BLUNTED GH RESPONSE TO GROWTH HORMONE-RELEASING HORMONE (GHRH) ALONE OR COMBINED WITH ARGININE IN NON-INSULIN-DEPENDENT DIABETES-MELLITUS

An increased spontaneous and stimulated growth hormone (GH) secretion is well documented in insulin-dependent diabetes mellitus. On the cont rary, in non-insulin-dependent diabetes mellitus (NIDDM) conflicting r esults arise from literature. In 14 patients with NIDDM, 7 normal weig ht (NWD) and 7 obese (OD), we investigated the somatotrope responsiven ess to GHRH (1 mu g/kg) alone or combined with arginine (ARC, 0.5 g/kg ), which is able to enhance the GH response to GHRH, probably by inhib iting somatostatin release from hypothalamus. Baseline ICF-I, IRI, FFA and glucose levels were also determined. Twelve healthy normal subjec ts (NS) and 12 obese patients (OP) were evaluated as control groups. G H but not IGF-I levels were higher (p<0.05) in NS than in OP (1.5+/-0. 5 vs 0.5+/-0.2 mu g/l). Insulin levels were higher (p<0.05) in OP than in NS, NWD and OD (18.7+/-1.8 vs 8.7+/-0.5, 6.4+/-1.9 and 11.8+/-1.2 mu U/l). FFA were higher (p<0.05) in NWD, OD and OP than in NS (0.69+/ -0.04, 0.70+/-0.04 and 0.65+/-0.06 vs 0.39+/-0.03 mmol/l). Plasma gluc ose was higher (p<0.05) in diabetic patients than in normal and obese subjects. CH responses to GHRH in NWD, OD and OP were similar (AUG: 22 1.6+/-33.3, 206.0+/-35.9 and 177.2+/-57.3 mu g/I/min, respectively) an d all lower (p<0.05) than that in NS (776.7+/-206.5 mu g/l/min). ARG d etermined a significant increase of GHRH-induced GH release in all gro ups (p<0.01). Again the GH responses to ARC + GHRH in NWD, OD and OP w ere lower (p<0.05) than that observed in NS. In conclusion, our result s demonstrate that, irrespective of body weight, patients with non-ins ulin-dependent diabetes mellitus had an impairment of CH responses to GHRH alone or combined with arginine. This finding may be explained by the presence of high FFA levels which are known to inhibit GH secreti on.