Nocturnal hypoxaemic burden is associated with incident major adverse cardiovascular events in patients with type 2 diabetes

Abstract Aims Type 2 diabetes (T2D) prevalence is globally increasing and associated with cardiovascular disease. Whether oximetry-derived nocturnal hypoxaemic burden (NHB) parameters are associated with incident major adverse cardiovascular events (MACE) in a population with T2D is not known. Methods and results Overnight oximetry data from patients enrolled in the DIACORE (DIAbetes COhoRtE) sleep-disordered breathing sub-study, a prospective German cohort study of patients with T2D, were analysed. Nocturnal hypoxaemic burden as cumulative time spent below 90% oxygen saturation (T90) as well as its composition of T90 attributed to acute desaturations (T90desaturation) and non-specific drifts in oxygen saturation (T90non-specific) was assessed. Major adverse cardiovascular event was defined as a composite outcome of myocardial infarction, stroke, and cardiovascular death. Cox hazard regression analyses adjusted for potential known risk factors for atherosclerosis were conducted. The analysis population consisted of 1255 participants (41% female, mean age 67 years, mean diabetes duration 9.6 years). After a median follow-up of 6.5 years, a MACE occurred in 149 (12%) patients. T90, but not apnoea-hypopnoea index, was significantly associated with an increased risk of incident MACE by 48% independently of other known risk factors for atherosclerosis [Quartile 4 vs. Q1–3 adjusted hazard ratio (HR) 1.48, 95% confidence interval (CI) (1.04; 2.12), P = 0.032]. In particular, T90non-specific contributed to the elevated risk for incident MACE [Q4 vs. Q1–3 adjusted HR 1.62, 95% CI (1.14–2.30), P = 0.007]. Conclusion In the present study, NHB was associated with MACE in patients with T2D and can be easily measured using oximetry. Further investigations are warranted to establish T90 reduction as a clinically meaningful treatment target.