IN PEOPLE WITH DIABETES, the hormone insulin, which removes excess sugar (i.e., glucose) from the blood, is produced in insufficient amounts (type 1 diabetes) or the body’s cells do not respond properly to the effects of insulin (type 2 diabetes).
The National Institute of Diabetes and Digestive and Kidney Diseases reports that approximately one in three diabetics who are age 40 or older have some signs of diabetic retinopathy, which is the most common cause of vision loss among diabetics.
Retinopathy (pronounced “RETin- OP-uh-thee”) is damage to the retina (pronounced “RET-in-uh”), a layer of light-sensitive cells that line the inner eyeball. The retina allows you to see in color and to see in dim light. In people with diabetes, retinopathy occurs because excess amounts of blood glucose cause swelling in the tissues of your eyes, which ultimately damages blood vessels in the retina. The damaged vessels swell, break apart, and leak fluid, thereby causing blurry vision. Sometimes new blood vessels grow, but they are fragile and contribute to further vision loss.
Symptoms of untreated retinopathy are spots or dark strings floating in your vision (i.e., floaters), blurred vision, fluctuating vision, dark or empty areas in your vision, and vision loss.
Some research indicates that obstructive sleep apnea (OSA) in people with diabetes may cause retinopathy to develop sooner. In addition, researchers have found that the number of individuals affected by retinopathy is higher among diabetics with OSA than among diabetics without OSA.
OSA is the intermittent cessation of breathing (i.e., apnea) during sleep that occurs because upper airway muscles that support tissues such as the tonsils, tongue, and adenoids relax excessively, which allows these tissues to fall into and block (i.e., obstruct) the airway during sleep. During the obstruction, a person continues to make respiratory movements but little or no air enters the lungs. The blood oxygen level consequently falls, which ultimately causes the person to arouse for a few seconds to take some deep breaths (during which time snoring occurs) and restore the blood oxygen level. Once the blood oxygen level is restored, the person falls promptly back to sleep, which can set the stage for another OSA episode.
For each OSA episode, the abrupt arousal followed by sleep causes a sudden increase and decrease in blood flow and blood pressure. Scientists believe that this process may damage already-fragile small blood vessels in the retina of people with diabetes, thereby increasing the risk of developing diabetic retinopathy.
Some research suggests that, for some people with diabetes, treating OSA may reduce the risk of developing diabetic retinopathy or may help slow the progression of diabetic retinopathy. However, the extent that treating OSA can prevent or slow the progression of retinopathy continues to be studied.
For now, scientists suggest that people with diabetes be assessed and treated for OSA because OSA is a risk factor for the development of diabetic retinopathy. You may want to consider having a sleep study if you are diabetic and you note the following symptoms of OSA: snoring, frequent arousals from sleep, daytime sleepiness, and other people witnessing you struggling to breathe during sleep. Regina Patrick, RPSGT, RST, is a freelance writer/editor and is a registered sleep technologist. She has been involved in the sleep field for more than 30 years.
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