Endocrine Abstracts

Background: Insulin resistance leading to glucose intolerance and even diabetes mellitus is common in acromegaly and is partially caused by pathological high concentrations of growth hormone (GH) and somatomedin C (IGF-1). On the other hand, somatostatin analogues, common treatment option, can cause inhibition of insulin secretion and glucose tolerance disturbances.

Aim: Of the study was to determine impact of prolonged somatostatin analogues administration on insulin resistance in acromegaly.

Material: 27 acromegalics 16 women and 11 men, aged 23 to 65, mean 43, previously untreated and with excluded diabetes mellitus was enrolled into this study.

Intervention: Primary octreotide LAR treatment for 6 months prior to neurosurgery.

Methods: Prolonged (0–180’) oral glucose tolerance test (OGTT) with glucose, GH and insulin assessment was performed initially, 2 weeks after first octreotide injection and after 6 months of treatment. Insulin resistance was calculated as fasting glucose to fasting insulin ratio (FG/FI), sum of insulin levels during OGTT (sI). Also, HOMA and Quicki indexes was calculated. Control group consists of healthy volunteers from department database. Disease activity was calculated with clinical symptoms score, GH and IGF-1 levels.

Results: Initially, 21 out of 27 (77%) patients was insulin-resistant (FG/FI<6), HOMA index was significantly higher than in controls (3.2 S.D. 1.4 v. 1.6 S.D. 0.8 P<0.001). After 6 months of treatment insulin-resistance presented 16 (59%), insulin levels drop significantly in fasting state and during OGTT (sI 659 S.D. 160 v. 430 S.D. 180 P<0.05 initially v. 6 months therapy) whereas glucose levels did not differ significantly (P<0.01). HOMA index fall close to controls (2.1 S.D. 0.7), and Quicki was slightly higher than initially (mean 0.329 v. 0.369 respectively), but difference did not reach statistical significance (P=0.12).

Conclusions: Somatostatin analogue therapy could improve insulin-sensitivity and did not worsen glucose metabolism in patients with acromegaly.