Sleep disorders and type 2 diabetes mellitus: a narrative review of evolving research disciplines, conceptual pathways, and clinical implications

Abstract

Sleep disturbances—including insomnia, obstructive sleep apnea, and circadian rhythm disruption—are increasingly recognized as important yet understudied contributors to Type 2 Diabetes Mellitus (T2DM). Prior reviews typically focus on single disorders or mechanisms, limiting understanding of how different scientific traditions conceptualize the sleep–T2DM relationship. This narrative review followed RAMESES publication standards to synthesize how four research disciplines—endocrinology, sleep medicine, behavioral science, and chronobiology—have investigated sleep disturbances in T2DM. Searches were conducted in PubMed, Scopus, Web of Science, ProQuest, and EBSCO (final search: 17 January 2025). Of 2,074 records identified, 62 English-language documents met inclusion criteria. Studies were appraised using tradition-specific criteria, and findings were integrated through chronological storyline development and cross-tradition synthesis. Across traditions, insufficient, fragmented, or mistimed sleep was consistently linked to insulin resistance, impaired glucose tolerance, appetite dysregulation, and adverse body composition. Endocrinology emphasized hormonal, inflammatory, and oxidative pathways; sleep medicine focused on obstructive sleep apnea (OSA) and insomnia, with mixed evidence for continuous positive airway pressure (CPAP) effects on HbA1c. Behavioral research highlighted the influence of disturbed sleep on appetite, self-regulation, and treatment adherence. Chronobiology demonstrated the metabolic consequences of circadian misalignment and variability in melatonin signaling. Although key mechanistic themes converged, the majority of studies were observational or short-term experimental, limiting causal inference; instead, each tradition emphasized distinct explanatory frameworks and variables of interest in linking sleep with metabolic outcomes. Sleep disturbances appear to be modifiable components of a broader metabolic and psychosocial network in T2DM. Incorporating structured sleep assessment and targeted interventions—such as cognitive behavioral therapy for insomnia (CBT-I), CPAP for obstructive sleep apnea, and circadian-based strategies including scheduled light exposure and sleep–wake regularization—may enhance clinical outcomes. A tradition-sensitive synthesis clarifies sources of divergence in the literature and provides a foundation for more coherent, mechanism-informed research.