Glucose Metabolism and Visceral Fat in GH Deficient Adults: Two Years of GH-Replacement

The aim of this study was to evaluate the effect of 24 months of growth hormone (GH) replacement on glucose metabolism and visceral fat in 17 adults with GH deficiency: 9 men and 8 women; age 40 +/- 1.8 yr. [range 20-61] and body mass index 25 +/- 0.8 Kg/m2. Glucose metabolism was evaluated by a standard oral glucose tolerance test (OGTT), by the homeostatic model assessment (HOMA) insulin resistance index and by the insulin sensitivity index (ISI)-composite derived from the OGTT. Visceral fat was evaluated by CT scan.Twenty-four months of GH replacement induced an increase in the prevalence of abnormal glucose tolerance, with significant progressive increment in 2h-OGTT insulin levels at 3, 12 and 24 months (p = 0.005). Plasma glucose levels and ISI-composite did not alter during the study. HOMA-IR index increased only in the group of patients (n = 8) who had abnormal OGTT at 24 months (p = 0.012). Visceral fat reduced at month 12 and remained decreased until the end of the study (p = 0.009). In conclusion, the present study suggests that adults with GH deficiency after twenty-four months of GH replacement developed abnormal glucose tolerance, probably due to an increase in insulin resistance, associated with higher insulin levels, despite favorable alterations in body composition.