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¹ Department of Medicine, The University of Chicago, Chicago, Illinois, United States

 

Rationale: Obstructive sleep apnea (OSA), a treatable sleepdisorder that is associated with alterations in glucose metabolismin non-diabetic individuals, is a highly prevalent co-morbidityof type 2 diabetes. However, it is not known whether the severityof OSA is a predictor of glycemic control in diabetic patients. Objective:To determine the impact of OSA on hemoglobin A1c (HbA1c), themajor clinical indicator of glycemic control, in patients withtype 2 diabetes. Methods: We performed polysomnography studiesand measured HbA1c in 60 consecutive diabetic patients recruitedfrom outpatient clinics between February 2007 and August 2009.Measurements and Main Results: Seventy-seven percent of diabeticpatients had OSA (apnea-hypopnea index [AHI] 5). IncreasingOSA severity was associated with poorer glucose control, aftercontrolling for age, sex, race, BMI, number of diabetes medications,level of exercise, years of diabetes and total sleep time. Comparedto patients without OSA, the adjusted mean HbA1c was increasedby 1.49% (p=0.0028) in patients with mild OSA, 1.93% (p=0.0033)in patients with moderate OSA, and 3.69% (p<0.0001) in patientswith severe OSA (p< 0.0001 for linear trend). Measures ofOSA severity, including total AHI (p=0.004), REM AHI (p=0.005),and the oxygen desaturation index during total and REM sleep(p=0.005 and p=0.008, respectively) were positively correlatedwith increasing HbA1c levels. Conclusions: In patients withtype 2 diabetes, increasing severity of OSA is associated with poorer glucose control, independent of adiposity and other confounders,with effect sizes comparable to those of widely used hypoglycemicdrugs.