Endocrine Abstracts

Introduction: Impaired glucose tolerance and diabetes mellitus are frequently seen complications of acromegaly. Insulin resistance due to chronic growth hormone (GH) excess and inhibition of insulin and glucagon secretion by long-acting somatostatin analogues (SA) used in the treatment are the main reasons of the impaired glucose tolerance.

Objective: To determine the effect of long-acting SA treatment on glucose homeostasis regarding the insulin resistance and pancreatic β-cell function.

Method: Totally 30 patients (17 male, 13 female; mean age:44.63±11.85 years) were enrolled in the study. Serum IGF1 concentrations and glucose, insulin, GH levels at 0, 30, 60 and 120 min during OGTT were measured. Patients were categorized into 3 groups according to their disease activity. Patients cured after operation, patients with active disease after operation but in remission after SA therapy and patients with active disease after operation and SA therapy were defined as cure, remission and active group, respectively. For the interpretation of glucose homeostasis, formulas for insulin resistance (HOMA-IR, QUICKI) and β-cell function (HOMA-β, Insulinogenic index) were used.

Results: There was no statistically significant difference between groups for HOMA-IR and QUICKI (P=0.78; P=0.781) and also between disease activity and insulin resistance. For the insulinogenic index, which was the marker of early phase of insulin secretion, there was a borderline difference in significance between groups (P=0.076). HOMA-β of cure group was higher than the other two groups independent of disease activity. In the cure group, serum insulin levels and peak insulin secretion was higher, time to reach the peak level was shorter than the other groups (P=0.420; P=0.176).

Conclusion: Treatment with long acting SA in acromegaly inhibits insulin secretion from pancreatic β-cells, so causes deterioration in glucose homeostasis. Due to the increase in cardiovascular morbidity and mortality, patients on SA therapy should be routinely followed-up for glucose intolerance.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.