Background: The long-term efficacy of somatostatin analogues on insulinomas has not been studied.
Design: A prospective study to evaluate the response of octreotide in 21 patients with hypoglycaemia related to endogenous hyperinsulinism who were not treated by surgery.
Results: Reasons for not undergoing surgery were: refusal (n = 3), old age with multiple diseases (n = 5), unlocalized insulinomas (n = 2), malignant unresectable insulinomas (n = 5), multiple insulinomas (n = 3) and diffuse beta-cell disease (n = 3). Hypoglycaemia was responsive to octreotide in 14 of the 21 patients. A short 100-microg octreotide test correctly predicted the efficacy of treatment in six patients with benign insulinomas. Octreoscan scintigraphy was positive in 6 of the 16 patients of whom three were responsive and three unresponsive to octreotide. Octreoscan scintigraphy was negative in 10 of the 16 patients, eight of whom were responsive to octreotide. Subcutaneous octreotide treatment was prolonged for > 6 months (7-144 months, 67 +/- 47 months) in 11 responsive patients. No tachyphylaxis was observed. However, the octreotide dose had to be increased in two patients after 3 and 18 months, respectively. Only one patient suffered from symptomatic biliary lithiasis after 3 years of treatment.
Conclusion: Long-term octreotide treatment can be used to control hypoglycaemia in patients with endogenous hyperinsulinism who are not eligible for surgery; octreotide efficacy on hypoglycaemia could be predicted by a short 100 microg-octreotide test in patients with benign insulinomas, but was not correctly predicted by Octreoscan scintigraphy.