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.