Effects of growth hormone on insulin resistance and atherosclerotic risk factors in obese type 2 diabetic patients with poor glycaemic control

Abstract

OBJECTIVE: We aimed to evaluate the combined effects of GH treatment and diet restriction on lipolysis and anabolism, insulin resistance and atherosclerotic risk factors in obese patients with type 2 diabetes mellitus (T2DM). SUBJECTS: This randomized, double-blind, placebo-controlled study included 24 obese T2DM patients (male : female = 12 : 12, mean age 53.7 +/- 7.2 years) with poor glycaemic control (fasting plasma glucose 10.673 +/- 1.121 mmol/l, HbA(1C) 9.9 +/- 2.3%). Sixteen of these patients were treated with recombinant human GH (1-1.5 units/day, 5 days/week) while undergoing diet restriction and exercise for 12 weeks. METHODS: Anthropometric and bioelectrical impedance measurements were undertaken to determine the lean body mass and total body fat. Computed tomography (CT) was performed to estimate visceral and subcutaneous fat distribution at the umbilicus level and the muscle area of the midthigh. Insulin resistance was measured by the insulin tolerance test (ITT) and by the homeostasis model assessment of insulin resistance (HOMA-IR). RESULTS: The ratios VSR (visceral fat area/subcutaneous fat area) and VMR (visceral fat area/thigh muscle area) were significantly decreased in the GH-treated group compared to the control group. An increase in lean body mass was observed in the GH-treated group. Levels of total cholesterol, triglyceride, free fatty acid (FFA), fibrinogen, and plasminogen activator inhibitor-1 (PAI-1) were significantly decreased after GH treatment. Fasting glucose levels decreased similarly (P < 0.05 anova) in both groups during the treatment period. Fasting C-peptide levels significantly increased, whereas insulin levels significantly decreased, in the GH-treated group, but no changes were observed in the control group. The insulin sensitivity index (ISI) was significantly increased in the GH-treated group (1.3 +/- 1.4 vs. 1.9 +/- 1.0%/min, P < 0.05). CONCLUSIONS: GH treatment in obese T2DM patients with poor glycaemic control is beneficial in decreasing the amount of visceral fats, and may therefore result in improvements in insulin resistance, atherosclerotic risk factors and dyslipidaemia.