Short-term aromatase inhibition: effects on glucose metabolism and serum leptin levels in young and elderly men

Objective: To assess and compare the effects of short-term aromatase inhibition on glucose metabolism, lipid profile, and adipocytokine levels in young and elderly men. Design and methods: Ten elderly and nine young healthy men were randomized to receive letrozole 2.5 mg daily or placebo for 28 days in a crossover design. Results: Both in young and elderly men, active treatment significantly increased serum testosterone (+128 and +99%, respectively) and decreased estradiol levels (-4.1 and -62%, respectively). Fasting glucose and insulin levels decreased in young men after active intervention (-7 and -37%, respectively) compared with placebo. Leptin levels fell markedly in both age groups (-24 and -25%. respectively), while adiponectin levels were not affected by the intervention. Lipid profile was slightly impaired in both groups, with increasing low density lipoprotein-cholesterol levels (+14'%) in the younger age group and 10% lower levels of APOA1 in the elderly. A decline in IGF1 levels (-15%) was observed in the younger age group. No changes in weight or body mass index were observed in either young or old men. Conclusions: Short-term aromatase inhibition appears to affect glucose metabolism in young men. and lipid metabolism, including leptin secretion, in young and elderly men. Furthermore. the short period of exposure suggests that these changes might be mediated by direct effects of sex steroids rather than by changes in body composition.