Study finds relationship between diabetes and OSA cofactors in development of CVD.
It has been observed in many studies that diabetes and obstructive sleep apnea (OSA) are risk factors for cardiovascular disease. This has led researchers to theorize that there may be a connection between diabetes and OSA, with many bidirectional pathologies being suggested, but no actual bidirectional study has been conducted.
Previous studies have shown OSA leading to diabetes. This study simultaneously observed three prospective cohorts of healthcare workers over 10–18 years to determine whether diabetes predicted OSA and vice versa. The three cohorts were pulled from The Nurses’ Health Study (68,590 females), Nurses’ Health Study II (75,082 females), and Health Professionals Follow-up Study (22,916 males).
From three studies, 166,588 doctors and nurses were sent baseline questionnaires identifying both diabetes and OSA and were updated for new diagnoses every two years.
For those previously diagnosed with diabetes, another survey was sent on symptoms, diagnostic test, and treatment. There was a confirmation of type 2 diabetes if the criteria set forth by the National Diabetes Data Group was met. Medical records confirmed diagnoses in a validation study. Thereafter patients who have diabetes were categorized on whether they took oral meds, insulin, or no meds. Participants were also surveyed on obstructive sleep apnea diagnoses. There were 13.8% of men and 6.4% of women who reported having sleep apnea, which aligns with national averages. Those who reported feeling overly drowsy more than four days a week were considered to have excessive daytime sleepiness. Patients were then categorized by severity of OSA based on survey questions. Many covariates, including lifestyles, amount of physical activity, and working the night shift, were also assessed. Cox proportional hazards models estimated hazard ratios and confidence intervals were used to compare OSA vs non-OSA status among patients who have diabetes. A separate model adjusted for time-related BMI and waist circumference since these were predictors of both diabetes and OSA.
A proposed mechanism for the development of diabetes in patients with OSA is that recurrent hypoxemia, hyperactivity of the autonomic nervous system, and sleep disturbances can lead to inflammation, insulin resistance, glucose intolerance, and beta cell dysfunction seen in diabetes. During midpoint follow-up 1,974 women and 1,139 men reported being diagnosed with obstructive sleep apnea. These patients had higher BMI’s and were overall unhealthier then their counterparts who did not have OSA. Upon follow-up over the course of 10 to 18 years, 7,592 women and 1,437 men developed diabetes.
The age and BMI-adjusted confidence interval for patients with OSA vs those without OSA was significant 1.37 [1.24-1.52]. The study also found that the more severe the OSA, the higher the risk for developing diabetes, with the highest risk in those with EDS 1.78 [1.13,2.82].
Diabetes may cause breathing problems by altering ANS (autonomic nervous system) activity, and impairing ventilatory control. Midpoint follow-up also revealed 6,838 women and 1,118 men having diabetes with a total of 7,259 women and 2,105 men diagnosed with incident OSA. Analysis of this group uncovered a 43% higher OSA risk in women taking insulin 1.60 [1.34-1.89] when compared to people who do not have diabetes. No other categories were statistically significant, i.e. oral antiglycemic medications, no medications, or male gender.
This study supports a bidirectional relationship between diabetes and OSA. Obstructive sleep apnea independently showed a 37% higher risk of diabetes, with the risk increasing with severity of OSA. The reverse relationship is also true, especially for women taking insulin for their diabetes who have a 43% higher OSA risk. There are a number of physiological mechanisms theorized for this bidirectional relationship, but further research is needed.
Due to the large size of this study, self-reporting was the best method. However, due to both these diseases being underdiagnosed, the actual numbers may be higher, but there was a long follow-up time to correct for this. This study gave a general picture, as researchers did not have access to the patient’s personal therapy and how it is affecting their glycemic numbers, or the development of additional complications. Although BMI and waist circumference were accounted for, a predictor of OSA that was not measured was body fat deposition, namely neck fat. This study coincided with previous observations and was a good account due to the details provided by healthcare professionals on their own disease states.
- Obstructive sleep apnea independently showed a 37% higher risk of diabetes, with the risk increasing with severity of OSA.
- The reverse relationship is also true, especially for women taking insulin for their diabetes who have a 43% higher OSA risk.
- Patients who have one disease state should be encouraged to be vigilant about the signs/symptoms of the other disease state.
Huang, Tianyi, et al. “A Population-Based Study of the Bidirectional Association Between Obstructive Sleep Apnea and Type 2 Diabetes in Three Prospective U.S. Cohorts.” Diabetes Care, vol. 41, no. 10, 2018, pp. 2111–2119., doi:10.2337/dc18-0675.
Arsalan Hashmi, PharmD. Candidate, LECOM College of Pharmacy