Obstructive sleep apnea and type 2 diabetes

I saw a 62-year-old gentleman for type 2 diabetes. He was on metformin and sitagliptin in addition to four antihypertensive medications. His HbA1c was 8.2% and blood pressure 148 mm Hg/83 mm Hg. He was sent to see me because he had driven his car into a ditch. Concerns were raised that it might be due to hypoglycemia.

I walked into the room and found an obese man slouched in his chair snoring loudly. After a few pats on the shoulder he awakened. As long as he could remember he fell asleep frequently during the day and always felt tired. He snored so loudly that a few years ago his wife began sleeping in another room. Even his adult children stayed in a hotel rather than at home when they came to visit.

Review of his finger stick blood glucose records showed no hypoglycemia at all. Indeed, most of his glucoses were too high. I doubted that hypoglycemia was the cause. Metformin and sitagliptin in the absence of hypoglycemic agents are unlikely to cause hypoglycemia. I ordered a sleep study which confirmed severe obstructive sleep apnea.

Obstructive sleep apnea is strongly associated with type 2 diabetes. Studies have found that 23% to 36% of men with type 2 diabetes have obstructive sleep apnea compared with only 5% to 10% of the general population. It is no surprise that obstructive sleep apnea and type 2 diabetes are associated; the risk of both is increased by the presence of obesity.

However, there is evidence that obstructive sleep apnea may be an independent risk factor for type 2 diabetes and poor glycemic control. Some studies have shown that the use of continuous positive airway pressure reduces insulin resistance and improves glycemic control. Obstructive sleep apnea is also associated with hypertension, increased cardiovascular risk and other cardiometabolic abnormalities. The cause has not yet been fully elucidated but is believed to be due to a variety of factors including increased sympathetic nervous system activity, elevated catecholamines, hypoxia, sleep deprivation, endothelial dysfunction and abnormal release of cytokines.

After some trepidation, our patient began using CPAP regularly. At a follow-up visit three months later accompanied by his wife, he said he felt the best he had in years. He was no longer exhausted and irritable during the day and had the energy to begin exercising regularly. His glycemic control and blood pressure improved and he even lost 5 lb. We were able to stop two of his antihypertensive medications.

He and his wife smiled and said: “And the best part is: we’re not sleeping in different rooms anymore!”

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