Intermittent hypoxia is an independent marker of poorer glycaemic control in patients with uncontrolled type 2 diabetes

Abstract Aim This study investigated the association between intermittent hypoxia and glycaemic control in patients with uncontrolled type 2 diabetes (T2D) not treated for sleep apnoea. Methods This was a single-centre cross-sectional study of stable patients with T2D and HbA 1c ≥7% (53mmol/mol). Patients underwent overnight pulse oximetry and, if intermittent hypoxia—defined by a 4% oxyhaemoglobin desaturation index≥15—was observed, respiratory polygraphy was performed. All participants completed the Pittsburgh Sleep Questionnaire and Hospital Anxiety and Depression Scale. The association between intermittent hypoxia and poorer glycaemic control (defined by an HbA 1c level above the median of 8.5%) was estimated by multivariate logistic regression analysis. Results Out of 145 patients studied, 54 (37.2%) had intermittent hypoxia (with sleep apnoea confirmed in 53). Patients with intermittent hypoxia had 0.7% (7.7mmol/mol) higher median HbA 1c levels than patients without intermittent hypoxia ( P =0.001). Intermittent hypoxia was associated with poorer glycaemic control after adjusting for obesity, age at onset and duration of diabetes, insulin requirement, sleep quality and depressive mood (OR: 2.31, 95% CI: 1.06–5.04, model adjusted for body mass index; OR: 2.46, 95% CI: 1.13–5.34, model adjusted for waist-to-height ratio). Conclusion Intermittent hypoxia, a consequence of sleep apnoea, is frequent and has a strong independent association with poorer glycaemic control in patients with uncontrolled T2D.