Impact of Somatostatin Analogs Versus Surgery on Glucose Metabolism in Acromegaly: Results of a 5-Year Observational, Open, Prospective Study

Objective: The aim of the study was to investigate the 5-yr impact of surgery and somatostatin analogs (SSA) on glucose metabolism in acromegaly. Design: We conducted an observational, prospective, comparative, nonrandomized study. Patients: The 100 patients (48 women, 52 men; median age, 49 yr) in the study were grouped as follows for treatment: SSA only (group A; n = 34); SSA followed by surgery (group B; n = 20); surgery only (group C; n = 30); and surgery followed by SSA (group D; n = 16). Results: At diagnosis, 28% had impaired glucose tolerance, and 22% had diabetes mellitus; fasting glucose levels (4.13–10.60 mmol/liter) were best predicted by age (t = 2.88; P = 0.0049) and disease duration (t = 1.99; P = 0.049). After 60 months, fasting glucose levels reduced (−4.9 ± 19.7%) in group A only, whereas they did not change in the other groups. In the 68 nondiabetic patients at baseline, fasting glucose levels increased by 0.7 ± 11.2%, 7.5 ± 10.3%, 4.3 ± 10.4%, and 4.3 ± 14.8% (P = 0.28), from groups A to D, respectively. Percentage change of fasting glucose in all patients receiving SSA was 1.9 ± 12.3%, and in those not receiving SSA it was 6.4 ± 10.8% (P = 0.13). Overall, prevalence of new onset of diabetes during SSA treatment was nine of 55 (16.4%) vs. three of 23 after surgery (13.0%, P = 0.98). Deterioration of glucose tolerance was correlated with increased body mass index (r = 0.49, P < 0.0001) and not with use of SSA or surgery (r = 0.06; P = 0.53), control or not of GH (r = −0.10, P = 0.31) and IGF-I (r = −0.12; P = 0.22). Conclusions: The results of this study demonstrate a similar deterioration of glucose tolerance after 60 months in patients receiving SSA or cured with surgery. Increase in body mass index was the major predictor of deterioration of glucose tolerance. This 5-year, observational, prospective study demonstrates that deterioration of glucose tolerance occurs in a similar proportion of patients controlled with surgery and somatostatin analogues or cured with surgery. Body mass index increase was found to be the major predictor of deterioration of glucose tolerance.