Many studies have assessed how untreated sleep apnea affects insulin resistance, which often precedes diabetes. Unfortunately, likely due to different study designs, results have been mixed, leaving a somewhat cloudy relationship between insulin resistance and sleep apnea. Inconclusive results may have been due a small number of study participants. In cases like this, it is often helpful to do a large, combinatory study that creates one large study population from many similar smaller studies.
Recently, a group of researchers pooled together 5 studies on how sleep apnea affects insulin resistance, creating a sample of 244 subjects. Importantly, none of these subjects suffered from diabetes. Because diabetes often complicates the situation (because injections of insulin are usually involved), the researchers specifically excluded this group to examine endogenous levels of insulin. In addition, insulin resistance was measured in two groups of subjects – those treated with sleep apnea treatment (CPAP) and those on sham CPAP, which is basically the placebo pill equivalent of CPAP. This group is necessary to serve as a control group.
After comparing groups, results showed that CPAP treatment did indeed have an affect on lowering insulin resistance (which is a good thing) in this group of 244 subjects without diabetes1.
Being able to join together multiple studies is ideal, albeit rare because of dissimilar study designs, because it allows for the creation of one large subject population. Typically, the more subjects, the more trusted the results. Because this study was able to incorporate a large number of subjects, we can now begin to clear away some of the cloudiness of the relationship between sleep apnea and insulin resistance. Isn’t it magical what a little faithful CPAP treatment can do to one’s health?
1. Iftikhar IH, Khan MF, Das A, Magalang UJ. Meta-analysis: continuous positive airway pressure improves insulin resistance in patients with sleep apnea without diabetes. Ann Am Thorac Soc. 2013 Apr;10(2):115-20. doi: 10.1513/AnnalsATS.201209-081OC. Review.