Glucose metabolism in adults with growth hormone deficiency

Adults with GHD have normal overnight fasting glucose levels and normal overall glucose turnover. In the absence of GH, insulin secretion is reduced and may be associated with impaired glucose tolerance. The lack of GH is associated with normal insulin sensitivity but reduced hypoglycaemic responsiveness, probably due to a reduced supply of gluconeogenic substrates. When GHD is associated with obesity, however, hyperinsulinaemia and insulin resistance ensue and hypoglycaemic responsiveness is restored. In adults with GHD, treatment with recombinant human GH for 6 months increased fasting plasma glucose to within the normal range, with no change in overall glucose turnover and carbohydrate tolerance, in the presence of elevated basal insulin levels.