Inverse relationship of serum adiponectin concentration with type 2 diabetes mellitus incidence in middle-aged Japanese workers: six-year follow-up

Background It was suggested that inflammation may mediate or modify biological effects of adiponectin. Few studies examined the association between circulating adiponectin levels and type 2 diabetes (T2DM) while controlling for variables related to inflammation. In addition, East Asians were reported to have lower adiponectin levels but higher diabetes prevalence at a given degree of obesity than Caucasians, raising some possibility that the adiponectindiabetes association may differ by race. Therefore, we prospectively investigated the associations with a number of covariates including C-reactive protein and smoking status in a cohort of Japanese workers aged 3566?years. Methods Serum adiponectin concentration and other covariates were obtained in 2002 for 3008 civil servants free of T2DM at baseline in urban/suburban Japan. T2DM incidence was defined as the year when annually assessed fasting blood glucose level first exceeded 126?mg/dL or self-reported initiation of medication through 2007. T2DM incidence was examined in relation to the adiponectin quintile. Results Age- and sex-adjusted homeostasis model assessment insulin resistance was inversely associated with adiponectin quintiles at baseline. During six years of follow-up, 164 individuals developed T2DM. In a fully adjusted model, hazard ratios (95% confidence intervals) of T2DM in Q2 to Q5 compared with that in Q1 were 0.62 (0.410.94), 0.44 (0.250.77), 0.40 (0.200.78) and 0.85 (0.481.49), respectively. Conclusions Low adiponectin was related to increased incidence of T2DM independent of baseline levels of blood glucose, insulin and C-reactive protein as well as other confounding variables in middle-aged Japanese. Whether high adiponectin is linearly associated with decreased T2DM risk needs further investigation. Copyright (C) 2012 John Wiley & Sons, Ltd.