Effect of glycemic control on nocturnal arterial oxygen saturation: A case-control study in type 2 diabetic patients

© 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd. Background: There is growing evidence suggesting a deleterious effect of type 2 diabetes on lung function and sleep breathing. The aim of this case-control study was to evaluate whether or not an improvement in glycemic control could arrest or ameliorate nocturnal hypoxemia in type 2 diabetes. Methods: Thirty patients with type 2 diabetes with HbA1c ≥8% (cases) and 10 non-diabetic subjects were analyzed. Controls were closely matched to cases by age, gender, body mass index, and neck circumference. The nocturnal oxygen desaturation index (ODI) was calculated at baseline and 5 days after blood glucose improvement with pharmacological intervention. Four different oxygen desaturation thresholds (reductions in SaO2≥3%, 4%, 6%, and 8%) as indicators of hypoxemia severity (ODI-3%, ODI-4%, ODI-6%, ODI-8%) were used. Results: At baseline, patients with diabetes showed a higher number of ODI-3%, ODI-4%, and ODI-6% in comparison with controls. A significant reduction in ODI-3% (29.7 [4.8-107.9] events per hour at baseline versus 24.6 [3.1-97.7] e/h at discharge, P<0.001), ODI-4% (21.7 [1.6-79.3] versus 14.7 [0.3- 79.4], P=0.003), ODI-6% (9.3 [0.3-71.8] versus 4.0 [0.0-73.7], P=0.001), and ODI-8% (4.1 [0.0-64.3] versus 1.1 [0.0-69.8], P=0.033) was observed in patients with diabetes after 5 days of follow-up. However, no changes in ODI events were observed in non-diabetic patients after the same period. No significant changes in weight were observed in either group. Conclusions: Glycemic control improvement significantly reduces the increased number of nocturnal oxygen desaturations that exist in type 2 diabetes. Although the mechanisms are not yet fully understood, the rapid effect without changes in body weight suggests a central mechanism involving respiratory center output.