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Sleep Apnoea and Type 2 Diabetes
Recent research demonstrates the likelihood of a relationship between type 2 diabetes and sleep-disordered breathing (SDB), in particular obstructive sleep apnoea (OSA), the most common form of SDB.

Links between diabetes and micro and macro vascular complications such as cardiovascular disease (CVD), nephropathy (kidney disease), retinopathy (eye disease) and neuropathy (nerve disease) are now well established and represent a huge burden to the individual and society.

In recent years studies have demonstrated that diabetes is likely to be associated with other problems and conditions which all add to the burden. They include disability, impaired cognitive function, reduced quality of life and sleeping disorders.

The IDF consensus statement on sleep apnoea and type 2 diabetes wants to raise awareness of the association between sleep apnoea and type 2 diabetes. IDF calls on health decision makers to encourage further research into the links between the two conditions and urges healthcare professionals to adopt new clinical practices to ensure that a person with one condition is considered for the other.

Facts:
•  Type 2 diabetes and OSA are likely to be linked.
• Overweight and obesity may play a role, but some recent studies show an association between the two conditions that is independent of overweight/ obesity.
• OSA may have effects on glycaemic control in people with type 2 diabetes.
• OSA is associated with a range of cardiovascular complications such as hypertension, stroke and heart failure.

IDF recommendations to healthcare professionals
• 

Healthcare professionals working in both type 2 diabetes and OSA need to be aware, educated and trained about the link between both conditions. They should aim to develop routine interventions that are appropriate for both conditions.
•

People with OSA should be routinely screened for possible metabolic disorders and cardiovascular risk. Screening tests are inexpensive and easy to conduct, and include measurement of

- Waist circumference
- Blood pressure
- Fasting lipids
- Fasting glucose
•

Screening people with type 2 diabetes for OSA is more complex, however they should be screened particularly when they present with classical symptoms such as witnessed apnoeas, heavy snoring or daytime sleepiness. One screening strategy uses a two-stage approach in which a structured questionnaire (e.g. the Berlin questionnaire) is used in the first stage to assess the pre-test probability of sleep apnoea. Those identified to be at high risk for OSA undergo a second stage, with an overnight evaluation at home with pulse oximetry or portable monitoring.
• Management of OSA includes:
-  Weight reduction for the overweight and obese. Losing weight should be the primary treatment strategy as it may improve energy, social interaction and work performance and reduce accidents. Additionally, reduction of daytime sleepiness may encourage physical activity, which will have positive effects on glucose metabolism and on keeping a healthy body weight.
- Continuous Positive Airway Pressure (CPAP) treatment. This therapy is currently the best treatment for moderate to severe OSA and should be considered where appropriate. CPAP treatment has been shown to have a positive impact particularly in people who have CVD.

IDF Recommendations for further research include:
•  Conduct epidemiological studies of the prevalence of OSA (also in people with type 2 diabetes and metabolic syndrome, in children with obesity and/or type 2 diabetes, different ethnic groups and gestational diabetes and pre-eclampsia).
• Evaluate the effects of OSA on insulin secretion, insulin resistance and complications of type 2 diabetes.
• Implement intervention studies that analyse the effects of various therapies for OSA in people with diabetes, particularly focusing on cardiovascular outcomes, and the mechanism linking sleep apnoea with diabetes.
• Further develop resources for effective diagnosis and treatment of OSA in all settings.

Research Studies:

Recent research in the fields of diabetes and sleep apnoea demonstrate the likelihood that a relationship exists between type 2 diabetes and sleep-disordered breathing. Excerpts from key studies referenced in the consensus statement are listed below:
•  According to findings from the Sleep Heart Health Study:
-  More than half of people with type 2 diabetes have some form of sleep disorder, with up to a third of those affected by obstructive sleep apnoea (OSA).
- Sleep disturbances in people with diabetes can be as prevalent as 58 percent.
• As reported in studies published in European Respiratory Journal in 2003 and Journal of Internal Medicine in 2001 , up to 40 percent of people with OSA will have diabetes.
-  The European Respiratory Journal study also suggests that those with mild OSA were significantly more likely to have impaired glucose tolerance and diabetes than those without OSA.
- Additional glucose-insulin studies indicate that intermittent shortage of oxygen in the body, and/or the sleep fragmentation , that result from OSA cause a physiologic stress which can have an impact on glucose metabolism and can play an important role in the development of insulin resistance.
• Evidence from three separate studies suggests:
-  The association between type 2 diabetes, insulin resistance, metabolic syndrome and OSA is not totally dependent on obesity.
- The prevalence of OSA in people with diabetes can be up to 23 percent.
- The prevalence of some form of SDB in people with diabetes can be up to 58 percent.
• Two studies of metabolic syndrome suggest that individuals with OSA demonstrated signs of metabolic syndrome and conversely those with metabolic syndrome showed an increased risk of OSA.

In people with diabetes, the impact of CPAP treatment on the improvements in insulin sensitivity has been mixed, however some studies have shown a significant reduction in A1C levels in people who had less optimal control.
Source: International Diabetes Federation 2009
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