Most people with diabetes are familiar with several factors that can raise their blood glucose levels — including high-carbohydrate meals, inadequate physical activity, and not taking insulin or other medications as prescribed or directed. In some people, psychological or physical stress can also raise blood glucose levels.
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Ongoing research is also identifying other health conditions that can contribute to higher blood glucose levels in people with diabetes. One of those conditions is obstructive sleep apnea, in which the airways temporarily get blocked during sleep, stopping a person’s breathing for a period of time. Sleep apnea has been associated with a number of bad health outcomes, and a new study suggests that it’s particularly bad for people with diabetes — but that effectively treating it can help people with diabetes achieve better blood glucose control.
CPAP for better breathing, lower blood glucose
The study, published in the journal Diabetes, Obesity and Metabolism, was an analysis of seven previous clinical trials that included 691 participants with both sleep apnea and type 2 diabetes. These clinical trials all compared a standard treatment for sleep apnea — continuous positive airway pressure (CPAP), which uses a machine to support breathing while you sleep — with either a sham CPAP treatment (a machine that does nothing to support breathing) or no treatment at all.
The researchers found that compared with either a sham treatment or no treatment, CPAP lowered participants’ HbA1c (a measure of long-term blood glucose control) by an average of 0.32%. The treatment also led to improvements in fasting blood glucose and blood pressure. While the differences in HbA1c and fasting blood glucose weren’t huge in absolute terms, they were found to be statistically significant and could, over time, lead to improved outcomes in people with diabetes.
It’s notable that all of the clinical trials included in the analysis were randomized, meaning that participants didn’t know what treatment they would receive when they enrolled. This means the results are more reliable than those of observational studies — which simply look at outcomes based on what treatments people are already receiving — since people who are more motivated to treat their sleep apnea effectively may also be more motivated to control their diabetes.
Sleep apnea more common in overweight and obese people
While anyone can develop sleep apnea, it’s more common in people with excess body weight. According to Johns Hopkins Medicine, sleep apnea affects about 3% of people with a normal body weight, but over 20% of obese people. It also tends to affect men more than women, although the risk in women rises sharply after menopause.
In addition to higher blood glucose in people with diabetes, untreated sleep apnea can contribute to heart disease and metabolic problems — including, potentially, the risk of developing diabetes in people who don’t have it already. Since people with diabetes are already at higher risk for cardiovascular disease, identifying and treating sleep apnea is especially important if you’re in this group.
The signs of sleep apnea aren’t always clear to a person with the condition, since you may not be woken up by its symptoms. But a partner who sleeps with you may notice that your breathing stops for longer than usual, or that you snore loudly. It’s worth noting, though, that not everyone who snores has sleep apnea, and not everyone with sleep apnea snores.
Many people with sleep apnea wake up with a dry mouth, caused by breathing through your mouth during the night. You may also wake up with a headache, caused by inadequate oxygen intake during the night.
You may also experience fatigue or mood swings during the day if you have sleep apnea, since the condition can interfere with getting enough restful sleep. The consequences of this fatigue can be significant, potentially leading to lower productivity, falling asleep at work, and even falling asleep while driving.
If you suspect that you could have sleep apnea, talk to your doctor about getting tested for the condition.