Sleep Apnea and Type 2 Diabetes: How They Are Linked

Obstructive sleep apnea (OSA) and type 2 diabetes often go together. Sleep apnea can make the body less sensitive to insulin and is linked to a higher chance of getting diabetes, while extra weight raises the risk of both. Treating sleep apnea helps sleepiness, quality of life and blood pressure, but its effect on blood sugar is small or mixed, so it works alongside your diabetes care, not instead of it.

How common is sleep apnea in type 2 diabetes?

Very common. The American Diabetes Association (ADA) notes that up to about 1 in 4 people with type 2 diabetes have obstructive sleep apnea, and more have some breathing trouble during sleep.^[2] In one large study of adults with type 2 diabetes and obesity, more than 80% had sleep apnea.^[2]

Many of these people do not know they have it. Snoring and tiredness are easy to blame on other things, including diabetes itself.

A two-way link

Sleep apnea may raise diabetes risk. A review of six long-term studies found that people with moderate to severe sleep apnea had about a 60% higher risk of developing type 2 diabetes than people without it.^[1] The authors concluded that sleep apnea appears to be a risk factor on its own.^[1]

Diabetes may affect breathing in sleep, too. Researchers think high blood sugar over many years may affect the nerves that help control breathing. This direction is less well studied.

Weight connects both. Extra weight, especially around the belly and neck, raises the risk of both conditions.

How sleep apnea affects blood sugar

Each time breathing stops, several things happen in the body that can push blood sugar up:

• Oxygen drops — repeated dips in oxygen make cells less sensitive to insulin.
• Stress hormones surge — the body's "fight or flight" response releases hormones that raise blood sugar.
• Sleep gets broken — poor sleep can change hunger hormones and make the body handle sugar less well.
• Inflammation rises — ongoing low-level inflammation can make insulin resistance worse.

The same stress response raises blood pressure. If you have both diabetes and high blood pressure, see sleep apnea and high blood pressure.

Who should be checked for sleep apnea?

The ADA lists screening for sleep apnea as part of routine diabetes visits, and says people with suggestive symptoms should be evaluated.^[2] Ask about a sleep test if you have diabetes and any of these:

• Loud snoring — especially snoring with gasps or snorts.
• Pauses in breathing — seen by a bed partner.
• Daytime sleepiness — dozing while reading, watching TV or driving.
• Morning headaches or waking up to urinate often — these can have other causes, but are worth mentioning.
• Hard-to-control blood pressure or obesity — both make sleep apnea more likely.

Many adults can be tested at home. See home sleep apnea testing.

What CPAP does and does not do for blood sugar

CPAP keeps the airway open during sleep. It clearly helps daytime sleepiness and quality of life. Its effect on blood sugar is less certain:

• Some trials show a small benefit — in people whose diabetes was not well controlled, six months of CPAP lowered A1c more than no CPAP.^[3]
• Others show no change — a large trial in people with fairly well-controlled diabetes found no effect on A1c, although sleepiness and quality of life improved.^[4]
• Pooled results are modest — combining 11 trials, CPAP lowered A1c by about a quarter of a percentage point on average.^[5]
• Hours matter — the benefit was larger in people who used CPAP more hours each night.^[5] See CPAP compliance tips.

CPAP is not a diabetes medicine. Keep taking your diabetes medicines as prescribed and keep up with your A1c checks.

That does not make treatment less worth it. Feeling more awake can make it easier to stay active, plan meals and keep up with the daily work of managing diabetes. Treating sleep apnea also lowers blood pressure a little in many people, which matters because diabetes and high blood pressure both strain the heart and blood vessels. If CPAP is hard to use, tell your sleep doctor: mask changes, pressure changes and other treatment options can help.

Weight loss and weight-loss medicines

Losing weight can lower sleep apnea severity and help blood sugar at the same time. Our weight loss and sleep apnea post covers how much it helps.

• Zepbound (tirzepatide) — in December 2024, the FDA approved it for moderate to severe obstructive sleep apnea in adults with obesity, used with diet and exercise.^[6] The same medicine is sold as Mounjaro for type 2 diabetes.
• Diabetes was not studied — the main sleep apnea trials left out people with diabetes, so the ADA says more research is needed in people with diabetes.^[2]
• Keep using CPAP — don't stop treatment while you lose weight. Your sleep doctor can tell you when a repeat sleep study makes sense.

When to see a sleep specialist

See a sleep doctor if you have diabetes and snore loudly, feel sleepy during the day, or someone has seen you stop breathing in sleep. Also check in if you already use CPAP but still feel tired, or if your weight has changed a lot. More signs are in when to see a sleep specialist.

Sleep apnea care in Cedar Park

Dr. Minal Patel is board-certified in pediatrics and sleep medicine. Our practice offers in-lab and home sleep studies, CPAP and BiPAP therapy, and Inspire evaluation. We are accepting new patients. Office hours are Monday through Friday, 8:30 to 5:00. We accept Medicaid and CHIP for sleep patients. We do not take walk-ins.