Abstract
Sleep disturbances are increasingly recognized as factors that might influence metabolic health and diabetes outcomes. However, the relationship between different sleep-related disorders and glycemic control in individuals with type 2 diabetes mellitus (T2DM) remains incompletely understood. This systematic review aimed to evaluate the association between sleep disturbances and glycemic outcomes in adults with T2DM. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Databases were searched for studies published between January 2000 and January 2026. Eligible studies included adults with T2DM who were assessed for sleep-related factors, including sleep quality, sleep duration, insomnia, circadian rhythm disturbances, and obstructive sleep apnea, and who reported glycemic outcomes such as glycated hemoglobin (HbA1c) or blood glucose measures. A total of 8,100 records were identified, of which 25 studies met the eligibility criteria and were included in the final qualitative syn thesis. Overall, the evidence demonstrated a consistent association between sleep disturbances and poorer glycemic control. Poor sleep quality was frequently associated with higher HbA1c levels and less favorable glucose regulation. Both short and prolonged sleep duration were linked to adverse glycemic outcomes, although the association was generally more consistent for short sleep duration. Taken together, the available evidence suggested that sleep disturbances represent an important and potentially modifiable factor influencing glycemic control in adults with T2DM. Incorporating sleep assessment into routine diabetes care might contribute to more comprehensive disease management, although further longitudinal and interventional studies are needed to clarify causality and determine the effectiveness of sleep-focused interventions.

Key words: Type 2 diabetes mellitus, sleep disturbances, sleep quality, insomnia, obstructive sleep apnea, glycemic control, HbA1c, systematic review