GENDER AND INSULIN SENSITIVITY IN THE HEART AND IN SKELETAL-MUSCLES -STUDIES USING POSITRON EMISSION TOMOGRAPHY

Good insulin sensitivity is independently associated with a low risk f or coronary heart disease, but it is unclear whether this risk factor differs between men and women, We compared insulin sensitivity of gluc ose uptake directly in muscle and heart tissues between healthy women (age 29 +/- 2 years, body mass index [BMI] 22 +/- 1 kg/m(2), VO2max 39 +/- 4 ml.kg(-1).min(-1)) and men matched for age (31 +/- 2 years) BMI (23 +/- 1 kg/m(2)), and VO2max (44 +/- 3 ml.kg(-1).min(-1)) using [F- 18]fluoro-2-deoxy-D-glucose and positron emission tomography under hyp erinsulinemic (insulin infusion rate 1 mU.kg(-1).min(-1)) normoglycemi c conditions, Whole body insulin sensitivity was 41% greater in women (52 +/- 6 mu mol.kg body wt(-1).min(-1)) than in men (37 +/- 3 mu mol. kg body wt(-1).min(-1), P < 0.05), This difference was explained by a 47% greater rate of glucose uptake by femoral muscles (113 +/- 10 vs, 77 +/- 7 mu mol.kg muscle(-1).min(-1), women vs, men, P < 0.01), Insul in-stimulated glucose uptake rates in the heart were similar in women (738 +/- 58) and men (749 +/- 62 mu mol.kg muscle(-1).min(-1)), Femora l muscle insulin sensitivity was closely correlated with whole body in sulin sensitivity (r = 0.84, P < 0.001), Gender and VO2max together ex plained 68% of the variation in femoral muscle glucose uptake, We conc lude that women are more sensitive to insulin than equally fit men bec ause of enhanced muscle but not heart insulin sensitivity.