Purpose: The study aimed at assessing glucose control measured with a continuous glucose monitoring system (CGMS) before and after short-term continuous positive airway pressure (CPAP).
Materials and Methods: Twenty-four type 2 diabetic patients (T2DM) with Obstructive sleep apnea syndrome (OSAS) (mean age 55.0 ± 9.0 years; BMI 29.5 ± 5.2 kg/m²) were admitted and kept under diet control for 2 days, then underwent 2 overnight polysomnographies: a diagnostic study and one with CPAP titration. Then they were treated by CPAP during sleep for the following three nights. Participants were divided into subgroup D (only diet control) and subgroup M (with DM medication). CGMS was utilized over the last five days. Glucose control was also assessed with plasma insulin and a clinical measure of insulin resistance (HOMA-IR) index.
Results: The mean (±SD) apnea-hypopnea index (AHI) at diagnostic polysomnography was 51.2 ± 22.4 (range 10– 88) events/h. CPAP treatment in the subjects with OSAS resulted in the index of oxygenation desaturations being reduced from 33.3 ± 20.1 to 1.1 ± 1.6 (P =0.00). CGMS showed mean 24-hours glucose values significantly lower after CPAP treatment than at baseline in both subgroups (7.97± 1.31 vs 7.52± 0.94, P=0.033 in subgroup D; and 7.72± 1.51 vs 7.17± 1.21, P=0.05 in subgroup M), as the fasting plasma insulin levels and HOMA-IR were also decreased significantly after CPAP treatment (13.0 ± 7.5μU/mL vs 10.8 ± 5.4μU/mL, P=0.044; and 4.2 ± 2.2 vs 3.1± 1.7, P=0.003, respectively). Standard deviation (SD) and mean amplitude of glucose excursions (MAGE) were also decreased in the subgroup D (1.91 ± 1.10 vs 1.61 ± 1.20, P=0.014; 1.26 ± 1.13 vs 1.01 ± 0.98, P=0.008, respectively) only.
Conclusion: Short-term CPAP treatment in OSAS with type 2 diabetic patients is accompanied by a decrease in blood glucose level and improved insulin sensitivity. Glucose variability was reduced but only in the patients with diet control.
Keywords: type 2 diabetes mellitus, obstructive sleep apnea syndrome, continuous positive airway pressure, continuous glucose monitoring system, glucose variability, HOMA-IR