Blockade of the renin-angiotensin system increases adiponectin concentrations in patients with essential hypertension

Adiponectin, an adipocyte-derived protein, has been suggested to play an important role in insulin sensitivity. We examined the association between insulin sensitivity (M value) evaluated by the euglycemic-hyperinsulinemic glucose clamp and adiponectin concentrations in 30 essential hypertensives (EHT) and 20 normotensives (NT) and investigated the effect of blockade of the renin-angiotensin system (RAS) on adiponectin concentrations. EHT were divided into 12 insulin-resistant EHT (EHT-R) and 18 non-insulin-resistant EHT (EHT-N) using mean-1 SD of the M value in NT. There were no intergroup differences in age, gender, and body mass index (BMI). EHT-R had significantly higher levels of insulin and triglyceride and lower levels of adiponectin than did NT and EHT-N. EHT-R had higher levels of free fatty acid and lower levels of high-density lipoprotein (HDL) cholesterol than did EHT-N. Adiponectin concentrations were positively correlated with M value and HDL cholesterol and negatively correlated with BMI, insulin, free fatty acid, and triglyceride but not with blood pressure. M value, BMI, and HDL cholesterol were independent determinants of adiponectin concentrations in multiple and stepwise regression analyses. Sixteen EHT were treated with an angiotensin-converting enzyme inhibitor (temocapril, 4 mg/d; n=9) or an angiotensin II receptor blocker (candesartan, 8 mg/d; n=7) for 2 weeks. Treatment with temocapril or candesartan significantly decreased blood pressure and increased M value and adiponectin concentrations but did not affect BMI and HDL cholesterol. These results suggest that hypoadiponectinemia is related to insulin resistance in essential hypertension and that RAS blockade increases adiponectin concentrations with improvement in insulin sensitivity.