Growth hormone and sex steroid effects on serum glucose, insulin, and lipid concentrations in healthy older women and men.

CONTEXT With aging, GH, IGF-I, and sex steroid concentrations and glucose tolerance decrease, and body fat and serum lipids increase. OBJECTIVE The aim of the study was to assess GH and/or sex steroid administration effects on serum glucose, insulin, insulin sensitivity, and lipids in older individuals. DESIGN A double-masked, 2 x 2 factorial, placebo-controlled, double-dummy design was used for the study. INTERVENTION GH and/or sex steroid [transdermal estradiol plus oral medroxyprogesterone acetate in women (HRT); testosterone enanthate (T) in men] were administered for 6 months. PARTICIPANTS Healthy, community-dwelling women (n = 57) and men (n = 74) ages 65-88 yr (mean, 72 yr) participated in the study. MAIN OUTCOME MEASURES We measured serum glucose, insulin, and insulin sensitivity [quantitative insulin sensitivity check index (QUICKI) and insulin sensitivity index (ISI)] before and during an oral glucose tolerance test and lipid profiles. RESULTS In women, GH did not alter oral glucose tolerance test 120 min or 2-h area under the curve (AUC) glucose values, but it increased 120 min insulin and AUC insulin. There were no significant effects of HRT or GH+HRT. ISI and QUICKI decreased after GH. In men, GH increased 120 min and AUC glucose and insulin AUC. GH+T increased 120 min glucose and glucose and insulin AUCs. T alone did not affect glucose or insulin. ISI decreased after GH and GH+T, whereas QUICKI decreased after GH. GH in women and men and GH+T in men decreased QUICKI by 4 wk. In women, HRT decreased total cholesterol and low-density lipoprotein (LDL)-cholesterol, and GH decreased LDL-cholesterol. In men, total cholesterol decreased after T and GH+T. LDL-cholesterol decreased after GH and GH+T. GH increased serum triglycerides. CONCLUSIONS GH administration to healthy older individuals for 6 months increased insulin resistance with moderately beneficial effects on lipids.