PIRENZEPINE DECREASES BASAL AND STIMULATED GH SECRETION IN PATIENTS WITH TYPE-2 (NON-INSULIN-DEPENDENT) DIABETES-MELLITUS

Growth hormone (GH) hypersecretion has been described in diabetes mell itus and seems to be involved in the pathogenesis of diabetes complica tions. As pirenzepine (PZ), a cholinergic muscarinic antagonist, is ab le to inhibit GH hypersecretion in insulin-dependent diabetes mellitus (IDDM), we investigated whether PZ is also able to inhibit spontaneou s and stimulated GH-release in non-insulin-dependent diabetes mellitus (NIDDM). Ten non-obese well-controlled patients with NIDDM underwent in random order the following three double-blind one week treatments: placebo (PL), PZ at low dose (PL in the morning plus PZ 50 mg at 22 h) or high dose (PZ 50 mg at 8 h plus 100 mg at 22 h). Pirenzepine admin istration significantly (p<0.05) decreased nocturnal GH release after both low and high dose (AUC, PL vs PZ: 107.3 +/- 26.5 vs 48.3 +/- 10.5 and 57.6 +/- 9.6 mug/L/h, respectively). The GH response to arginine infusion was significantly inhibited by PZ at high dose (AUC, 147.1 +/ - 48.8 vs 444.7 +/- 194.3 mug/L/h, p<0.01), but not at low dose. Gluco se, insulin, glucagon and somatostatin responses to arginine infusion were not changed by pirenzepine treatment. In conclusion, the muscarin ic blockade by PZ is able to inhibit the spontaneous and stimulated GH secretion also in NIDDM without affecting insulin secretion.