Risk for obstructive sleep apnea in obese, nondiabetic adults varies with insulin resistance status

Obstructive sleep apnea (OSA) is an increasingly common sleep disorder, especially among obese adults. Early identification of adults at risk for OSA would be of substantial benefit; however, the magnitude of the obesity epidemic requires that screening be performed judiciously. The study's aim was to utilize questionnaires that assess OSA risk and symptoms to test the hypothesis that the most insulin-resistant subset of obese individuals is at highest risk for OSA.

Nondiabetic, overweight to obese volunteers underwent direct quantification of insulin sensitivity by measuring steady-state plasma glucose concentrations during the insulin suppression test. Insulin-sensitive and insulin-resistant individuals were administered the Berlin and STOP questionnaires to determine OSA risk status, and Epworth Sleepiness Scale (ESS) to evaluate daytime sleepiness. Fasting insulin and lipid/lipoprotein measurements were performed.

Insulin-mediated glucose disposal differed threefold (p < 0.001) between equally obese, insulin-resistant (n = 22) and insulin-sensitive (n = 14) individuals, associated with higher fasting insulin and triglyceride and lower high-density lipoprotein cholesterol (HDL-C) concentrations in insulin-resistant individuals. Fourteen (64 %) insulin-resistant as compared with 2 (14 %) insulin-sensitive individuals were found to be at high risk for OSA by both questionnaires (p < 0.01). Whereas half of insulin-resistant individuals met the ESS criteria for excessive daytime sleepiness, only one insulin-sensitive individual did (p = 0.011).

High risk for OSA and excessive daytime sleepiness is prevalent among the insulin-resistant subgroup of obese individuals. Surrogate estimates of insulin resistance based on fasting insulin, triglycerides, and/or HDL-C can be used to help identify those obese adults who would benefit most from OSA screening and referral for polysomnography.