Context: Impaired glucose tolerance and diabetes mellitus are frequently present in acromegalic patients in whom the degree of impaired glucose metabolism seems directly correlated with GH levels. Microalbuminuria is reported to be directly correlated with insulin resistance and both conditions predict cardiovascular disease mortality.

Objective: To investigate the microalbuminuria levels, as marker of endothelial dysfunction.

Design: Observational, multicenter, open prospective.

Subjects: 74 patients with active acromegaly [52 with normal glucose tolerance (NT), 16 impaired glucose tolerance (IGT) and 6 were diabetic (DM)] and 50 healthy subjects, matched for age, gender and BMI, studied as controls.

Results: In the whole group, mean GH and IGF-I levels were 24.2 ± 3.9 ng/ml and 700.1 ± 23.0 µg/L, respectively. The Insulin Sensitivity Index (ISI) in the patients was lower than in the controls (P < 0.0005). In IGT and DM patients microalbuminuria was higher than in NT patients (P < 0.05, P < 0.0005 respectively). Hypertensive patients had higher levels of microalbuminuria than normotensive ones (P < 0.005). The levels of microalbuminuria related to creatinine were directly correlated with fasting glucose levels (r = 0.27; P = 0.0019), fasting insulin levels (r = 0.28; P = 0.017) and insulin after 90 (r = 0.26; P = 0.027) and 120 min post glucose load (r = 0.26; P = 0.023) and indirectly correlated with ISI composite (P < 0.0001, r = -0.48). By a multivariate analysis, the log-ISI composite was the strongest predictor of microalbuminuria (t = -3.19; P = 0.0021).

Conclusions: Impairment of glucose tolerance in acromegaly is associated with high levels of microalbuminuria for this reason microalbuminuria should be part of cardiovascular risk assessment in these patients.