Notably, the risk of type 2 diabetes increases with increasing OSA severity.
The study, “Obstructive sleep apnoea, prediabetes, and progression of type 2 diabetes: A systematic review and meta-analysis,” was published in the Journal of Diabetes Investigation.
Obstructive sleep apnoea (OSA) occurs when the upper airways partially or fully close during sleep, stopping airflow and breathing for short periods. It affects sleep quality and is linked to an increased risk of type 2 diabetes. However, there is conflicting evidence on the association of OSA with prediabetes – defined as impaired fasting glucose, impaired glucose tolerance or a combination of both.
Now, a team of researchers combined the results of multiple cohorts and cross-sectional studies (reporting a relationship between OSA and prediabetes or type 2 diabetes and compared the rates of prediabetes among people with and without OSA. They also investigated if the rates of prediabetes varied according to OSA severity.
The researchers only evaluated studies published between 2011 and 2021 where participants were clinically diagnosed with OSA using gold standards and the apnoea-hypopnea index (AHI) – defined as the number of apnoeas (cessation of breathing) and hypopneas (excessively shallow or abnormally low respiratory rate) per hour of sleep – was measured. Participants were grouped into four categories based on AHI index: none, mild, moderate, or severe AHI.
A total of 25 studies including 154,948 participants were included in the final analysis. Compared to participants without OSA, the rates of impaired fasting glucose and impaired glucose tolerance were 2.34-fold and 58% higher, respectively, in participants with OSA. The incidence of type 2 diabetes was also 2-fold higher in participants with OSA in cohort studies and 3.6-fold higher in cross-sectional studies.
The risk of type 2 diabetes increased according to OSA severity in the cohort and cross-sectional studies. In cohort studies, participants with mild, moderate, and severe OSA had a 25%, 76%, and 2.73-fold higher risk of type 2 diabetes than participants without OSA. The cross-sectional studies also showed similar results with participants with mild, moderate, and severe OSA showing a 2.88, 3.08 and 4.12-fold higher risk of type 2 diabetes than the control group.
“The main results of our analysis show that OSA is associated with an increased prevalence of prediabetes/diabetes. Among the patients with OSA, the prevalence of diabetes seemed to increase with increased AHI,” the researchers wrote.
Since OSA has a strong association with prediabetes and type 2 diabetes, it is essential that health care professionals screen patients presenting with either condition for the other so that treatment or lifestyle interventions can be initiated early to prevent complications.
“Our findings support an association of OSA with the presence of prediabetes/diabetes and suggest that healthcare providers working in the fields of diabetes and OSA should screen patients presenting with one condition for the presence of the other. Early intervention can prevent both diabetic and cardiovascular events,” they wrote.
The researchers highlighted several limitations of the study, including the cross-sectional design of the studies included and the inability to assess whether OSA increases the risk of developing prediabetes.
“In conclusion, our study provides further evidence that OSA is closely correlated with prediabetes and diabetes risk; the prevalence of prediabetes/diabetes in patients with OSA was higher than that of patients without OSA.”
Further studies are required to determine whether diagnosing OSA early in people with prediabetes and type 2 diabetes and early treatment could improve survival in this population.