Obstructive sleep apnea (OSA) is associated with obesity and risk for type 2 diabetes. In this community-based study, we thoroughly investigated fatty acid metabolism, incretin response, glucose tolerance, insulin secretion and insulin sensitivity, and autonomic nerve activity in men with or without OSA.
Fifteen men without diabetes but with signs of severe OSA, defined as apnea-hypopnea index (AHI) >30, and 15 age- and BMI-matched men without OSA (AHI < 5) were recruited from a community-based cohort. Assessments included clinical and anthropometric measurements, a 2-h oral glucose tolerance test (OGTT), and autonomic nerve activity using heart rate variability (HRV).
Men with OSA had higher body fat % than BMI-matched men without OSA (p = 0.046) and it was associated with markers of insulin resistance. The area under the curve for nonesterified fatty acids (NEFA) during OGTT was higher in men with OSA (p = 0.021) and fasting NEFA levels were numerically higher (p = 0.097). The plasma glucose at fasting and during OGTT was higher in men with OSA (p < 0.001). Incretin response was similar between groups. Fasting and OGTT-derived indices indicated impaired insulin sensitivity in men with OSA. Compared with men without OSA, Matsuda index (p = 0.068) and Gutt index (p < 0.01) were lower in men with OSA. The HRV measures did not differ between groups.
Our study suggests that fatty acid handling, glucose tolerance, and insulin sensitivity are impaired in men with severe OSA. This might partly be explained by the increased body fat percentage.