The Effect of Metformin Treatment on Disease Control in Patients with Acromegaly

Background: The increase in portal insulin levels has been shown to upregulate growth hormone receptor expression in the liver, leading to increased insulin-like growth hormone- 1 levels. Metformin inhibits hepatic gluconeogenesis and reduces fasting insulin. Objectives: We evaluated the effect of metformin treatment in patients with acromegaly on growth hormone, insulin-like growth hormone-1, and pituitary adenoma size. Methods: Patients who were followed up with the diagnosis of acromegaly in Istanbul University- CerrahpaŦ#159;a, CerrahpaŦ#159;a Medical Faculty were evaluated. The patients were divided into three groups after pituitary adenectomy as those who received somatostatin receptor ligand and metformin treatment (group A), somatostatin receptor ligand treatment only (group B), and those who received metformin treatment only (group C). Groups A and B were compared with each other, and patients in group C were compared among themselves. Results: While the median insulin-like growth factor-1 level decreased to 170 ng/ml in Group A after the treatment, the median insulin-like growth factor-1 level decreased to 229 ng/ml in Group B, and a statistically significant difference was found between the two groups (p =0.020). There was no significant difference in post-treatment growth hormone levels and residual adenoma sizes between groups A and B (p >0.005). In group C, there was no significant difference in growth hormone values pre-and post-metformin treatment (p =0.078); however, the median insulin-like growth factor-1 level decreased from 205 ng/ml to 168 ng/ml during metformin treatment and was found to be statistically significant (p =0.027). Conclusion: Due to the effect of metformin treatment on insulin-like growth factor-1 values in patients with acromegaly, it can be used in disease control, as well as diabetes treatment.