Effect of losartan and amlodipine on insulin sensitivity in non-diabetic hypertensive patients

Background: Hypertensive patients show higher insulin levels than normotensive controls. Hypertension is linked to impaired glucose tolerance and resistance to the action of insulin. Untreated hypertensive patients are at risk of developing new onset diabetes mellitus. Different antihypertensive drugs affect the insulin sensitivity distinctly. Few studies have demonstrated the beneficial effects of losartan, an angiotensin receptor blocker on the glucose insulin metabolism, but other studies have failed to demonstrate the insulin resistance lowering effect of losartan. Amlodipine, a long acting calcium channel blocker is considered to have neutral effects on the glucose-insulin metabolism.Methods: In a prospective, open-label, parallel group study, non-diabetic patients with mild to moderate hypertension were randomized to either losartan (titrated from 50 to 100 mg /day, n=20) or amlodipine (titrated from 5 to 10 mg/ day, n=20) for period of 24 weeks. At baseline, 12 weeks and 24 weeks fasting plasma glucose, fasting plasma insulin, homeostasis model assessment for insulin resistance (HOMA-IR) apart from lipid parameters, mean systolic and diastolic blood pressures levels were determined.Results: Intragroup comparison shows that both losartan and amlodipine significantly reduced the HOMA-IR index (P < 0.05, 24 weeks vs. baseline). Losartan reduced HOMA-IR more than amlodipine but this reduction was not statistically significant.Conclusions: Losartan and amlodipine lowered insulin resistance in patients of mild to moderate hypertension.