Association between chronotype and cardio-vascular disease risk factors: A systematic review and meta-analysis

Abstract

Introduction: Circadian rhythm influences individuals' chronotype or morning-evening preferences. Chronotype affects an individual's lifestyle behaviors, social and work pattern, and even development of cardiovascular risk factors and diseases. This review aimed to examine the association between the chronotype and cardio-vascular risk factors. Methods: We systematically reviewed the association between chronotype and type 2 diabetes mellitus (T2DM). We searched relevant observational studies in PubMed, Embase, Scopus databases and adhered to the PRISMA guidelines and meta-analysis was performed to get the pooled odds ratios and mean differences using the random effects model. Results: Thirteen eligible studies were systematically reviewed, of which six studies were included in meta-analysis. Evening chronotype was significantly associated with higher odds of T2DM (OR 1.17; 95% CI: 1.13 to 1.22) and a higher Hemoglobin A1c level (Mean difference: 0.35; 95% CI: 0.06 to 0.65) as compared to the morning chronotype participants. Sensitivity analysis showed 53% higher odds of T2DM in evening chronotype participants when Morningness -Eveningness Questionnaire was applied in the studies, however, the result was statistically not significant. Conclusion: Evening chronotype was significantly associated with T2DM and higher HbA1c level than with morning-type. We need future large scale experimental or prospective longitudinal studies to explore the causal association between chronotype and T2DM.

Keywords

• Chronotype
• Diabetes
• Evening-type
• Morning-type
• Body mass index
• Morningness