Sleep Apnea and Diabetes: Why Blood Sugar and Sleep Are Linked

Why sleep apnea and type 2 diabetes often go together, how poor breathing at night affects blood sugar, and when to get a sleep test.

R. Murali7 November 20263 min read

Diabetes and sleep apnea often travel together. Many people with type 2 diabetes have obstructive sleep apnea without knowing it, and untreated sleep apnea can make blood sugar harder to control. If you have diabetes and you snore or wake up tired, a sleep test is worth discussing with your doctor.

How poor breathing at night affects blood sugar

Broken sleep and low oxygen at night can raise blood sugar the next day.

Every time the airway closes during sleep, oxygen drops and the body releases stress hormones such as adrenaline and cortisol. These hormones raise blood sugar and make the body's cells respond less well to insulin, which is called insulin resistance. Sleep is also broken into fragments, and poor-quality sleep on its own worsens insulin resistance and increases appetite for sugary food the next day.

The link works the other way too. Excess weight around the neck and belly, common in type 2 diabetes, narrows the airway, and diabetes can affect the nerves that control breathing. So each condition can feed the other.

How common is it?

Studies of people with type 2 diabetes, especially those who are overweight, have found obstructive sleep apnea in a large majority, and most of them had never been diagnosed. This is why international diabetes organisations advise doctors to think about sleep apnea in people with type 2 diabetes who have symptoms.

Warning signs if you have diabetes

Loud snoring, or a partner who notices pauses or gasps in your breathing
Waking tired, or dozing off during the day
Morning sugar readings that are high without an obvious reason
High blood pressure as well as diabetes
Waking several times a night to pass urine
Morning headaches

Will treating sleep apnea help my diabetes?

Treating sleep apnea improves sleep, energy and blood pressure in most people who use CPAP regularly. Its effect on blood sugar is more modest: some studies show better insulin sensitivity and night-time sugar levels, especially with good nightly use, while the effect on HbA1c over a few months has been small and varies from person to person. Better sleep also makes it easier to stick to diet and exercise, which matter most for diabetes.

Sleep study and CPAP therapy in Chennai

Home sleep test with Scala / SAMOA, Sonata polysomnography in our sleep lab — and the CPAP or BiPAP therapy that follows.

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In short, treating sleep apnea is not a cure for diabetes, but it removes one thing that is working against you, and it protects your heart, which matters a great deal when you have diabetes.

Getting tested

For most adults with diabetes, a home sleep study is the easiest first step: one night in your own bed, with the report reviewed by a sleep physician. If you have heart or lung problems as well, your doctor may suggest a lab study. Not sure whether you need a test? Try our 1-minute snoring check.

Frequently asked questions

Can sleep apnea cause diabetes?

Sleep apnea is linked to a higher risk of developing type 2 diabetes, through insulin resistance and broken sleep, but it is one factor among several, including weight, diet, activity and family history.

Should I change my diabetes medicine if I start CPAP?

Not on your own. Keep checking your sugar as usual and let your doctor review your medicines if your readings change.

Is sleep apnea more common in people with diabetes and obesity?

Yes. Extra weight around the neck narrows the airway, so the risk is highest when diabetes and obesity occur together, though slim people can have sleep apnea too.

1-minute check