Effect of growth hormone releasing hormone on growth hormone, prostaglandin E2 and insulin in non-insulin-dependent diabetic patients.

In a previous paper we demonstrated a link between growth hormone releasing hormone (GHRH) and prostaglandin E2 (PGE2) in their action on growth hormone (GH) in normal subjects. However, in diabetes mellitus various disturbances of GH and PGE2 secretion have been reported. In the present study the response of GH, PGE2 and insulin to GHRH (1 microgram/kg b.w.) intravenously was investigated in 12 poorly controlled non-insulin-dependent diabetic patients (8 males and 4 females) and 10 normal volunteers (5 males and 5 females). After GHRH injection, GH increased in diabetic patients from 2.28 +/- 0.52 mU/l to 14.76 +/- 1.29 mU/l at 30 min (p < 0.001). This response was not statistically different compared to the control subjects. The basal values of plasma PGE2 were significantly lower in diabetic patients than in control subjects. GHRH induced a slight but significant increase of PGE2 in normal subjects (9.80 +/- 0.44 pg/ml at 0 min; 14.50 +/- 1.30 pg/ml at 90 min, p < 0.05) and did not have any effect on PGE2 in diabetic patients. Serum insulin decreased significantly after GHRH in both normal subjects and diabetic patients at 60 min. We conclude that GH response to GHRH is not significantly impaired in poorly controlled non-insulin-dependent diabetic patients. The lack of an effect of GHRH on PGE2 in diabetic subjects provides further evidence of abnormal PGE2 synthesis or metabolism in this disorder. The physiological significance of the GHRH suppressive effect on serum insulin remains to be explained.