The Connection between Sleep Apnea and Diabetes

There are hundreds of scientific studies concerning sleep apnea and diabetes.  The sheer number is surprising since most sources do not mention a connection between the two conditions.

The symptoms of sleep apnea according to the Mayo Clinic are excessive daytime sleepiness, loud snoring, waking often or suddenly with a feeling of being short of breath, dry mouth or headache in the morning and periods of missed breaths or breathing cessation while sleeping, often between snores.  The latter is typically reported by a parent, roommate or bed partner.

The symptoms of diabetes include extreme thirst or hunger, shakiness, irritability, blood sugar levels that are abnormally high or abnormally low and frequent urination.  As you can see, there are no similarities between the symptoms of the two conditions.

The cause of sleep apnea is either an obstruction of the airways or failure in the brain to respond to blood gas changes and send a signal to breathe.  The cause determines the classification or type. 
The type caused by an obstruction is classified as obstructive sleep apnea or OSA.  The type cause by the brain’s failure to respond to changing blood gas levels is classified as “central” sleep apnea or CSA, because the “central” nervous system is involved.  There is a third mixed type in which both obstructions are present and the central nervous system is involved.

There are several types of diabetes.  Type I or juvenile diabetes is caused by failure of the insulin-producing pancreatic beta cells.  It is also referred to as insulin-dependent.

The cause of type II or the adult onset type has been difficult to identify. The latest research indicates that in most cases, it is a lifestyle disease, related to diet, physical inactivity and being overweight or obese.

A third type is gestational diabetes.  It occurs only in pregnant women.  The causes are unclear, but it seems that a healthy diet and limiting weight gain during pregnancy help prevent it.

As you can see, there are no similarities between the causes of sleep apnea and diabetes.  It is the complications and the risk factors of sleep apnea and type II or adult-onset diabetes that are similar. 
There seems to be a genetic factor in both conditions.  Having a family member with either health problem increases your risk of developing the condition.

Being overweight or obese increases your risk of developing both health problems.  Fat deposits around the neck or a large stomach that makes it difficult to breathe at night can lead to OSA.
Not everyone who is overweight or obese has abnormal blood sugar levels.  A lot has to do with what the person chooses to eat.  Foods with a high glycemic index, primarily simple carbohydrates, contribute to the condition by causing erratic spikes in blood sugar levels.

People with heart disease are more likely to suffer from apneas. Heart disease is often a complication of type II diabetes.  High blood pressure often accompanies sleep apnea and diabetes.  Uncontrolled high blood pressure increases a person’s risk of developing heart disease.

So, there are some similarities.  The studies concerning the connection began because doctors were seeing many patients with both sleep apnea and diabetes type II. 

In one of the recent studies, researchers found that OSA is associated with changes in the body’s ability to maintain blood sugar levels.  They found that in severely obese adults with OSA, there was an increase in blood insulin levels.

One of the things that happen in type II diabetes is that the cells of the body become resistant to insulin.  Insulin is a signaling hormone.  Its primary function is to signal the cells of the body to take in glucose from the bloodstream and use the glucose for energy.

When the cells become resistant to insulin or fail to recognize the signal, glucose builds up in the bloodstream.  The insulin also remains in the bloodstream. 

The glucose can bind with proteins and form grotesque molecules called advanced glycation end-products or AGEs.  The insulin has inflammatory activity.  Both AGEs and inflammation are a cause of cellular aging.  They contribute to heart disease, cancer, Alzheimer’s and other life threatening diseases.

One of the things that researchers look for when investigating the connection between sleep apnea and diabetes is the presence of inflammatory molecules in the bloodstream.  Not only do high blood sugar and insulin levels lead to increased inflammation throughout the body.  Increased inflammation plays a role in the body’s ability to regulate blood sugar levels.  So, it is something of a vicious circle.
Another thing that sometimes happens in type II diabetes is that the pancreatic beta cells stop functioning normally.  They fail to produce enough insulin to keep blood sugar levels stable.

Some studies have shown that in OSA, the pancreatic beta cells are stimulated during the low blood oxygen levels that occur when breathing stops during the night.  In that case, there is no reason for insulin to be produced. 

Since the episodes of breathing cessation may be as high as 12 per hour, the beta cells may be stimulated to produce insulin excessively throughout the night.  This could lead to exhaustion of the insulin-producing cells, which in turn could lead to type II diabetes or increased severity of the disease.
The findings in these most recent studies show that the changes in blood sugar levels are not due solely to diet or to the existence of type II diabetes.  The researchers believe that OSA may play a causative role in the disease, especially if the patient is already in a pre-diabetic state with borderline high blood glucose levels.

So far, no link has been established between CSA and diabetics. Only people with OSA, which is more common, were included in the most recent studies.  However, if OSA causes problems in blood sugar maintenance, because of low blood oxygen levels, then CSA would cause the same problems.
The conclusion made by researchers in one of the sleep apnea and diabetes studies was that treating OSA or CSA could reduce the overweight or obese individual’s risk of developing diabetes and the complications associated with it.  If you have either problem, see your doctor and get treatment.