A 7-day study of continuous glucose monitoring and chrononutrition in healthy normoglycemic individuals shows higher glucose variability in late chronotypes than in early chronotypes

The late chronotype trait appears as a risk factor for developing diabetes, but data from healthy individuals are scarce. This study aimed to compare healthy individuals (19-35 y, BMI < 30 kg/m², no prediabetes, medication-free) presenting with the late or early chronotype (23 LT, 21 ET) for differences in tissue glucose concentration and its relationship with chrononutrition habits. Glucose metrics (mean, variability, times in normative/hyperglycemic/hypoglycemic ranges) and chrononutrition parameters (eating times/frequency/regularity/window) were recorded over 7 d under daily life conditions, using blinded continuous glucose monitoring and daily log. LT showed a higher 24-h glucose variability than ET due to a greater day-to-night fluctuation in mean glucose. LT had later eating times than ET, although their first eating occasion occurred at a similar time interval after wakeup. LT had a more irregular eating frequency across the week than ET. Chrononutrition parameters were associated differently with glucose variability in LT and ET. The findings support even for healthy young adults the notion that the LT is associated with a poorer glucose state. Glucose variability appears to be more sensitive than glucose mean for detecting early dysregulation of glucose metabolism. Chrononutrition may affect glucose variability differently in LT and ET, which deserves further examination.