SAN FRANCISCO — People with obstructive sleep apnea have almost three times the risk of developing type 2 diabetes, according to a poster presentation by Dr. Nader Botros at the International Conference of the American Thoracic Society.
This increase in risk is independent of obesity, hypertension, age, race, and gender, commented Dr. Botros of Yale University, New Haven, Conn., in a press briefing.
Independent of other factors, obstructive sleep apnea (OSA) increases the risk of developing diabetes by 2.7 times. This is about the same magnitude as the increase in risk conferred by obesity alone, which was 2.9-fold increase in the study, Dr. Botros reported.
The study involved 544 patients who had been referred to the sleep laboratories at the Veterans Affairs Connecticut Healthcare System in West Haven, for an evaluation of suspected sleep-disordered breathing.
None of the patients included in the study had a known history of type 2 diabetes. Each patient underwent a full attended polysomnogram and was followed for up to 5 years.
Dr. Botros and his coinvestigators compared the 402 patients who were diagnosed with OSA with the 142 patients who did not qualify for the diagnosis.
Confirming other studies, patients with OSA were significantly older and heavier than the control patients were. Significantly greater percentages of patients with OSA were men and had hypertension at baseline.
The investigators divided the patients into quartiles based on their apnea-hypopnea index (AHI), a measurement of the severity of sleep apnea.
Compared with patients in the lowest quartile (those who had an AHI of less than 7), patients in the highest quartile (those with an AHI at least 46) had 4.6 times the risk of developing diabetes. Patients who were in the second and third quartile had intermediate hazard ratios, and the trend was statistically significant.
When the degree of hypoxia as measured by oxygen saturation was added to the multivariate analysis, OSA alone no longer emerged as a significant predictor of the development of type 2 diabetes, whereas hypoxia conferred a 2.9-fold increase in risk.
This indicates that at least some of the risk that was conferred by OSA can be explained by hypoxia.
The exact link between OSA, hypoxia, and type 2 diabetes remains unknown, Dr. Botros said, but there is evidence that sleep apnea activates the body's fight-or-flight response.
This in turn triggers a cascade of events including the production of high levels of cortisol, which has been tied to the development of insulin resistance and glucose intolerance. If these prediabetic conditions are left untreated, it can lead to the development of full-blown diabetes.
“Our next step will be to determine whether the treatment of sleep apnea can improve an individual's diabetic parameters and consequently the negative health affects of diabetes,” Dr. Botros said in a prepared statement.
This increase in risk for diabetes is independent of obesity, age, hypertension, race, and gender. DR. BOTROS