Pasireotide (SOM230) is a somatostatin analog with affinity for somatostatin receptor subtypes sst_1–3 and sst₅. Clinical trials have demonstrated the efficacy of pasireotide in treating Cushing's disease and acromegaly but have also shown adverse effects on glucose metabolism.

The aim of the study was to evaluate the mechanism of pasireotide-associated hyperglycemia.

We conducted a randomized, single-center, open-label study.

Forty-five healthy male volunteers were randomized to pasireotide 600 (n = 19), 900 (n = 19), or 1200 μg (n = 7) sc twice a day for 7 days. Randomization to 1200 μg was discontinued because of increased severity of gastrointestinal adverse events in this arm. An oral glucose tolerance test (OGTT), a hyperglycemic clamp test, and a hyperinsulinemic-euglycemic clamp test were performed on 3 consecutive days at baseline and treatment end.

The effect of pasireotide on insulin secretion and hepatic/peripheral insulin sensitivity was measured. The secondary objective was to evaluate the effects of pasireotide on oral glucose absorption.

Pasireotide treatment resulted in significant decreases in insulin AUC_{0–180 min} during both the hyperglycemic clamp test (−77.5%; P < .001 in both dose groups) and the OGTT (−61.9%; P < .001 in both dose groups). Suppression of glucagon levels was less pronounced. No significant changes in hepatic or peripheral insulin sensitivity were found during the hyperinsulinemic-euglycemic clamp test. Additionally, significant increases in glucose AUC_{0–180 min} (+67.4%) and decreases in AUC_{0–180 min} glucagon-like peptide-1 (−46.7%) and glucose-dependent insulinotropic polypeptide levels (−69.8%) were observed during the OGTT. No dose dependency or unexpected adverse events were observed.

Pasireotide-associated hyperglycemia is related to decreases in insulin secretion and incretin hormone responses, without changes in hepatic/peripheral insulin sensitivity.