Sleep Apnea Severity Predicts Incident Diabetes 

Patients with obstructive sleep apnea are at higher risk for developing type 2 diabetes, and the proper treatment may lower the risk.  

Obstructive sleep apnea (OSA) is a common condition that causes a partial or complete block of your upper airway while sleeping. There are many complications related to obstructive sleep apnea such as cardiovascular and eye problems, sleepiness during the day, and metabolic disorders like type 2 diabetes. Previous evidence has proven that OSA is associated with insulin resistance, glucose intolerance, and type 2 diabetes independent of the confounding effects of obesity. Obesity is a common risk factor for both OSA and type 2 diabetes and also a significant contributor to insulin resistance. 

A longitudinal, community-based prospective study was conducted to measure the incidence of diabetes and obstructive sleep apnea. The participants in this study were from the Atherosclerosis Risk in Communities Study (ARIC) and the Sleep Heart Health Study (SHHS). The study population included a total of 1,453 participants gathered from the fourth visit of the ARIC study. An overnight unattended in-home polysomnogram was used to assess the sleep of each person. They were categorized by the apnea-hypopnea index (AHI), the number of obstructive sleep apnea and hypopneas per hour of sleep; hypopnea occurring with at least a 4% decrease in oxygen saturation while sleeping. The participants were categorized based on the AHI as follows: <5.0 events per hour (normal), 5.0–14.9 events per hour (mild), 15.0–29.9 events per hour (moderate), and ≥30.0 events per hour (severe). Only 5% of the participants in the ARIC study were classified as having OSA. Consequently, those who experienced average oxyhemoglobin saturation during non-rapid eye movement (non-REM) and REM sleep and those who had an average of 4% or greater oxygen desaturation events per hour of sleep (ODI) were used as variables to be similar to the definition of OSA. The participants from the ARIC study diagnosed by the physician and using diabetes medications were classified as having incident diabetes. 

As obesity is a significant risk factor for OSA, OSA prevalence is likely increasing with the increasing incidence of obesity. In conclusion, this study’s results provide strong evidence of OSA and incident diabetes’ relationship even after the data was restricted to participants with obesity. Two hundred eighty-five incident diabetes cases occurred, yielding a crude total diabetes incidence of 17.6 per 1000 person-years. Participants with severe OSA were at 2.75 times (95% CI: 1.81, 4.19) higher risk of incident diabetes than participants without OSA. The study’s findings provide supplementary information regarding the association from existing evidence with OSA and the possible risk of diabetes. 

Increasing OSA severity is associated with an increased likelihood of type 2 diabetes and worse diabetic control in patients with type 2 diabetes. Untreated sleep apnea perhaps causes an increase in glucose levels. According to the American Academy of Sleep Medicine, the more severe the untreated sleep apnea in a person with type 2 diabetes, the poorer their levels of glucose control. Some studies have shown possible therapy to improve OSA and control diabetes. A previous study examined 50 individuals with severe OSA and diabetes to see if continuous positive airway pressure (CPAP) could control their diabetes. Half of the patients received CPAP treatment, and the other half acted as a placebo, not receiving any treatment. Results from this study showed that measures of insulin resistance and sensitivity, as well as glucose tolerance, improved in the treated group. Another study was performed by Gagnadoux and his colleagues, establishing the relationship between an individual with OSA and the risk of developing type 2 diabetes. Four hundred ninety-seven people were already diagnosed with diabetes, and the remaining 265 were not diagnosed. There was more evidence on treating OSA in the patients that were not fully diagnosed but had a risk due to glucose tolerance. Potentially, there was better glucose control in these patients proving that treating OSA can improve glucose levels and insulin sensitivity. As a result, OSA treatment may help lower diabetes risk.  

Practice Pearls: 

• Obstructive sleep apnea is a risk factor related to type 2 diabetes. 
• The relationship between obstructive sleep apnea and incident diabetes is independent of obesity. 
• Obstructive sleep apnea was associated with the risk of developing type 2 diabetes, even when the participants involved were restricted due to having obesity (BMI≥30 kg/m2). 
• Treating obstructive sleep apnea with CPAP not only helps you sleep better but improves glucose levels as well.  

National Library of Medicine, Sept. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC5102826/#R18. 

Fessenden, Marissa. “The Link Between Sleep Apnea and Diabetes.” Advanced Sleep Medicine Services, Inc., December 8, 2016, www.sleepdr.com/the-sleep-blog/the-link-between-sleep-apnea-and- Nagayoshi, Mako, et al. “Obstructive Sleep Apnea and Incident Type 2 Diabetes.” Sleep Medicine, US diabetes. 

Kenya Henderson, 2021 PharmD. Candidate, Florida Agricultural & Mechanical University, College of Pharmacy and Pharmaceutical Sciences