"Morningness" and "Eveningness" represent lifestyle patterns including sleep-wake patterns. Although previous studies described a relationship between the morningness-eveningness trait and glycemic control in patients with type 2 diabetes mellitus (T2DM), the mechanism underlying this association remains unknown. The study participants comprised 725 Japanese T2DM outpatients free of history of cardiovascular diseases. Various lifestyles were analyzed using self-reported questionnaires, including morningness-eveningness questionnaire (MEQ). The relationships between morningness-eveningness trait and various biochemical parameters were investigated by linear regression analysis and logistic regression analysis. We classified the study patients into three groups, morning type (n=117), neither type (n=424) and evening type (n=184). Subjects of the evening type had high levels of alanine aminotransferase, triglyceride, fasting blood glucose and HbA1c and low high-density lipoprotein-cholesterol level in a model adjusted for age and gender. Furthermore, multivariate analysis showed that the evening type was associated with high HbA1c and estimated glomerular filtration rate even after adjustment for other lifestyle factors known to affect metabolic control. The results suggest that T2DM patients with eveningness trait are under inadequate metabolic control independent of other lifestyle factors. Thus, the evening trait of T2DM patients represents an important target for intervention to ensure appropriate metabolic function.
Keywords: Biochemical parameters; morningness–eveningness questionnaire; type 2 diabetes mellitus.