Importance of the high-molecular-mass isoform of adiponectin in improved insulin sensitivity with rosiglitazone treatment in HIV disease

The present study was designed to investigate the relationship of isoforms of adiponectin to insulin sensitivity in subjects with HIV-associated insulin resistance in response to treatment with the thiazolidinedione, rosiglitazone. The two isoforms of adiponectin, HMW (high-molecular-mass) and LMW (low-molecular-mass), were separated by sucrose-gradient-density centrifugation. The amount of adiponectin in gradient fractions was determined by ELISA. Peripheral insulin sensitivity (Rd) was determined with hyperinsulinaemic- euglycaemic clamp, whereas hepatic sensitivity [HOMA (Homoeostasis Model Assessment) %S] was based on basal glucose and insulin values. Treatment with rosiglitazone for 3 months resulted in a significant improvement in the index of hepatic insulin sensitivity (86.4 ± 15% compared with 139 ± 23; P = 0.007) as well as peripheral insulin sensitivity (4.04 ± 0.23 compared with 6.17 ± 0.66 mg of glucose/kg of lean body mass per min; P < 0.001). Improvement in HOMA was associated with increased levels of HMW adiponectin (r = 0.541, P = 0.045), but not LMW adiponectin. The present study suggests that the HMW isoform of adiponectin is important in the regulation of rosiglitazone-mediated improvement in insulin sensitivity in individuals with HIV-associated insulin resistance, particularly in the liver.