Long-term effects of growth hormone therapy on intermediary metabolism and insulin sensitivity in hypopituitary adults.

Experience with growth hormone (GH) therapy in adult hypopituitarism has been gained for more than 10 years. Most of the data on GH therapy derive from studies with a duration of 2 years or less, but longer term information is required if patients are to be treated with GH replacement therapy for many years. We have studied patients after 4 years of treatment. At the end of this time, body mass index was unchanged but short-term benefits in body composition (decreased percentage body fat and increased fat-free mass) which had been evident at 2 years were still apparent. Fasting plasma glucose and the plasma glucose area under the curve during an oral glucose tolerance test were similar before and after 4 years of therapy, although fasting insulin levels were increased in comparison with baseline. Total cholesterol and low density lipoprotein cholesterol concentrations were lower at 4 years than at the outset but high density lipoprotein cholesterol and triglyceride levels were unchanged. The available evidence therefore suggests that concerns regarding glucose intolerance in patients receiving long-term GH therapy have not been substantiated. The beneficial effects on body composition, and on total and low density lipoprotein cholesterol levels, persisted over the 4 years of study.