title: Community-based study on summer-winter difference in insulin resistance in Kin-Chen, Kinmen, Taiwan.
abstract: BACKGROUND
  The aim of this community-based study was to explore the summer-winter difference in insulin resistance in Kin-Chen, Kinmen.
  
  
  METHODS
  A total of 2,412 residents aged 40 and over was enrolled in a mass survey in Kin-Chen, Kinmen, by the Yang-Ming Crusade, a volunteer organization of well-trained medical students from National Yang-Ming University. All participants were investigated in winter (first phase, January and February, before Chinese New Year) and summer (secondary phase, July and August) in 2002. Structured questionnaires, demographic and physical data, lifestyle, and blood chemistry parameters were collected.
  
  
  RESULTS
  Higher levels of fasting insulin, HOMA-insulin resistance and triglycerides, but lower levels of high-density lipoprotein cholesterol were found in summer than in winter. The prevalence of metabolic syndrome was higher in summer than in winter, with differences of 7.7% in both genders (p = 0.0092 in men, p = 0.0037 in women). Body mass index (BMI), age and physical activity were significantly correlated with metabolic syndrome. After controlling for BMI and other risk profiles, summer was independently and positively associated with fasting insulin and insulin resistance regardless of metabolic syndrome.
  
  
  CONCLUSIONS
  Fasting insulin, insulin resistance and prevalence of metabolic syndrome were higher in summer than in winter. BMI and season were 2 major determinants of the variation in fasting insulin. The contextual impacts of seasonal variation in shaping metabolic syndrome or insulin resistance in populations need to be reemphasized.
authors.affiliation: Community Medicine Research Center and Institute of Public Health, National Yang-Ming University, and Kin-Nin Health Center, Kinmen, Taipei, Taiwan, ROC.
authors.forename: Shui-Hu
authors.initials: SH
authors.lastname: Chen
authors.forename: Shao-Yuan
authors.initials: SY
authors.lastname: Chuang
authors.forename: Kuan-Chia
authors.initials: KC
authors.lastname: Lin
authors.forename: Shih-Tzer
authors.initials: ST
authors.lastname: Tsai
authors.forename: Pesus
authors.initials: P
authors.lastname: Chou
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D015992:Body Mass Index; D008076:Cholesterol, HDL / Q000097:blood; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D016015:Logistic Models; D008297:Male; D024821:Metabolic Syndrome / Q000453:epidemiology; D008875:Middle Aged; D012621:Seasons; D013624:Taiwan / Q000453:epidemiology
chemical_list: D008076:Cholesterol, HDL