Misa Valo, Albert Moller and Claudius Teupe
Introduction: Diabetes Mellitus (T2DM) and obstructive sleep apnea (OSA) are common disorders that often coexist. Both disorders are associated with an increased risk of cardiovascular complications. Repeated nocturnal hypoxia in diabetic patients suffering also from OSA may result in myocardial ischemia. We evaluated whether myocardial ischemia is detectable by ST-segment depression and elevation of high sensitive Troponin T (hs-cTnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP). We also examined the effect of continuous positive airway pressure treatment (CPAP) on these markers. Methods: Fifteen patients with OSA and concomitant T2DM and 26 patients with OSA alone underwent polysomnography at baseline and under CPAP. Blood samples for hs-cTnT and NT-proBNP measurements were drawn prior and immediately after sleep. ST-segment depression was measured at the time of maximum oxygen desaturation during sleep. Results: The apnea-hypopnea-index and oxygen saturation nadir were similar in both groups. Levels of hscTnT and NT-proBNP did not differ significantly before and after baseline polysomnography and CPAP respectively within the same group. But hs-cTnT levels were significantly higher before and after PSG and CPAP respectively in patients suffering from T2DM and OSA compared to patients with OSA alone. In both groups, we found no significant ST-segment depression at the time of oxygen saturation nadir. Conclusions: Despite the fact that patients with T2DM and coexisting OSA experienced severe nocturnal hypoxemia we were unable to detect myocardial ischemia or myocyte necrosis evidenced by significant ST-segment depression or elevation of hs-cTnT and NT-proBNP respectively. CPAP had no influence on hs-cTnT and NTproBNP levels