Effect of a new long-acting somatostatin analogue (SMS 201-995) on glycemic and hormonal response to a mixed meal in acromegalic patients

We investigated in 6 acromegalic patients the acute effects on glucose tolerance and insulin secretion of a single sc injection of the somatostatin analogue SMS 201-995, performed 4 h before a mixed meal with xylose administration. Growth hormone levels decreased from 34.0 +/- 20.3 (mean +/- SE) to a minimum of 9.3 +/- 3.0 ng/ml, 3 1/2 h after the injection. A significant inhibition of insulin secretion was also noticed, with a fall from 25.3 +/- 6.4 to 6.3 +/- 2.3 microU/ml at 1 h, and a lower and delayed peak level after the mixed meal. However, the postprandial plasma glucose increase was not different from a control day, while plasma xylose levels were lower. Mean glucagon level after SMS 201-995 was lower than control value in 3 out of the 4 patients in whom it was determined. The decrease of serum growth hormone levels, together with partial glucagon inhibition and, more important, a slowing of intestinal absorptive processes, counterbalanced the inhibitory action of SMS 201-995 on insulin secretion, and no deterioration in carbohydrate tolerance could be demonstrated. However, before SMS 201-995 is employed in the management of acromegalic patients refractory to surgery and bromocriptine therapy, we need further observations of postprandial glycemic profiles during long-term therapy with multiple daily injections of the compound.