Effect of CPAP therapy on dynamic glucose level in OSAHS patients with newly diagnosed T2DM

Abstract

To investigate the characteristic of dynamic glucose level in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients with newly diagnosed type 2 diabetes mellitus (T2DM) and to evaluate the effect of continuous positive airway pressure (CPAP) treatment on the glucose level. A total of 65 cases of patients with T2DM who were newly diagnosed by oral glucose tolerance test (OGTT) were enrolled from April 2014 to April 2015 in Gansu Provincial Hospital, and divided into simple T2DM group (n=30) and OSAHS with T2DM group (n=35) according to aponea-hypopnea index (AHI) which was monitored by polysomnography (PSG). Their general clinical data were collected, and glucose level of different periods was monitored by continuous glucose moitoring system (CGMS). Changes of glucose level were compared between two groups before and after CPAP treatment. Age, gender proportion, BMI, smoking and drinking history, glycosylated hemoglobin (HbA1c) and blood lipid profile had no significantly difference between two groups. Longer neck circumstance and higher waist-hip ration (WHR), higher systolic blood pressure and diastolic blood pressure, higher fasting plasma glucose (FPG) [(9.4 ± 3.2) vs (7.3 ± 2.1) mmol/L, P=0.028] and fasting insulin (FINS) [(19.2 ± 8.7) vs (11.1 ± 4.7) mU/L, P=0.044] level, more serious homeostasis model assessment insulin resistance (HOMA-IR) were found in OSAHS patients with T2DM when compared to patients in simple T2DM group. The average dynamic glucose level of 24 hours, daytime, nocturnal and sleep time in OSAHS with T2DM group were higher than that in the simple T2DM group (all P<0.05). The alarming times when the average dynamic glucose level of nocturnal time was more than 0.1 mmol·L⁻¹·min⁻¹ in T2DM with OSAHS was more than that in control group (P=0.001). After treatment of CPAP, the level of AHI [(5.9 ± 3.6) vs (56.7 ± 11.4) times/h, P<0.001], average dynamic glucose level of 24 hours, day, nocturnal and sleep time were obviously decreased (all P<0.05); lowest saturation oxygen (LSpO₂) was significantly increased [(92.3 ± 3.7)% vs (81.5 ± 20.2)%, P<0.001]; the alarming times and HOMA-IR were obviously decreased (P=0.019, 0.043). According to multiple linear regression analysis, the AHI (β=0.736, P<0.001) in OSAHS with T2DM group was positively related to the average dynamic glucose level during sleep time, but the LSpO₂(β=-0.889, P<0.001) was negatively correlated. OSAHS patients with newly diagnosed T2DM have higher glucose level than that in simple T2DM patients, and CPAP therapy can obviously decrease the glucose level in newly diagnosed T2DM patients with OSAHS. AHI and LSpO₂may influence the average dynamic glucose level during sleep time.