Insulin sensitivity in normotensive subjects during angiotensin converting enzyme inhibition with fosinopril.

The effect of the new ACE-inhibitor, fosinopril, on insulin sensitivity (SI), glucose homoeostasis and lipid profile has been examined in 24 young, healthy, normotensive men. SI, fasting plasma glucose and insulin, serum total triglycerides (Tg) and lipoprotein cholesterol (C) fractions, and ACE activity were assessed after subjects had taken placebo for 1 week and after 3 further weeks either on placebo (12 subjects) or fosinopril 20 mg daily (12 subjects), administered in a double-blind, randomized order. Measurements were made after 3 days on a standard diet (2500 kcal/d, 45% carbohydrates, 40% fat and 15% proteins) and after an overnight fast. Compared with control values at the end of the run-in placebo phase, fosinopril reduced plasma ACE activity (from 106 to 24 nmol.ml-1.min-1), Significantly increased plasma potassium and lowered upright systolic blood pressure. It also improved the k-value of the glucose disappearance rate after glucose load (from -1.70 to -1.88%.min-1) and tended to increase SI slightly although not significantly (from 10.2 to 12.0.10(-4).min-1.microU-1.ml-1). Fasting plasma glucose, insulin, serum total, high-, low-, and very-low density lipoprotein cholesterol fractions and total triglycerides were unchanged following fosinopril and placebo. The findings indicate that in healthy lean humans, ACE inhibition with fosinopril is neutral with regard to lipoprotein and carbohydrate metabolism, and that it may slightly enhance cellular glucose disposal. This calls for further evaluation in individuals at high risk of developing insulin resistance and in patients with impaired insulin sensitivity related to hypertension, obesity, decreased glucose tolerance and diabetes mellitus.