A Systematic Review of the Association between Sleep Quality and Glycemic and Other Metabolic Indicators in Individuals with Type 2 Diabetes

Abstract

Background: There is an association between sleep quality and glycemic control outcomes, particularly glycated hemoglobin (HbA1c), fasting plasma glucose, and related metabolic markers in adults with type 2 diabetes mellitus. Purpose: This review aims to examine the mentioned association and includes studies conducted in accordance with current methodological and diagnostic standards. Methods: Research published between 2010 and 2025 and indexed in international databases was screened according to predefined inclusion criteria, which required studies to involve adults with type 2 diabetes and to assess the relationship between sleep quality and glycemic outcomes. Sleep quality was evaluated through parameters, such as sleep duration, continuity, sleep onset latency, and subjective sleep satisfaction. Eligible studies were compared based on glycemic control indicators, particularly HbA1c (Hemoglobin A1c), which is recognized as a primary metabolic outcome influenced by sleep quality. Results: A total of 24 studies meeting the criteria were included after screening seven databases. The findings indicate that insufficient and poorquality sleep is generally associated with elevated HbA1c levels, impaired glucose tolerance, increased insulin resistance, and adverse lipid profiles. Furthermore, some studies have reported that sleep disorders may negatively affect the course of diabetes by contributing to increased inflammatory markers. Conclusion: The findings suggest that sleep quality is an important lifestyle factor to consider in the management of type 2 diabetes. Implications for Nursing: The results underscore the importance of healthcare professionals integrating sleep assessments and interventions into clinical practice for individuals with diabetes. Keywords: Adults, Metabolic variables, Sleep quality, Systematic review, Type 2 diabetes.