Changes in insulin levels following 6-month treatment with recombinant human growth hormone in growth hormone-deficient adults

Introduction: Eighty-six adult patients with GH deficiency (GHD) of adult or childhood onset were treated for 6 months, with recombinant human growth hormone (r-hGH) at a low (LD) or conventional dose (CD). The treatment effect on insulin levels was investigated. Methods: This manuscript refers to the Italian addendum to an International Study (B9R-EW-GDED) in which patients with GHD were randomized to receive r-hGH replacement therapy at a dose of either 3 μg/kg/day or 6 μg/kg/day for the 3 months. The dose was then doubled for the next 3 months. Results: After 6 months of r-hGH treatment, insulin levels increased with both GH dosages, with a greater increase achieved in the low-dose subgroup. Insulin levels also increased significantly in the childhood-onset, while even decreased in the adult-onset subgroup. On the whole, in more than 50% of patients, insulin values rose by >13%. Moreover, mean levels of IGF-I increased 2–3 fold (p<0.001 vs baseline) in both the LD and CD groups. Significant and similar increases in IGF binding protein-3 levels were seen in both the LD and CD groups over the treatment period, regardless the time of onset of GHD. Conclusion: Insulin increased with both GH dosages and more than half of patients presented an important increase in insulin plasma levels. It would be of interest to assess if there is a correlation between the changes in insulin levels and other cardiovascular risk factors such as hemostatic parameters.