Of all the sleep disorders, sleep apnea is most common, affecting almost 80% of all diagnosed patients. On the other hand, diabetes, a kind of disorder affecting the body’s metabolism, is currently affecting a total of 25.8 million people in America, including of children. Of these, only 18.8 million are diagnosed and between 90 and 95% suffer from diabetes type 2.
In terms of age-wise prevalence, the highest risk group is 20 years and above (25.6 million or 11.3% of people of this age) followed by people who are 65 years of age or older (10.9 million or 26.9% of people in this age bracket). While 11.8% of all men above the age of 20 have diabetes, 10.8% of women in this age group have this ailment.
Before we elaborate further on how sleep apnea and diabetes are linked and how the conditions can be managed simultaneously, let us get a clear idea of what diabetes is. Most people know it as having ‘excess sugar in the blood’. Is that all or there is more to it? Do diabetes and sleep have any links? Let us find out.
You have diabetes when there is excess glucose (sugar) in your blood. Though presence of glucose is mandatory for producing energy, too much of it can be risky for your health. But how does the body get glucose? It essentially comes from the foods you eat. The liver and pancreas also produce glucose.
The reason why diabetes is called a disorder affecting metabolism is because it is involved with the way the body utilizes the glucose in the blood for the purposes of getting energy and achieving growth. The process starts with digested foods forming glucose which goes into the blood for further use by the cells.
However, to enable glucose penetrate into the cells, a type of hormone is necessary, called insulin, produced by a gland called pancreas. Insulin is an important hormone with many important tasks to do. Other than helping the cells to use glucose, insulin also helps in the storage of extra energy in muscles, liver and fat tissues. The pancreas responds automatically by producing requisite amounts of insulin, as soon as digestion is complete and it is time for the cells to use the glucose.
But a situation might happen, like in diabetes, where the pancreas is incapable of producing the requisite amount of insulin. It could also be that cells cannot use the insulin the way it should. Either way, this raises the glucose levels in the blood. The excess glucose subsequently gets out of the body through urine. The net effect of such events is that though the body has enough glucose for energy, it is unable to use it and ends up losing it.
High levels of glucose in the blood harm many body parts like the eyes (vision loss), kidneys, heart, nerves, blood vessels, gums, etc.
There are three main types of this condition including gestational, type 2 and 1. Of the three types, type 2 is most common. It is mostly associated with advancing age, stress, hereditary factors, obesity, sedentary lifestyle, history of diabetes during pregnancy, etc. One of the most important triggers for developing diabetes type 2 is obesity.
Insulin resistance is a condition which is an outcome of this type of diabetes. It happens when the body is no longer able to make use of the insulin produced by the pancreas. The onset of the condition is never sudden; it could take years before the body becomes incapacitated to make efficient use of insulin, though in the initial phases the pancreas puts in extra effort for producing more insulin.
An individual can develop diabetes type 2 any time in life, even as a child. Some of the typical symptoms of this type of diabetes include excessive hunger and thirst, tiredness, frequent need for urination, sores and wounds taking a long time to heal, vision becoming blurred, etc. Some individuals may not show any symptoms of the disease though.
The point where type 1 differs from type 2 is that in the former condition, body is completely unable to produce insulin; on the other hand, in type 2, the body cannot make use of whatever quantity of insulin is produced. The commonality between the two is that the outcomes are same: excess glucose content in the blood.
Common terminologies used in diabetes management
It makes sense to understand the meaning of certain common terms used by doctors (and patients as well) during diagnosis and treatment of diabetes. Some of them are: pre-diabetes, fasting glucose, glucose intolerance, etc.
When an individual shows high levels of blood glucose but the level is not alarming enough to qualify as being diagnosed as diabetes, the condition is termed as pre-diabetes. This condition is gradually becoming a health menace as confirmed by the U.S. Department of Health and Human Services. According to their 2007 estimate, close to 57 million American adults are victims of pre-diabetes, who have high chances of developing diabetes in the next decade.
Impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) are two other terms to describe pre-diabetes and used according to the specific diagnostic measures used. For example, when the fasting glucose level is between 100 and 125 mg/dL, considered higher than normal but not elevated enough to be termed as diabetes, the condition is called IFG. Likewise, after two hours of having an oral glucose tolerance test (OGTT) , if the blood sugar level is between 140 and 199 mg/dL, still not considered to be elevated enough to be termed as diabetes the term used to describe the condition is IGT.
Sleep apnea and diabetes
Discussing the origin of these two co-existing health conditions like diabetes and sleep apnea, explaining the rationale of their link, etc before we talk about the impact sleep has on diabetes, would be like putting the cart before the horse. Let us begin at the beginning: diabetes and sleep.
Poor or fragmented sleep, interruptions during sleep, etc are known to cause many health disorders. A recent study reveals that inadequate sleep which upsets the biological system of the body can result in diabetes as well as obesity. The report was published online in Science Translational Medicine in April this year.
Involving 21 participants who were otherwise healthy, the study stretched over a long period of time and included changing sleep time, imitating jet lag, sleep alterations due to change in work shifts, etc. The results showed that restricted sleep for a long period of time not only lowered resting rate of metabolism but also raised blood glucose levels due to inadequate production of insulin. Lowered rate of metabolism could contribute to weight gain. Rise in glucose levels combined with insufficient secretion of insulin can set the stage right for the onset of diabetes.
On the other hand, diabetics usually have troublesome sleep patterns including problems to fall and remain asleep. It is also possible that some diabetics sleep for too long and some may not get adequate sleep at all. Several reasons can be attributed as to why diabetics have problems with sleep. They can be suffering from many types of co-existent health conditions like restless legs syndrome, sleep apnea, painful illnesses, etc.
Obesity and blood sugar levels (high or low) also impact sleep in diabetics. For example, obese people run the risk of developing associated problems like snoring, heart problems, stroke, hypertension as well as sleep apnea. Lowering of blood sugar levels (also called hypoglycemia) happen due to not having food for a long time, or having medications that shoot up insulin levels. High sugar levels, medically called hyperglycemia can happen due to excess calorie consumption, skipping medicines or as an effect of another ailment. Even stress caused by emotional factors can cause hyperglycemia. Both these extremes can upset sleep.
Poor sleep quality results in an increased risk of gaining weight, which is a pre-cursor for diabetes. Major deprivation from sleep affects two appetite-related hormones, Leptin and Ghrelin. Lowering of Leptin has been associated with an individual’s craving for carbohydrates no matter how much calories have been consumed.
When sleep problems become chronic, it results in insulin resistance, a condition described earlier which often lead to diabetes.
Sleep apnea and diabetes: the situation in the US
Close association between the two conditions, undoubtedly has grave implications on the health of people in this country. The following statistics can be alarming:
- 40% of apnea patients have diabetes.
- 36% of patients with concurrent apnea and diabetes have AHI more than 15.
- 23% of diabetics can also be suffering from sleep apnea and 58% could be affected by some type of sleep disorder.
- Though obesity has a role to play in the onset of these conditions, recent studies show that the two conditions can exist, even when the patient is not obese
- Sleep apnea may negatively affect controlling diabetes type 2.
- Severity of apnea is directly proportional to rising levels of glucose intolerance and insulin resistance.
How the relationship begins
In a comprehensive review of literature pertaining to 83 clinical studies done on this topic, it was found that of all the several types of sleep disorders, the association of diabetes with sleep apnea was strongest. The relationship can originate in multiple ways: sleep interruptions caused by recurrent hypopxemia of sleep apnea triggers glucose imbalance; gradually, such anomalies trigger increase of body weight, which is also responsible for increasing the seriousness of sleep apnea.7
Even after discounting the typical triggers for sleep apnea, like advancing age, obesity, girth measurement and sex, it is found to be associated 7,9 with IFG, IGT as well as diabetes type 2. 86% of patients identified as obese who were affected by diabetes also had undiagnosed sleep apnea. This was revealed in the Sleep AHEAD study. Studies have also shown that undiagnosed sleep apnea can aggravate diabetic conditions and make treatment more difficult.
According to findings entitled “Obstructive Sleep Apnea as Risk Factor for Type II Diabetes” presented in May 2007, during the American Thoracic Society International Conference, it was shown that chances of apnea patients developing diabetes type 2 were higher and was not related to other factors that increased the risk. The study, involving 593 patients and took almost 6 years to complete found that the risk increased by almost 2.5 times.
While it is still unclear how the link gets established, but researchers believe that the fight-or-flight responses triggered by apnea events could hike up the secretion of cortisol hormone which eventually results in insulin resistance and glucose intolerance, both of which are conditions related to pre-diabetes. When such conditions are not treated on time, diabetes is inevitable. Lowering of oxygen content in blood also seems to play an important role in the events.
It is important to note that both these conditions have one common risk factor and that is obesity. Sleep apnea typically results in oxygen depletion which could cause metabolic imbalance. This could cause excessive secretion of adrenalin, which could further deteriorate insulin resistance and thus become responsible for accelerating onset of diabetes.
Research has also shown that sleep apnea left untreated can lead to diabetes and several other major consequences.
Management of sleep apnea and diabetes: begins with treating the sleep disorder
The first aspect that we need to keep in mind regarding management of the twin conditions is that sleep apnea can impact blood sugar control in more ways than one. Repeated arousals from sleep result in prompt release of stress hormones that make the patient stressed and lethargic with no motivation whatsoever to do any kind of physical exercise, etc. Be that as it may, it is also true that treatment of sleep apnea stabilizes blood glucose levels, impacts insulin resistance positively and increases patient motivation as well as alertness.
Therefore doctors recommend that if an individual has been diagnosed with diabetes type 2 and at the same time, experiences some of the tell-tale symptoms of sleep apnea like excessive daytime tiredness, etc, it is wise to get a diagnosis for sleep apnea without any delay. The 2008 consensus statement issued by the International Diabetes Federation (IDF) mentions two treatment modules that are deemed most suitable for managing the twin conditions: a) weight loss for patients who are obese; and 2) CPAP therapy for apnea patients who have mild to moderate severity.
In the Sleep AHEAD study, it was found that a weight loss of 22 pounds resulted in major improvements of apnea symptoms and in some patients, the symptoms were completely eradicated. According to IDF, CPAP is acknowledged as the best therapeutic option for the management of sleep apnea. Though some patients might find this option uncomfortable, patience during use can go a long way in providing lasting relief.
Control of insulin sensitivity (leading to effective control of blood sugar levels) is one of the primary goals of diabetes management. One study demonstrated that within 48 hours of deploying CPAP therapy, there was significant improvement in this critical aspect. Thus the researchers concluded that long-term use of this therapy option can be a viable treatment option for managing diabetes as well.
After using CPAP for about 4 hours every night for a period of 3 months at a stretch, was able to reduce blood sugar levels from 191 mg/dL to 130 mg/dL (after breakfast) and similar lowering of levels was witnessed after other meals during the day. Therefore if a diabetic patient shows symptoms like persistent snoring, daytime tiredness, etc should get checked for sleep apnea and if the results are positive, should first treat the sleep problem. It is certain to impact diabetic conditions positively as well.
Sleep apnea is capable of worsening diabetic condition further according to University of Chicago researchers. Ex-president of American Thoracic Society emphasizes on the importance of screening diabetic patients for sleep apnea as a majority of diabetics are most likely to have sleep apnea as well. Proper treatment of their breathing distress is certain to improve their high blood sugar levels simultaneously as well as help in the prevention from long term adverse effects of diabetes. Enjoying a good nights’ sleep, he says, is bound to have a positive impact on diabetic symptoms.
While it is not yet known whether use of CPAP therapy has any curative effect on diabetes but the therapy can definitely ensure pause-free breathing during sleep, which ultimately improves the apnea condition for the diabetic patient. This improves quality of life by significantly reducing daytime lethargy.
Losing weight can have a positive impact on pre-diabetes in terms of glucose control17 as well. To reduce the risk of pre-diabetes progressing towards diabetes, research has proved that even a 5 to 7% weight loss with the help of diet and physical exercises can minimize diabetes risk by almost 60%. Doctors recommend cutting down on calories and walking for about half an hour every day for 5 days in the week.
It is now clear that not only are sleep apnea and diabetes share close links, obesity is a common cause that can trigger both. It has been said that so long as obesity increases in the general population, instances of diabetes along with sleep apnea would continue to increase as well. Thus it is imperative that every diabetic patient be screened and diagnosed for sleep apnea, especially if he or she is overweight, and displays some of the characteristic signs of apnea.