Hypothesis: The growth hormone (GH) excess displayed in acromegaly induces insulin resistance up to diabetes mellitus (DM). The somatostatin analogues (as octreotide LAR) are useful in controlling the GH levels but disturbances of glucose metabolism might be seen.
Objective: This study evaluates the acromegalic glycemic profile under octreotide.
Methods & results: Out of the total number of patients (N=34) diagnosed with active acromegaly, only some were followed (N=25; male/ female ratio: 6/ 19; mean age: 51.8 years) by testing GH, IGF1 (Insulin Growth Factor 1), basal glucose and oral glucose tolerance test (OCGTT) at baseline, 6 and 12 months under Octreotide (first 6 months with 20 mg/ 28 days + 6 months with 30 mg/ 28 days). Pre-treatment values were 17.6% of patients had DM, 14.7% - impaired glucose tolerance, 26.5% - impaired fasting glucose, and 41.2% - normal assays. From the statistical point of view, the DM patients were significantly older and had higher GH levels than the acromegalic without glycaemia disturbances. They did not achieve significant changes in basal blood glucose and glycated hemoglobin after 6 months, neither after 12 months. After 6 months, there were no significant changes in basal glycaemia in patients with normal baseline glycaemia but 2-hours OGTT glucose values were significantly lower than initially (82.35 mg/ dl vs. 93 mg/ dl, p=0.005) consistent with reduced levels of GH and IGF1. After 12 months, both basal and 2-hours glucose levels in OGTT were similar to baseline despite the significant lower GH (3.3 vs. 6.61 ng/ mL, p=0.003) and IGF1 (332 vs. 713 ng/ mL, p=0.001).
Conclusions: Octreotide therapy induces an improvement in glycemic profile in patients with active acromegaly without diabetes mellitus consistent with decreased levels of GH and IGF1. In patients with diabetes, partial control of glucose metabolism is due to inadequate suppression of GH and IGF1 after one year of treatment.
Keywords: acromegaly; diabetes mellitus; glycaemia; octreotide.