15 Mar CPAP Benefits Sleep and Blood Pressure in Diabetics, But Not Glucose Control
MedicalResearch.com Interview with:
Jonathan Shaw MD, FRACP, FRCP (UK), FAAHMS
Domain Head, Population Health Research
Baker IDI Heart and Diabetes Institute
Melbourne VIC 3004
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Shaw: Over the last decade or so, there has been a lot of research connecting obstructive sleep apnoea with type 2 diabetes. They co-exist very frequently in the same individual, they are both much more common in overweight and obese people than in people of healthy weights, both improve with weight loss, and both are associated with other conditions such as hypertension and heart disease. In addition, there has been evidence that some of the key abnormalities occurring in sleep apnoea (in particular, fragmented sleep and intermittent low oxygen levels) may have a direct effect on glucose metabolism, and increase blood sugar levels. This led many people to suspect that untreated sleep apnoea might be one reason that type 2 diabetes is hard to control, and that treating sleep apnoea in people with type 2 diabetes would improve their blood sugar control.
We, therefore, undertook a large trial among people with type 2 diabetes, and previously unrecognised sleep apnoea, in which participants were randomised to either a group receiving specific treatment for sleep apnoea (continuous positive airways pressure, or CPAP, therapy at night) or to a control group.
Over the six months of the trial, we saw no benefit of CPAP therapy in regard to blood sugar control (as measured by HbA1c). Even when we looked at sub-groups with worse blood sugar control at the start or worse sleep apnoea or who did the best in terms of using CPAP every night, there was still no sign of benefit on blood sugar control. We did, however, see some other benefits of CPAP therapy, with less daytime sleepiness, improvements in quality of life and lower diastolic blood pressure.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Shaw: Our study confirms what has been shown in other studies – that CPAP therapy helps people to feel less sleepy, improves their quality of life and can help with controlling blood pressure. It is, therefore, a valuable treatment for sleep apnoea in people with type 2 diabetes, among whom it is very common. However, it should not be expected to improve blood sugar control, and therefore there is no justification from our study to start to screen for sleep apnoea in people with type 2 diabetes, unless they have symptoms that suggest it might be there, and that might improve if treatment is commenced.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Shaw: Whilst we saw no benefit for blood sugar control in the general diabetic population, there are at least three avenues that need further exploration. First, since we excluded people with very poorly controlled diabetes, and on insulin, this could be a group whose blood sugar control might benefit from CPAP. Second, some evidence suggests that the role of sleep apnoea in relation to diabetes is stronger before diabetes has developed than once it is established. Thus, it is possible that in people at risk of developing diabetes, who also have sleep apnoea, treating the sleep apnoea might reduce the chances of subsequently developing diabetes. Finally, many people find it hard to use the CPAP therapy all night every night, and further research might be able to show that much higher usage rates than we were able to achieve are needed to show benefits for blood sugar control.
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Am J Respir Crit Care Med. First published online 29 Feb 2016 as DOI: 10.1164/rccm.201511-2260OC
The Effect of Treatment of Obstructive Sleep Apnea on Glycemic Control in Type 2 Diabetes
Jonathan E Shaw, Naresh M Punjabi, Matthew T. Naughton, Leslee Willes, Richard M Bergenstal, Peter A. Cistulli, Greg R Fulcher, Glenn N Richards, and Paul Z Zimmet
Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.
Jonathan Shaw MD (2016). CPAP Benefits Sleep and Blood Pressure in Diabetics, But Not Glucose Control MedicalResearch.com