I see the connection between disordered sleep and diabetes all the time in my practice, as I work with patients who are coping with metabolic problems and sleep problems at the same time. Irregular sleep schedules and sleep disorders can increase risks for diabetes—and they also make managing the disease more difficult.
We’ve looked at the underlying ways that sleep contributes to diabetes—now let’s take a closer look at the specific sleep disorders that influence the condition, and the diabetes symptoms that can interfere with sleep.
The Obstructive Sleep Apnea-Diabetes connection
Before we look at the broader range of sleep issues and sleep disorders that occur with diabetes, I want to discuss the relationship between diabetes and obstructive sleep apnea. It’s an important one, because of how often the two conditions occur together. OSA is the most common sleep disorder in people with diabetes. As research has shown, a majority of people with diabetes—as many as 86 percent—also have obstructive sleep apnea. People with diabetes are at increased risk for OSA and people with OSA are at higher risk for diabetes.
The relationship between OSA and diabetes is complex, and scientists are still working to understand how the two conditions affect one another. But it’s clear that obesity plays an important role in both sleep apnea and diabetes. Being overweight or obese is a primary risk factor for both conditions. Estimates suggest approximately 70 percent of people with OSA are obese, and 90 percent of people with diabetes are overweight or obese.
Here’s a quick review of OSA: Obstructive sleep apnea is a condition characterized by periods of decreased or interrupted breathing during sleep. In people with OSA, the airway becomes partially or fully blocked, temporarily cutting off airflow. OSA is harmful to both sleep quality and sleep quantity. People with OSA experience highly fragmented and restless sleep, awakening frequently because of their compromised breathing. They spend more time in the lighter stages of sleep, and less time in deep, restorative sleep stages. And they often sleep less overall. In addition to a higher risk for type 2 diabetes, people with OSA are also at greater risk for cardiovascular problems, including high blood pressure.
Scientists have yet to determine that OSA causes diabetes. But a growing body of evidence points to OSA as one possible cause.
- Research shows sleep fragmentation (aka restless or broken sleep) like that experienced by people with sleep apnea, decreases insulin sensitivity and glucose tolerance, and elevates levels of cortisol, a hormone that interferes with the ability of cells to use insulin effectively.
- The periodic interruptions in breathing (called hypoxia)—that can occur in OSA also decrease insulin sensitivity and glucose metabolism.
- Those interruptions in breathing have also been shown to have negative effects on the normal daily rhythms of blood glucose, and to damage the cells of the pancreas, which produces and releases insulin.
CPAP, or continuous positive airway pressure, is the primary treatment for OSA. CPAP is a small air compressor that blows air through a tube and a mask on your face while you sleep, to keep your airway open. Several studies have shown CPAP therapy can also improve insulin sensitivity in people with diabetes. The science is mixed here, but it does point to insulin and glucose-related benefits from CPAP in people who have severe OSA, and in people who use CPAP therapy very consistently. Getting patients to use CPAP routinely can be a problem, because let’s face it, who wants to sleep with a mask on their face?
It’s important for people with diabetes and prediabetes to be screened for OSA. Treating this sleep disorder may have significant benefits for controlling the disease, or for avoiding its development altogether. And people with OSA need to be aware of their increased risk for type 2 diabetes, and work with their physicians to address this risk.
Many people who have OSA don’t know they have it. The heightened risk for diabetes is another very good reason to pay attention for signs of disrupted breathing—snoring, gasping, and snorting—during sleep. If you (or your partner) shows these symptoms, or experiences excessive daytime tiredness, headaches, irritability and difficulty with concentration, talk with your doctor about being screened for sleep apnea.
Insomnia and other sleep disorders are also linked to diabetes
Insomnia is another sleep disorder associated with diabetes. I think we haven’t seen enough research looking specifically at the relationship between insomnia and diabetes.
Insomnia can include several types of sleep disruption, including:
- Trouble falling asleep
- Difficulty staying sleep
- Waking early
- Waking unrefreshed
You don’t have to have all these symptoms at once to have insomnia. People with insomnia typically don’t get enough sleep, and especially when insomnia is chronic, they often have irregular sleep cycles that signal underlying disruptions to circadian rhythms.
As we’ve seen, lack of sleep, poor quality sleep, and circadian disruptions all appear to interfere with metabolic function, decrease insulin’s effectiveness and glucose balance, and raise risks for type 2 diabetes.
Insomnia also occurs alongside diabetes, whether because of the underlying metabolic dysfunction or because of diabetes symptoms—or both. There is some evidence that medications used to treat diabetes, including the drug Metformin, can contribute to insomnia. Insomnia, like other sleep disorders, often goes un-diagnosed, including in people with diabetes. If you have diabetes or prediabetes, it’s important to talk with your doctor about your sleep patterns, and be assessed for insomnia.
Restless Leg Syndrome is a sleep and neurological disorder that involves uncomfortable tingling and crawling sensations in the legs that trigger intense urges to move the legs. These sensations happen more often and intensely in the evening, when relaxing or trying to sleep. RLS makes it hard to fall asleep, causes fragmented sleep, and often results in shortened sleep times and significant daytime fatigue.
People with diabetes may be at higher risk of developing RLS. Recent research indicates that RLS occurs significantly more often in people with diabetes than in the general population. The relationship between RLS and diabetes is not yet clear. The increased incidence of RLS in people with diabetes may be a result of nerve damage (neuropathy) that occurs with diabetes. It may also involve other factors, including poorly controlled blood sugar, cardiovascular disease, obesity, or vitamin and mineral deficiencies.
When sleep problems are more serious, diabetes tends to be more severe and less well controlled. Sleep affects so many elements that influence the development and course of the disease, from hormones to weight and eating habits, to mood, stress and immune function. Untreated sleep disorders can increase risk for diabetes—and they can also make the disease more complicated, serious, and difficult to treat.
People living with diabetes are more likely to experience disrupted sleep
Not everyone who has diabetes has trouble sleeping. But in my experience, most people with diabetes face pretty persistent challenges in sleeping well. They tend to struggle with a range of sleep problems, including:
- Trouble falling asleep and staying asleep
- Not sleeping enough
- Difficulty sleeping on a regular schedule, with consistent bedtimes and wake times
- A higher incidence of sleep disorders
Underlying causes of diabetes, including circadian rhythm dysfunction (disruptions to your biological clock) and the disruption of metabolic hormones, may contribute to these sleep troubles. But the symptoms of diabetes themselves can also result in fragmented, restless, unrefreshing and insufficient sleep. People with diabetes can experience a range of sleep-disrupting symptoms, including:
Frequent urination. This is a common symptom of hyperglycemia, or high blood sugar, that can occur during the day and at night. The need to urinate often at night is known as nocturnia. Needing to get up at night to use the bathroom causes fragmented sleep, reduces sleep amounts, and interrupts the natural flow of sleep through its individual stages and cycles.
Excessive thirst. Dehydration is a symptom of both hyperglycemia and hypoglycemia, or low blood sugar. Being thirsty and dehydrated can make it harder to fall asleep and cause you to wake repeatedly throughout the night.
Headaches. Both high and low blood sugar can cause headaches that make it hard to fall asleep and stay asleep.
Hunger. Hunger is another symptom of both high and low blood sugar. It’s difficult to fall asleep hungry. And eating heavily before bed also disrupts sleep.
Sweating. This sign of low blood sugar can prevent you from falling asleep. Sweating also can interrupt your sleep during the night.
Anxiety and Irritability. Low blood sugar can trigger anxiousness. Nighttime anxiety is a prime cause of insomnia and restless sleep. People with low blood sugar also may experience dizziness and heart palpitations—a racing or pounding heartbeat—that interfere with their ability to fall asleep.
Diabetic neuropathy. People with diabetes often suffer nerve damage. The most common form of diabetic neuropathy typically affects the feet and legs, and sometimes the hands and arms, creating pain, numbness, tingling, and extreme sensitivity to touch. Even the weight of a light blanket can trigger pain and discomfort. Different forms of neuropathy can have a wide range of effects on the body, including an inability to regulate body temperature, increased heart rate, and pain, that can make it hard to relax, get comfortable in bed, and sleep soundly.
Type 2 diabetes is most often thought of as a disease related to diet and exercise. There’s no question that poor diet and a sedentary lifestyle increase risk for diabetes. Even today, with all the evidence we have, sleep is overlooked as a risk factor. When assessing risk for developing diabetes, and when treating the disease, disordered sleep should be considered as seriously as a diet full of fatty, starchy and processed foods, or a lack of physical activity. If given the attention it deserves, sleep can be a powerful tool in helping avoid and improve diabetes.
Michael J. Breus, PhD, DABSM
The Sleep Doctor™
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