Can obstructive sleep apnea affect blood glucose levels in type 2 diabetics?

This study examined whether obstructive sleep apnea occurring during a deep sleep can influence long-term control of blood glucose levels.  

Obstructive sleep apnea (OSA) is a condition in which the muscles in the back of the throat relax while sleeping. This results in the breathing repeatedly starting and stopping. OSA could be serious if the individual stops breathing for a long period. The most common symptom of OSA is snoring. Patients with type 2 diabetes (T2D) and OSA have poor control of blood glucose (sugar) levels.

OSA can be treated with continuous positive airway pressure (CPAP – mild air pressure is applied to keep airways open). CPAP is generally more effective in the first half of the night when an individual is in a light sleep. Treatment is not as effective when patients are in a deep sleep. It is unknown whether the negative effect that OSA has on blood glucose levels occurs during a light sleep or a deep sleep. 

This study aimed to determine the effect of OSA on long-term control of blood glucose levels during a light and a deep sleep.

This study involved 115 T2D patients. Participants underwent a sleep study and the HbA1C (average blood glucose levels over 3 months) was measured.

OSA which occurred during light sleep was not associated with high blood glucose levels. However, OSA which occurred during deep sleep was associated with higher blood glucose levels (increase in HbA1c by an average of 1%).

These results predict that 4 hours (average time per night) of CPAP would prevent OSA occurring in a deep sleep 40% of the time and would only decrease the HbA1c by 0.25%. However, 7 hours of CPAP may prevent OSA occurring in a deep sleep 85% of the time. 7 hours of CPAP may also decrease the HbA1c by 1%.

This study concluded that OSA during deep sleep is associated with poorer control of blood glucose levels. In addition, 4 hours of CPAP treatment per night may not be sufficient to improve blood glucose levels.

The authors only looked at the impact of OSA on the HbA1c. It may have been ideal to assess whether OSA had an effect on insulin (hormone which reduces blood glucose levels) secretion.

Consult your physician regarding the treatments available for OSA.