Obstructive sleep apnea (OSA) is a sneaky disease affecting 22 to 25 million American adults. These figures are uncertain as it’s thought that the majority of sufferers – up to 80% of patients with moderate to severe cases – are actually unaware that they have OSA (hence its sneaky nature). This is partially due to lack of knowledge about this disease but also because the only way to definitively diagnose OSA is with a sleep study, which requires significant resources. The American Journal of Epidemiology reports a significant increase in the prevalence of OSA over the last 20 years, thought to be due to the link between OSA and obesity. During sleep, the upper airway becomes blocked from a collapse of the anatomy around the throat, resulting in recurrent moments of apnea, which basically means you stop breathing. Now, because we all know that oxygen is important for survival, it should come as no surprise that taking in significantly reduced amounts of it over several hours every night can lead to some problems.

The Bidirectional Relationship Between Obesity and OSA
The bidirectional relationship between obesity and OSA is well accepted – obesity and weight gain are considered to be the strongest risk factors for the development and progression of OSA, and the presence of OSA is also a contributor to rapid weight gain, plunging the luckless subject into what might be termed a vicious cycle. The presence of OSA in obese patients is thought to be as high as 45%, around double that of the general population, while the percentage of excessive weight/obesity in patients with OSA is around 70%. This vicious cycle is complex and not fully understood in its entirety, but might involve something like this: increasing weight and fat deposition in the structures around the upper airway can increase its likelihood to collapse during sleep and induce apnea; poor sleep quality and excessive daytime sleepiness from OSA can lead to lethargy, reduced physical activity, and altered eating patterns, which, in turn, contribute to weight gain and obesity.

Weight loss is thought to be an effective concurrent therapy for reducing the severity of OSA but alone does not eliminate OSA entirely for all patients, who will still be recommended to use a CPAP (continuous positive airway pressure) machine. In theory, improving sleep quality by reducing overnight apnea events with a CPAP machine can help to increase energy levels during the day, perhaps to a point where the patient may be energized enough to jump out of the vicious obesity-OSA cycle and go for a real cycle instead, encouraging further weight loss.

The Exclusive Relationship Between Diabetes and OSA
OSA appears to be good friends with diabetes, with studies showing up to 30% of OSA patients having type 2 diabetes and a huge 86% of obese diabetic patients having OSA, with the severity of OSA linked to poor diabetic control. Moderate to severe OSA has been shown to increase the risk of developing type 2 diabetes, although this association was not found with mild OSA cases. It is thought the effects of OSA impact insulin resistance and dysfunction of insulin production by the pancreas, leading to insulin-dependent (type 2) diabetes. The effects of diabetes on OSA is less well understood but hypothesized that weight gain associated with diabetes contributes to the development of OSA or exacerbation of existing OSA. A large confounding factor while investigating the exclusive relationship between diabetes and OSA is the fact that obesity is often quite friendly with both diabetes and OSA, making a sort of blurry love triangle. Nonetheless, because of the strong associations, the International Diabetes Foundation recommends screening for OSA in high-risk diabetic patients.

Although blood sugar control does not seem to improve with the treatment of OSA with CPAP, failing to treat OSA at all is associated with an increased problem with diabetic complications, including diabetic eye disease, kidney disease, and neuropathy.

The evidence associating obstructive sleep apnea with both obesity and diabetes is weighty, supporting concurrent management with CPAP and weight loss/good diabetic control in affected patients.

Next month  we discuss the grim link between OSA and mental health.

American Sleep Apnea Association. https://www.sleepapnea.org/learn/sleep-apnea-information-clinicians/
Rising prevalence of sleep apnea in U.S. threatens public health. https://aasm.org/rising-prevalence-of-sleep-apnea-in-u-s-threatens-public-health/
Comorbidities associated with obstructive sleep apnea: a retrospective study. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4835326/
Obstructive sleep apnea and comorbidities: a dangerous liaison. https://mrmjournal.biomedcentral.com/articles/10.1186/s40248-019-0172-9
Obstructive sleep apnoea and obesity. https://www.racgp.org.au/afp/2017/july/obstructive-sleep-apnoea-and-obesity/
Interactions between obesity and obstructive sleep apnea. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021364/
Obstructive sleep apnoea and type 2 diabetes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983096/