The effect of plasma glucose on the growth hormone response to human pancreatic growth hormone releasing factor in normal subjects.

Pituitary responsiveness to 44 amino acid human pancreatic growth hormone releasing factor was tested under conditions of euglycaemia and hyperglycaemia in six normal subjects. A 100 micrograms dose of growth hormone releasing factor was given at a fasting blood glucose of 5.1 +/- 0.4 mmols/l (mean +/- S.D.), and at a blood glucose level of 10.9 +/- 1.5. Under conditions of hyperglycaemia, the GH response to releasing factor was significantly depressed when compared to results obtained at fasting blood glucose (n = 6, t = 3.902, P = 0.0114). This is in keeping with the hypothesis that hyperglycaemia, mediated by the hypothalamus, causes decreased pituitary sensitivity to natural growth hormone releasing hormone.