Glucose homeostasis in patients with acromegaly treated with surgery or somatostatin analogues

Objective Long-acting somatostatin analogues (SSA) are widely used for the treatment of acromegaly; however, they also alter beta-cell function by inhibiting insulin secretion. In this study, we assess the effect of SSA on glucose homeostasis in patients with acromegaly treated with SSAs, compared to patients treated with surgery. Design We studied four groups of patients with acromegaly: at the time of diagnosis (group I, n = 53), after successful transsphenoidal surgery (TSS, group II, n = 30) and under successful SSA treatment (group III, n = 20); 22 patients were studied only before treatment, 19 only post-treatment, while 31 patients (group IV) were studied before and after the treatment. Measurements Patients underwent an oral glucose tolerance test. Insulin sensitivity and beta-cell insulin secretion were estimated using appropriate mathematical models. Results Control of acromegaly with either TSS or SSA improved insulin sensitivity as evident by significantly lower fasting and post-glucose insulin levels and HOMA-IR. In addition, patients of group III compared to patients of group II demonstrated significantly lower HOMA-beta% (52.5 +/- 10.9 vs 189.6 +/- 86.7, P < 0 05) and lower first and second phase insulin release (443 +/- 83.5 vs 1077 +/- 140.8, P < 0.05 and 150 +/- 18.2 vs 285 +/- 33.3, P < 0.05), respectively. Also, lower fasting glucose levels and a lower prevalence of diabetes were noted in group II compared to group III (5.1 +/- 0.2 vs 6.2 +/- 0.2 mM, P < 0.05, and 13.3% vs 40%, P < 0.0031, respectively). Conclusions Control of acromegaly with SSA seems to exhibit a negative effect on pancreatic b-cell function. Whether this has long-term clinical implications remains to be established. Nevertheless, careful monitoring of glucose metabolism in patients under SSA is beneficial for their optimal management.