Does CPAP Help Glycemic Control?

Some studies have suggested that people with diabetes and poor glycemic control may benefit from the use of continuous positive airway pressure (CPAP). The results of a randomized and controlled trial published in the American Journal of Respiratory and Critical Care Medicine report that this may not be true.

It has been suggested that obstructive sleep apnea (OSA) is a major contributor to the development of type 2 diabetes mellitus; however, proving that link has been a challenge. Interventional studies would be required to show that correcting OSA would improve glycemic control in diabetics. The most recent research suggests contradictory findings, with some uncontrolled studies showing improved glycemic control with the use of CPAP, and some controlled studies negating those findings.

In a study out of Australia and the US, about 300 patients with somewhat well-controlled type 2 diabetes, along with a new diagnosis of obstructive sleep apnea, were separated into two groups: those who had their sleep apnea treated with CPAP and those who underwent other conventional care.

Researchers monitored glycemic control, as well as any changes in blood pressure, quality of life, and daytime fatigue over the following six months. What was found was the following:

  • There was no difference between the two groups with regards to hemoglobin A1c levels in three to six months’ time.
  • Previous studies showed that those who used CPAP for more than four hours at night had a drop in diastolic blood pressure, which correlates with this research that found a dramatic decrease in the diastolic number among those receiving CPAP treatment.
  • Excess sleepiness during the day was decreased in those who were using CPAP.
  • Quality of life was not statistically significant between the two groups; however, among those patients who were receiving CPAP, there was a difference in mental health and vitality scores.

Scientists suggest the theories that CPAP may not improve glycemic control in those with already established diabetes, but may still in fact help prevent the development of type 2 diabetes. Additionally, in the above study, CPAP was only used for four hours a night, which may have been set too low to make any real difference. Finally, researchers suggest that CPAP may only be helpful in those with severe OSA or poor glycemic control.

While this study does not show CPAP to be helpful in controlling blood sugars, it is worthy to note that OSA could be a contributing factor to worsening diabetes if the patient is experiencing daytime sleepiness, resistant hypertension, or snoring. There may be clinically significant benefits in treating OSA in these diabetic patients; however, more studies are needed.

It is worthy to note that, recently, another study published in the American Journal of Respiratory and Critical Care Medicine reviewed glycemic control and the use of CPAP in patients who did not have well-controlled diabetes. This was also a six-month randomized trial, but it showed that CPAP did in fact significantly improve glycemic control at six months; however, there was no difference noted at three months.

Further research is recommended in order to further delineate the actual benefits of CPAP in diabetic patients.


Author: Rachael Herman is a professional writer with an extensive background in medical writing, research, and language development. Her hobbies include hiking in the Rockies, fishing, and reading.


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