Sex Steroids Affect Triglyceride Handling, Glucose-Dependent Insulinotropic Polypeptide, and Insulin Sensitivity

Abstract

OBJECTIVE— To evaluate metabolic effects of sex steroids in nonfasting and fasting condi- tions, independent from changes in body composition. RESEARCHDESIGNANDMETHODS— A randomized clinical trial was performed to create contrasting sex steroid levels in healthy young men: by letrozole (aromatase inhibitor) to lower estradiol (E2 ) and increase testosterone (group T, n?10) versus letrozole plus E2 patches to lowerTand raiseE2 (group E, n?10). Mixed meals and hyperinsulinemic-euglycemic clamps were performed before and after a 1-week treatment period. RESULTS— Following intervention, the postprandial triglyceride response displayed a di- verging response with a decline in group T and an increase in group E; the postprandial glucose- dependent insulinotropic polypeptide (GIP) response increased in group T. Insulin sensitivity increased in group T but remained unaltered in group E. CONCLUSIONS— In healthy young men, short-term changes in sex steroids affect post- prandial triglyceride and GIP response and insulin sensitivity.