A Comparative Study of Olmesartan and Valsartan on Insulin Sensitivity in Hypertensive Patients with Diabetes Mellitus or Impaired Glucose Tolerance (OVIS Study)

Activation of renin angiotensin system is implicated in insulin resistance. In mega trials, it has been suggested that angiotensin receptor blockers may be beneficial on insulin sensitivity in hypertensive patients. We conducted a multicenter, open-label, parallel-group trial to compare the effects of olmesartan and valsartan on insulin sensitivity and adiponectin levels in 206 hypertensive patients with diabetes mellitus or impaired glucose tolerance. Patients were randomly assigned to either olmesartan 20 mg/day or valsartan 80 mg/day treatment for 24 weeks. Blood pressure, fasting glucose, fasting insulin, glycosylated hemoglobin (HbA1c), homeostasis model assessment for insulin resistance (HOMA-IR), and serum adiponectin levels were measured. The efficacy was evaluated in 197 patients (olmesartan, n=98; valsartan, n=99). At baseline, all parameters except for systolic blood pressure (SBP) and serum triglyceride did not differ between the 2 groups. HbA1c decreased slightly after a 24-week treatment with valsartan, but not olmesartan, while the decrease did not significantly differ in the two groups. There was no difference in the change from the baseline between olmesartan and valsartan groups concerning fasting glucose, fasting insulin, HOMA-IR, and adiponectin levels after 24-week treatment. The decrease in SBP tended to be greater in the olmesartan group than in the valsartan group even with adjustment for the baseline difference. In conclusion, there was no significant difference in insulin sensitivity or adiponectin levels between the olmesartan and valsartan groups. In the standard dose, olmesartan significantly decreased SBP as compared with valsartan.