Glucose homeostasis in abdominal obesity: hepatic hyperresponsiveness to growth hormone action

Abstract

It has been suggested that (abdominally) obese individuals are hypersensitive to growth hormone (GH) action. Because GH affects glucose metabolism, this may impact glucose homeostasis in abdominal obesity. Therefore, we studied the effect of GH on glucose metabolism in abdominally obese (OB) and normal-weight (NW) premenopausal women. A 1-h intravenous infusion of GH or placebo was randomly administered to six NW [body mass index (BMI) 21.1 ± 1.9 kg/m2] and six OB (BMI 35.5 ± 1.5 kg/m2) women in a crossover design. Insulin, glucagon, and GH secretion were suppressed by concomitant infusion of somatostatin. Glucose kinetics were measured using a 10-h infusion of [6,6-2H2]glucose. In both groups, similar physiological GH peaks were reached by infusion of GH. GH strongly stimulated endogenous glucose production (EGP) in both groups. The percent increase was significantly greater in OB than in NW women (29.8 ± 11.3 vs. 13.3 ± 7.4%, P = 0.014). Accordingly, GH responsiveness, defined as the maximum response of EGP per unit GH, was increased in OB vs. NW subjects (6.0 ± 2.1 vs. 2.2 ± 1.5 μmol·min−1·mU−1·l−1, P = 0.006). These results suggest that the liver is hyperresponsive to GH action in abdominally obese women. The role of the somatotropic ensemble in the control of glucose homeostasis in abdominal obesity is discussed.