The impact of sleep apnea treatment on carbohydrate metabolism in patients with acromegaly

Sleep Apnea is highly prevalent and may contribute to insulin resistance in patients with acromegaly. The primary aim of this study was to assess the impact of sleep apnea treatment with a continuous positive air pressure (CPAP) device on insulin resistance evaluated by hyperinsulinemic euglycemic clamp (HEC). A prospective, randomized, open label, placebo-controlled, crossover study was performed at a tertiary outpatient pituitary center. Twelve acromegalic subjects on somatostatin analogs (SA) with a recent diagnosis of moderate to severe sleep apnea were randomized to CPAP therapy or to nasal dilator adhesive (NDA) with placebo effect for 3 months and then crossed over for another 3 months period without washout. Assessment of HEC, mathematical insulin resistance indexes (HOMA, HOMA2 and QUICKI), GH, IGF-1, HbA_1c and free fat acids were performed. A significant reduction on insulin resistance was demonstrated by HEC at the end of the study in patients on CPAP (HEC, pre- and post-CPAP: 4.27 vs. 6.10 mg/Kg/min, P = 0.032). This reduction was not observed in NDA group (HEC, pre- and post-adhesive: 5.53 vs. 5.19 mg/Kg/min, P = 0.455). There was no significant difference on HbA_1c or on peripheral insulin resistance indexes in both treatments. CPAP promoted a significant increase on peripheral insulin sensitivity in acromegalic patients with moderate to severe sleep apnea on SA use. Our results support the concept that sleep apnea plays an important role on glucose metabolism. Insulin resistance indexes were unable to detect this finding.