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. OBJECTIVE: 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- Cerrahpasa, Cerrahpasa 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.

Patients with acromegaly might not be at higher risk for dopamine agonist-induced impulse control disorders than those with prolactinomas.

OBJECTIVE: To evaluate the prevalence of impulse control disorders (ICD) and psychiatric symptoms in patients with acromegaly receiving dopamine agonists (DA) in comparison with those with prolactinoma, nonfunctioning pituitary adenomas (NFA), and healthy controls (HC). DESIGN: Forty patients with acromegaly, 40 with prolactinoma, 38 with NFA, and 32 HCs were included. All patients and controls were evaluated using the revised version of the Minnesota Impulsive Disorders Interview (MIDI-R), Symptom Check List (SCL-90-R) questionnaire, Barratt Impulsiveness Scale (BIS-11), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI). RESULTS: We detected ICD associated with DAs in two patients with acromegaly (5%) and three patients (7.5%) with prolactinoma. All patients' symptoms resolved after discontinuation of the drug. While the mean DA dose was higher in patients with acromegaly than prolactinomas (p < 0.05), no difference was detected in terms of ICD prevalence between two groups (p > 0.05). SCL-90 depression and interpersonal sensitivity subscale positivity was higher in patients with NFA than HCs. Patients with prolactinoma had higher obsession and interpersonal sensitivity positivity and those with NFA had higher somatization, interpersonal sensitivity, and depression positivity as compared to patients with acromegaly (p < 0.05 for all). CONCLUSIONS: Although DA dose was significantly higher in patients with acromegaly, there was no significant difference in the prevalence of DA-related ICD. The higher prevalence of positive screening in SCL-90 in patients with NFA in comparison to HCs supports the hypothesis that the presence of a pituitary adenoma per se might cause significant psychiatric symptoms.