Objective  The aim of this study was to determine whether lifestyle status affects the insulin resistance index or serum adiponectin level, which may be responsible for the development of insulin resistance syndrome that sometimes indicates lifestyle-related diseases.
  Methods  A cross-sectional study was performed.
  Patients  Seven hundred thirty-eight males aged 30 to 65 years who had regular health checkups in our office were enrolled. Each subject’s lifestyle status, level of serum adiponectin, and serum insulin level were assessed by a self-administered questionnaire based on Breslow’s lifestyle index, enzyme-linked immunosorbent assay, and radioimmunoassay, respectively. Moreover, their insulin resistance indexes were assessed by the homeostasis model.
  Results  One-way ANOVA demonstrated an inverse correlation between Breslow’s index and the logarithmic insulin resistance index (p<0.0001), and a tendency of a correlation between Breslow’s index and the logarithmic serum adiponectin level (p=0.0681). Multiple logistic regression analyses demonstrated that, among the seven lifestyle items in Breslow’s index, body mass index of more than 26.1 kg/m² and insufficient exercise style had 8.9 times and 2.1 times the risks for insulin resistance and the former also had 3.2 times the risk for hypoadiponectinemia. Partial correlation coefficients of these correlations were 0.336 (p<0.0001), 0.107 (p=0.0013), and 0.165, (p<0.0001), respectively.
  Conclusion  Unhealthy lifestyles may cause hypoadiponectinemia and insulin resistance followed by insulin resistance syndrome, i.e. lifestyle-related diseases. These findings present reasonable explanations for the relationships between lifestyles and lifestyle-related diseases. Improvement of unhealthy lifestyles, especially the control of body weight, may have beneficial effects against the development of lifestyle-related diseases.