title: Low muscle mass and risk of type 2 diabetes in middle-aged and older adults: findings from the KoGES.
abstract: Asians have a propensity to develop type 2 diabetes with a lower BMI than Western populations. This discrepancy may be due to differences in body fat and muscle mass for a given BMI. However, unlike adiposity, it is unclear whether muscle mass affects the risk of type 2 diabetes in Asian populations.
  
  
  
  We conducted a 2-yearly prospective assessment of 6895 participants who were free of diabetes at the baseline examination as part of the Korean Genome Epidemiology Study. The muscle mass index (MMI) was defined as the weight-adjusted appendicular skeletal muscle mass. Using Cox regression models, we evaluated the association between MMI and the risk of developing type 2 diabetes across sex-specific tertiles of MMI. Low muscle mass was defined as the sex-specific lowest tertile of MMI. Main covariates included age, sex, urban or rural residence, family history of diabetes, hypertension, smoking status, education level, monthly income, physical activity, alcohol consumption and diet. In addition, body fat mass, waist circumference and BMI were controlled as categorical variables. Obesity was defined as a BMI of ≥25 kg/m2or a waist circumference of ≥90 cm for men and ≥85 cm for women.
  
  
  
  During a median follow-up of 9.06 years, 1336 participants developed type 2 diabetes. At baseline, the mean age was 52.1 years and the mean BMI was 24.4 kg/m2. The mean MMI for men and women was 32.1% and 26.0%, respectively. There was an inverse association between MMI and the risk of type 2 diabetes. Multivariate-adjusted HRs for the risk of developing type 2 diabetes were 2.05 (95% CI 1.73, 2.43), 1.39 (95% CI 1.17, 1.66) and 1.0 from the lowest to highest sex-specific MMI tertile, with an HR of 1.35 (95% CI 1.26, 1.45) per SD decline in MMI. Further adjustments for fat mass, waist circumference and BMI as categorical variables did not modify the relationship (each p < 0.01). In BMI-stratified analyses, the population-attributable fraction of the lowest tertile of MMI for developing type 2 diabetes was increased by 11.9% in the non-obese group and 19.7% in the obese group.
  
  
  
  Low muscle mass as defined by MMI was associated with an increased risk of type 2 diabetes, independent of general obesity, in middle-aged and older Korean adults.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Bucheon St Mary's Hospital, College of Medicine, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Jang Won
authors.initials: JW
authors.lastname: Son
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Bucheon St Mary's Hospital, College of Medicine, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Seong Su
authors.initials: SS
authors.lastname: Lee
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Bucheon St Mary's Hospital, College of Medicine, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Sung Rae
authors.initials: SR
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Bucheon St Mary's Hospital, College of Medicine, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Soon Jib
authors.initials: SJ
authors.lastname: Yoo
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Bong Yun
authors.initials: BY
authors.lastname: Cha
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University Medical Center, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Ho Young
authors.initials: HY
authors.lastname: Son
authors.affiliation: Department of Preventive Medicine, Ajou University School of Medicine, 5 Wonchon-Dong, Youngtong-Gu, Suwon, 443-721, Korea. chnaha@ajou.ac.kr.
authors.forename: Nam H
authors.initials: NH
authors.lastname: Cho
mesh_terms: D000367:Age Factors; D044466:Asian People; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology* / Q000378:metabolism* / Q000503:physiopathology; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D009765:Obesity / Q000378:metabolism / Q000503:physiopathology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D055105:Waist Circumference / Q000502:physiology
keywords: BMI; Obesity; Skeletal muscle; Type 2 diabetes mellitus