High molecular weight multimer form of adiponectin as a useful marker to evaluate insulin resistance and metabolic syndrome in Japanese men.

Adiponectin is an adipocyte-specific secretory protein that possesses antidiabetic and antiatherosclerotic properties. Recent studies have demonstrated that the high molecular weight (HMW) multimer form is the active form of this protein. In patients with type 2 diabetes mellitus, HMW-total adiponectin ratio was reported to be a more useful marker than total adiponectin in the prediction of insulin resistance and metabolic syndrome. In the present study of healthy Japanese male subjects without any medication, we investigated the hypothesis that measuring only HMW adiponectin may be as effective as HMW-total ratio to predict insulin resistance and/or metabolic syndrome. This was a working community-based cross-sectional study of 637 male subjects aged 30 to 65 years. Total and HMW adiponectin concentrations in serum were measured by enzyme-linked immunosorbent assay using commercially available kits. Serum HMW adiponectin level was inversely correlated with homeostasis model assessment of insulin resistance (HOMA-IR) (r = -0.375, P < .0001) even after adjustment for age and body mass index (r' = -0.245, P < .0001). When we divided the study subjects into quartile groups with equal numbers of subjects, HOMA-IR in the 4 groups based on serum HMW adiponectin level was significantly different (P < .01). Metabolic syndrome score in the 4 groups based on serum HMW adiponectin level was also significantly different (P < .01). Area under the curve of receiver operator characteristic curves of HMW adiponectin (0.73) to evaluate the presence of insulin resistance (HOMA-IR >2.5) was larger than that of total adiponectin (0.68) or HMW-total ratio (0.70). Area under the curve of receiver operator characteristic curves of HMW adiponectin (0.70) to evaluate the presence of metabolic syndrome (body mass index-based modified criteria) was also larger than that of total adiponectin (0.65), but equal to that of HMW-total ratio (0.70). These results suggest that simply measuring HMW adiponectin may be as effective as HMW-total ratio to evaluate the presence of insulin resistance and metabolic syndrome, at least in nondiabetic subjects who are not receiving any medication.