Can Sleep Apnoea Cause Metabolic Dysfunction?

Obstructive sleep apnoea is becoming more of a common condition nowadays. This condition may also be associated with obesity. It may also be related to other diseases such as type 2 diabetes, the metabolic syndrome and non-alcoholic fatty liver disease. A recent review by Bonsignore et. al has tried to summarize the relationships between obstructive sleep apnoea and metabolic problems such as diabetes, obesity and metabolic syndrome.

We first go to diabetes and obstructive sleep apnoea. Are they related? If you take a closer look at these illnesses, you may find that these two illnesses have the same risk factors such as male sex, advancing age and obesity. It is said that about 30% of patients with obstructive sleep apnoea may also have concomitant type 2 diabetes. Similarly, many patients with type 2 diabetes may also have concomitant sleep apnoea. Some experts blame this on deteriorating insulin sensitivity in patients with sleep apnoea. Also, it should be noted that insulin resistance among patients with obstructive sleep apnoea was independent of oxygen desaturations at night.

Insulin resistance may be due to the increased sympathetic activation by intermittent hypoxia and sleep fragmentation found in sleep apnoea. Aside from sympathetic activation, factors include low-grade inflammation, activation of hypothamic-pituitary-adrenal axis and increased oxidative stress.

In some studies, it has been shown that continuous positive pressure (CPAP) treatment may have favourable effects on glucose metabolism and glycaemia control in patients with type 2 diabetes. In one particular study, it was shown that CPAP treatment did not reverse glucose intolerance or improve insulin sensitivity, except in patients with severe OSA.

With regards to metabolic syndrome and obesity, the risks may be related to inflammation in obese people. Fat tissues in obese people show increased macrophage infiltration with predominance of cells with a pro-inflammatory pattern of activation. Both obesity and sleep apnoea can bring about hypoxia in adipocytes. Also, it is to be noted that there is visceral fat accumulation among patients with obstructive sleep apnoea. Visceral fat accumulation is one of the features of metabolic syndrome. It is said that patients who have more severe sleep apnoea have a significantly higher metabolic index compared to patients with mild-to-moderate sleep apnoea. Visceral fat may be evident on increased neck circumference among patients with obstructive sleep apnoea.

Aside from this, there is a relationship between liver disease and obstructive sleep apnoea. It is said that obstructive sleep apnoea may worsen liver damage and dysfunction in obese patients by promoting the shift from simple steatosis to non-alcoholic steatohepatitis (NASH). Chronic intermittent hypoxia may be responsible for this problem.

If you want to stop snoring and prevent sleep apnoea from occurring, you should start with losing weight. Obesity is the most important major modifiable risk factor associated with OSA. Even a 10% weight loss can decrease risk for obstructive sleep apnoea by 26%. Weight loss can be achieved by physical activity. Conservative weight loss approaches included an assortment of cognitive behavioural therapy and dietary prescription, sleep hygiene, home diets and self-managed exercise. All these are helpful in preventing metabolic syndrome and obstructive sleep apnoea.

Reference:

Bonsignore MR1, Borel AL, Machan E, Grunstein R. Sleep apnoea and metabolic dysfunction. Eur Respir Rev. 2013 Sep 1; 22(129):353-64.

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