A Randomized Controlled Trial of Continuous Positive Airway Pressure on Glucose Tolerance in Obese Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is associated with an increased prevalence of metabolic syndrome (MetS), even in patients with morbid obesity. Our goal was to address whether continuous positive airway pressure (CPAP) treatment improved glucose metabolism in this population. A prospective randomized controlled trial was performed in severe OSA patients with morbid obesity without diabetes in two university referral hospitals. Patients received conservative (CT) versus CPAP treatment for 12 weeks. MetS components, homeostasis model assessment of insulin resistance (HOMA-IR) and oral glucose tolerance were assessed at baseline and after treatment. A total of 80 patients completed the study (42 CPAP and 38 CT patients). After 12 w of CPAP treatment, weight loss was similar in both groups and physical activity, prevalence of MetS, and HOMA-IR did not change in either group. In the CPAP group impaired glucose tolerance (IGT) reversed in nine patients and IGT developed in none, whereas IGT reversed in five patients and IGT developed in five patients in the CT group (P = 0.039 in the Fisher test). Changes in 2-h plasma glucose after glucose load were greater in the CPAP group than in the CT group (CPAP: −0.5 ± 1.5 versus CT: 0.33 ± 1.9, P = 0.007). The improvement of glucose tolerance in morbidly obese patients with severe obstructive sleep apnea, without changes in homeostasis model assessment of insulin resistance, supports an improvement in peripheral insulin resistance after continuous positive airway pressure treatment. NCT 01029561. Observational studies have suggested that obstructive sleep apnea (OSA) is associated with impaired glucose metabolism and metabolic syndrome. To date, it remains unclear whether sleep apnea treatment with CPAP is beneficial for glucose metabolism. This is the first study to investigate the effects of CPAP on glucose metabolism in a specific population of morbidly obese patients. These patients represent an extreme model for studying the relation between OSA and metabolic dysfunction because of an increased risk for both disorders. We demonstrated that an effective treatment of OSA with CPAP improves glucose tolerance in morbidly obese patients with severe OSA, without changes in HOMA-IR or metabolic syndrome. These results support an improvement in peripheral insulin resistance after CPAP treatment.