P4386Chronotype and diabetes in middle-aged and elderly people: Importance of mismatch between chronotype and actual lifestyle

Abstract

Background: Chronotype is a behavioral manifestation of circadian clock, and was classified to morning-type (M-type), evening-type, and neither type. On the other hand, sleep-wake cycle, primarily determined by bedtime and wake-up time, is voluntary and is a manifestation of life style. Mismatch between the chronotype and sleep-wake cycle may lead to cardio-metabolic disorder including obesity. Purpose: We compared the prevalence of diabetes in four groups divided by the chronotype (M type or non-M type) and bedtime (late bedtime or not) in middleaged and elderly population. Methods: This is a cross-sectional study involving 821 participants without CVD, aged 40 to 82 (median 55) years, who underwent general health examinations. Of these, 70 (9%) had diabetes (defined as taking antidiabetic medication and/or HbA1c ≥6.5). We assessed self-reported bedtime, and chronotype using the Horne and Ostberg's Morning-Eveningness Questionnaire, which consist of 19 items on sleep habits and fatigue (each item gives scores 0, 1, 2, 3, 4, 5, or 6) and the sum of score ranged from 16 to 86; M-type and non-M type (neither type plus evening type) were defined as a score ≥59, and <59, respectively. Late bedtime was defined as after 23:00. Results: M-type was significantly associated with diabetes (OR, 1.86; 95% CI, 1.04-3.42; p<0.05), after adjusting for age, gender, body mass index, smoking, drinking, sleep duration, and presence of hypertension, and dyslipidemia. Late bedtime alone was not associated with diabetes. However, the multivariable odds ratio for diabetes was significantly higher in a group with a combination of M-type and late bedtime (Table). Conclusion: M-type was associated with diabetes in middle-aged and elderly people. Particularly, the odds ratio for diabetes was 3.2 in group of M-type and late bed time, suggesting that mismatch between internal circadian rhythms and behavioral pattern (i.e. circadian misalignment) could play a significant role for development of diabetes. (Table Presented).