Sleep apnea is characterized by one or more pauses in breathing or instances of shallow breathing while asleep. It is a chronic condition that can disrupt sleep. It often escapes detection and diagnosis because sleep sufferers rarely know they have it and its signs don’t show up on routine visits to the doctor’s office. Often a person’s bed partner is the first one to notice it because the person with sleep apnea is snoring.
There are two main types of sleep apnea — obstructive sleep apnea and central sleep apnea. In obstructive sleep apnea, the airway collapses or becomes blocked during sleep, causing shallow breathing or breathing pauses. It is more common in people who are overweight.
Central sleep apnea, which is less common than obstructive sleep apnea, occurs when the area of the brain that controls breathing fails to send the proper signals to the person’s breathing muscles. As a result, the person stops breathing for brief periods.
A number of factors can predispose a person to sleep apnea. For example, in some people, the tongue and tonsils are large compared with the opening of the windpipe, making it easier for the windpipe to become partially or completely blocked. Being overweight is also a risk factor for obstructive sleep apnea because extra soft fat tissue can thicken the wall of the windpipe, making it narrower.
Sleep apnea in turn can be harmful to a person’s health. The frequent drops in blood oxygen level can trigger the release of stress hormones. These hormones raise a person’s heart rate and increase the risk of high blood pressure, heart attack, stroke and cardiac arrhythmia (irregular heartbeat). They can also affect blood glucose metabolism, setting the stage for obesity and Type 2 diabetes.
Several studies have indicated that obstructive sleep apnea is a strong risk factor for Type 2 diabetes. Other studies have shown a compelling association between the severity of obstructive sleep apnea and hemoglobin A1C (HbA1c) levels, a measure of average blood glucose level over time. Furthermore, a recent study showed that sleep apnea is associated with the development and progression of diabetic retinopathy (retinal disease associated with diabetes) in people with Type 2 diabetes. Conversely, some evidence indicates that diabetes may be a risk factor for certain types of breathing disorders. Some researchers have hypothesized that diabetic autonomic neuropathy (diabetes-related disease of the autonomic nervous system) contributes to central sleep apnea.
Doctors diagnose sleep apnea based on medical and family history and, if warranted, a sleep study. A sleep study is usually performed using a polysomnogram (PSG) or a home-based portable monitor. PSG records brain activity, eye movements, heart rate and blood pressure. It also records the amount of oxygen in the patient’s blood, the movement of air through the patient’s nose while he or she breathes, snoring, and chest movements.
In some cases, the doctor recommends a home-based test using a portable monitor. The portable monitor records some of the same information as a PSG, such as the amount of oxygen in the blood, air movement through the nose while breathing, heart rate, and chest movement.
There are several ways to treat sleep apnea. For mild sleep apnea, certain lifestyle changes may work, such as:
• avoiding alcohol and medications that cause drowsiness;
• sleeping on one’s side instead of one’s back to keep airways open;
• treating any nasal congestion with nasal sprays or allergy medicines;
• quitting smoking; and
• wearing a mouthpiece called an oral appliance to keep the airway open.
Continuous positive airway pressure (CPAP) is the most common treatment for moderate to severe sleep apnea. The CPAP device utilizes a mask that fits over the patient’s mouth and nose — or just the nose — and blows air into the throat. The air pressure keeps the patient’s airway open during sleep.
In some patients, surgery may help to widen breathing passages. Generally, surgery involves shrinking, stiffening, or removing excess tissue in the mouth and throat and resetting the lower jaw.
If sleep apnea contributes to diabetes, could treating it help prevent diabetes and improve blood glucose control in people who have diabetes? Preliminary evidence suggests that it can. Early studies failed to show a strong effect, but in those studies, many patients failed to adhere to their CPAP regimen. In a recent study reported in Journal of Clinical Sleep Medicine, those patients with obstructive sleep apnea who stuck with CPAP had lower rates of impaired fasting glucose, prediabetes, and Type 2 diabetes.