Increased serum levels of advanced glycation end-products is associated with severity of sleep disordered breathing but not insulin sensitivity in non-diabetic men with obstructive sleep apnoea

BackgroundPatients with diabetes mellitus are known to have increased serum levels of advanced glycation end-products (AGEs), and this is also associated with insulin resistance. This study aimed to investigate the relationship between serum AGEs and insulin sensitivity in non-diabetic subjects with obstructive sleep apnoea (OSA).MethodsAdult males with no known comorbidities were recruited from the sleep clinic of a university teaching hospital. They underwent overnight in-laboratory polysomnography. Fasting blood was taken to measure serum AGE and plasma glucose levels. Insulin sensitivity was estimated using the short insulin tolerance test.ResultsIn total, 105 subjects with a mean age of 43.5 (standard deviation [SD] 9.2) years, mean body mass index of 27.1 (SD 4.0) kg/m2, and median apnoea–hypopnoea index (AHI) of 17 (interquartile range 5–46) were analysed. Serum AGE levels were significantly higher in subjects with OSA (AHI ⩾5), compared with those without OSA (AHI <5) (3.9 [SD 1.2] vs. 3.2 [SD 0.8] μg/ml, respectively; P = 0.037) after adjusting for confounders. AGE levels were positively correlated with AHI (r = 0.318, P = 0.001), but not with insulin sensitivity. AGE levels decreased in subjects with moderate-to-severe OSA who received continuous positive airway pressure (CPAP) treatment for three months (n = 18, P = 0.017).ConclusionsSerum AGE levels correlate with AHI in non-diabetic adult males. This relationship cannot be explained by insulin sensitivity. Supporting the hypothesis of a direct relationship between AHI and AGEs, AGE levels were found to decline with CPAP therapy.