The study design and methods of ChinaMUCA20 and China Cardiovascular Health Study21 have been described in detail elsewhere. Baseline examination Briefly, baseline data were collected in examination centers at local health stations and community clinics or by home visits. A standard questionnaire assessing demographic characteristics, education level, lifestyle (e.g. smoking, drinking, and work-related physical activity), medical history, and other risk factors was administered by trained research staff. Cigarette smokers were defined as those who reported having smoked at least 400 cigarettes or 0.5 kg tobacco leaves during their lifetime or 1 cigarette per day for 1 year or more. Alcohol consumption was defined as drinking alcohol at least once a week during the past year. High school graduation was defined as having had 12 or more years of schooling. Work-related physical activity was assessed on the basis of subjects’ occupation. After the interview, each of the participants was then invited to undertake a physical examination. Waist circumference (WC) was measured twice using a standard tape horizontally 1 cm above the navel over light clothing in standing subjects to the nearest 0.5 cm; the mean of the two WC recordings was used for the final analysis. Abdominal obesity was defined as WC ≥ 90 cm in men and ≥80 cm in women using criteria recommended by the International Diabetes Federation (IDF) for Chinese adults22 or WC ≥ 90 cm in men and ≥85 cm in women using criteria recommended by the Chinese Diabetes Society (CDS).23 Blood pressure was taken three times at 30-s intervals; the mean of the three blood pressure recordings was used for analysis. Hypertension was defined as mean systolic blood pressure (SBP) ≥ 140 mmHg and/or mean diastolic blood pressure (DBP) ≥ 90 mmHg and/or self-reported use of antihypertensive medication within the past 2 weeks. In the central laboratory (Fuwai Hospital, Beijing, China), overnight fasting blood samples were taken to
© 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
191
Abdominal obesity-attributable diabetes
H. XUE et al.
measure blood glucose, total cholesterol, triglycerides, and high-density lipoprotein cholesterol (HDL-C) on a Hitachi 7060 Clinical Analyzer (Hitachi HighTechnologies, Tokyo, Japan).24 According to American Diabetes Association diagnostic criteria,25 diabetes was defined as fasting glucose levels ≥7.0 mmol/L and/or the use of insulin or oral hypoglycemic agents and/or a selfreported history of diabetes. Impaired fasting glucose was defined as fasting glucose levels ≥6.1 mmol/L and
