Type 2 diabetes, glycemic control, and continuous positive airway pressure in obstructive sleep apnea

Sleep-disordered breathing (SDB) is a prevalent condition associated with significant comorbidities, including hypertension, obesity, cardiovascular disease, and insulin resistance. It has been previously shown that the severity of insulin resistance is related to the severity of SDB.

Using a 72-hour continuous glucose monitoring system, we studied changes in interstitial glucose levels and measured hemoglobin A1c levels in 25 patients with type 2 diabetes mellitus before and after continuous positive airway pressure (CPAP) treatment for SDB.

With a mean +/- SD CPAP treatment period of 83 +/- 50 days, the mean +/- SD 1-hour postprandial glucose values were significantly reduced for breakfast (191 +/- 68 mg/dL to 130 +/- 41 mg/dL [10.6 +/- 3.8 mmol/L to 7.2 +/- 2.3 mmol/L]), lunch (196 +/- 70 mg/dL to 138 +/- 49 mg/dL [10.9 +/- 3.9 mmol/L to 7.7 +/- 2.7 mmol/L]), and dinner (199 +/- 66 mg/dL to 137 +/- 48 mg/dL [11.0 +/- 3.7 mmol/L to 7.6 +/- 2.7 mmol/L]). In the 17 patients with a baseline hemoglobin A1c level greater than 7%, there was a significant reduction in hemoglobin A1c level (9.2% +/- 2.0% to 8.6% +/- 1.8%). Furthermore, in subjects who used CPAP for more than 4 h/d, the reduction in hemoglobin A1c level was significantly correlated with days of CPAP use. There was no such correlation in subjects who used CPAP for 4 h/d or less.

These findings suggest that SDB is pathophysiologically related to impaired glucose homeostasis, and that CPAP can be an important therapeutic approach for diabetic patients with SDB.