Table 1.

The PECO framework for the Eligibility criteria.

PECO framework	Description of the inclusion criteria	Exclusion criteria
Population	Adult individuals aged 18 years and above of both sexes and different races or ethnicities, using original studies published in the English language between January 1, 2011, and March 30, 2023	Pregnant participants, due to the physiological effect of pregnancy on sleep, participants under 18 years. Studies have not been published in the English language.
Exposure	Patients with OSA and T2DM who participated in observational studies. The most recent publication will be included when multiple publications using the same dataset and similar aims are found	Interventional studies since the focus is to understand the methods used to understand the link between OSA and T2DM. Randomised clinical trials, Systematic reviews, conference abstracts, and case reports
Comparison	Compare the different methods, assessment procedures, and statistical analysis. Eligible studies must include a comparative group that has no disease (control group free of OSA or T2DM)	Studies that only included descriptive analysis and prevalence were excluded. Studies without a control group
Outcome	The methods used to understand the association between OSA and T2DM	This review will not address the prevalence of OSA and T2DM or the strength of their association

OSA, obstructive sleep apnea; T2DM, type 2 diabetes mellitus.