Effects of long-acting release octreotide on glucose homeostasis in acromegaly patients after trans-sphenoidal surgery.

The present study was aimed to investigate glucose homeostasis and insulin secretion in acromegalic patients during octreotide-long acting release (LAR) therapy and designed as an observational prospective study. 18 acromegalic patients who had undergone trans-sphenoidal surgery with active disease were included. All patients were treated with octreotide-LAR injection for 1 year. These patients received oral glucose tolerance test (OGTT) before, 21 days after, and 1 year after octreotide-LAR treatment. Primary outcomes were changes in glucose levels and insulin secretion during an OGTT. We also determined the differences between subjects with normalized and uncontrolled IGF-1 levels. Of the 18 patients treated with octreotide-LAR for 1 year, 89% achieved fasting GH levels <2.5μg/l, 85% reached the nadir GH concentration < 1 μg/l, and 61 % achieved normal age- and sex-matched IGF-1 values. 21 days after one dose of octreotide-LAR injection, insulin response during OGTT significantly decreased, and the Matsuda index increased significantly. One year after octreotide-LAR therapy, most parameters of glucose homeostasis returned to baseline levels. However, insulin response during OGTT at 30 and 60 min, and the insulinogenic index were still significantly decreased. Compared with the IGF-1-normalized group, the IGF-1 uncontrolled group had the same fasting GH and nadir GH levels and a higher insulin AUC and total insulin secretion. During octreotide-LAR treatment, the early-phase insulin response to OGTT is reduced and plasma glucose levels remained normal in most patients. The IGF-1 uncontrolled group had the same fasting GH and nadir GH levels during OGTT, but had better glucose homeostasis.