Postprandial glucose and HbA1c are associated with severity of obstructive sleep apnoea in non-diabetic obese subjects
Angelo Cignarelli, Alessandro Ciavarella, Maria Pia Foschino Barbaro, Stella Kounaki, Antonio Trani, Vito Antonio Falcone, Vitaliano Nicola Quaranta, Annalisa Natalicchio, Luigi Laviola, Onofrio Resta, Francesco Giorgino, Sebastio Perrini
Abstract
Abstract Introduction Obstructive sleep apnoea (OSA) is an underdiagnosed condition frequently associated with glycaemic control impairment in patients with type 2 diabetes. Aim To assess the relationship between glycometabolic parameters and OSA in obese non-diabetic subjects. Methods Ninety consecutive subjects (mean age 44.9 ± 12 years, mean BMI 42.1 ± 9 kg/m 2 ) underwent polysomnography and a 2-h oral glucose tolerance test (OGTT). Results OSA was identified in 75% of subjects, with a higher prevalence of males compared to the group of subjects without OSA (62% vs 32%, p = 0.02). Patients with OSA had comparable BMI (42.8 kg/m 2 vs 39.4 kg/m 2 ), a higher average HbA1c (5.8% vs 5.4%, p < 0.001), plasma glucose at 120 min during OGTT (2 h-PG; 123 mg/dl vs 97 mg/dl, p = 0.009) and diastolic blood pressure (81.1 mmHg vs 76.2 mmHg, p = 0.046) than obese subjects without OSA. HbA1c and 2 h-PG were found to be correlated with the apnoea-hypopnoea index (AHI; r = 0.35 and r = 0.42, respectively) and with percent of sleep time with oxyhaemoglobin saturation < 90% (ST90; r = 0.44 and r = 0.39, respectively). Further, in a linear regression model, ST90 and AHI were found to be the main determinants of 2 h-PG ( β = 0.81, p < 0.01 and β = 0.75, p = 0.02, respectively) after controlling for age, sex, waist circumference, physical activity, and C-reactive protein. Similarly, ST90 and AHI persisted as independent determinants of HbA1c ( β = 0.01, p = 0.01 and β = 0.01, p = 0.01, respectively). Conclusion Beyond the traditional clinical parameters, the presence of a normal-high value of 2 h-PG and HbA1c should raise suspicion of the presence of OSA in obese subjects.