Myocardial Insulin-mediated Glucose Uptake and Left Ventricular Geometry

Abstract

Whole-body insulin sensitivity has been shown to be impaired in subjects with increased left ventricular relative wall thickness (RWT) and in hypertensive subjects with left ventricular hypertrophy, but the relation between myocardial insulin sensitivity and RWT or left ventricular mass index (LVMI) in normotension is not known. We measured myocardial and skeletal muscle glucose uptake with [18F]fluorodeoxyglucose and positron emission tomography during hyperinsulinemic euglycemic clamp in nine men with wide ranges of echocardiographic RWT and LVMI. The subjects were male, 72-74 years old, normotensive and free from medication or history of heart disease. RWT correlated inversely with skeletal muscle glucose uptake ( r =-0.69, p = 0.04), borderline significantly directly with myocardial glucose uptake (r = 0.62, p = 0.07), and directly with the ratio between myocardial and skeletal muscle glucose uptake (r = 0.77, p = 0.02) during hyperinsulinemic euglycemic clamp. LVMI was not related to insulin-mediated myocardial or skeletal muscle glucose uptake or the ratio between myocardial and skeletal muscle glucose uptake. In conclusion, RWT was inversely related to insulin sensitivity in skeletal muscle and borderline significantly directly related to insulin sensitivity in the myocardium in healthy normotensive elderly men, whereas LVMI was not related to myocardial or skeletal muscle insulin sensitivity.