Adiponectin expression in adipose tissue is reduced in first-degree relatives of type 2 diabetic patients

Adiponectin is suggested to be an important mediator of insulin resistance. Therefore, we investigated the association between adiponectin and insulin sensitivity in 22 healthy first-degree relatives (FDR) to type 2 diabetic patients and 13 matched control subjects. Subcutaneous adipose tissue biopsies were taken before and after a hyperinsulinemic euglycemic clamp. FDR subjects were insulin resistant, as indicated by a reduced M value (4.44 vs. 6.09 mg x kg(-1) x min(-1), P < 0.05). Adiponectin mRNA expression was 45% lower in adipose tissue from FDR compared with controls (P < 0.01), whereas serum adiponectin was similar in the two groups (6.4 vs. 6.6 microg/ml, not significant). Insulin infusion reduced circulating levels of adiponectin moderately (11-13%) but significantly in both groups (P < 0.05). In the control group, adiponectin mRNA levels were negatively correlated with fasting insulin (P < 0.05) and positively correlated with insulin sensitivity (P < 0.05). In contrast, these associations were not found in the FDR group. In conclusion, FDR have reduced adiponectin mRNA in subcutaneous adipose tissue but normal levels of circulating adiponectin. Adiponectin mRNA levels are positively correlated with insulin sensitivity in control subjects but not in FDR. These findings indicate dysregulation of adiponectin gene expression in FDR.