A group of 31 participants with established obstructive sleep apnea were randomized to continue or stop CPAP. Patients were analyzed for several metabolic variables. Untreated individuals experienced higher levels of serum cortisol, glucose and systolic blood pressure among other alterations.

Such anomalies are well known risk factors for development of diabetes, hypertension and cardiovascular illness. It is important to screen, diagnose and treat patients with obstructive sleep apnea. Adherence to therapy needs to be emphasized too.

J C E M

Randomized Crossover

September 2017

Context: Obstructive sleep apnea (OSA) is associated with diabetes and cardiovascular disease. This association may be related to metabolic changes that transpire during sleep in OSA.

Objective: To examine the impact of OSA, elicited by cessation of continuous positive airway pressure (CPAP), on frequently sampled nocturnal metabolic markers including: plasma free fatty acids (FFAs), glucose, insulin, triglycerides (TGs), cortisol, and lactate, as well as glucose production, oral glucose tolerance, blood pressure (BP), endothelial function, cholesterol, and high-sensitivity C-reactive protein (hsCRP).

Design and Setting: Randomized crossover trial of CPAP vs CPAP withdrawal.

Patients: 31 patients with moderate to severe OSA acclimated to CPAP.

Intervention: Patients underwent attended polysomnography while sleeping with therapeutic CPAP, or after CPAP withdrawal, in random order. Venous blood was sampled at ∼20-minute intervals on both nights. In 11 patients, we assessed glucose kinetics with an infusion of 6,6-[2H2]glucose.

Results

CPAP withdrawal caused recurrence of OSA associated with hypoxemia, sleep disruption, and heart rate (HR) elevation.

CPAP withdrawal dynamically increased nocturnal FFA (P = 0.007), glucose (P = 0.028), and cortisol (P = 0.037), in proportion to respiratory event frequency, HR elevation, or sleep fragmentation.

Diabetes predisposed to glucose elevation. CPAP withdrawal also increased systolic BP (P = 0.017) and augmentation index (P = 0.008), but did not affect insulin, TGs, glucose production, oral glucose tolerance, cholesterol, or hsCRP.

Conclusion

OSA recurrence during CPAP withdrawal increases FFA and glucose during sleep, associated with sympathetic and adrenocortical activation. Recurring exposure to these metabolic changes may foster diabetes and cardiovascular disease.