Late eating is associated with poor glucose tolerance, independent of body weight, fat mass, energy intake and diet composition in prediabetes or early onset type 2 diabetes.

This study investigates the impact of habitual late calorie intake on glucose metabolism in adults with overweight or obesity and diet or metformin-controlled prediabetes or type 2 diabetes independently of body weight, fat mass, energy intake or diet composition. Participants (n = 26) were classified as Later Eaters (LE) if ≥45% daily calories were consumed after 5 pm and Early Eaters (EE) if not, based on daily caloric intake assessed over 2-wk. EE and LE did not differ in anthropometrics or daily energy intake, but LE consumed more carbohydrates (p = 0.038) and fats (p = 0.039) after 5 pm. Fasting glucose, insulin, and C-peptide did not differ between groups but LE exhibited higher glucose concentrations after an oral glucose tolerance test (p = 0.001), even after adjusting for body weight, fat mass, energy intake and diet composition (p < 0.05). Glucose results remained when participants with T2D were excluded (p = 0.031). After diabetes status adjustment, differences in glucose concentrations were higher in LE for time 30 (p = 0.028) and 60 min (p = 0.036). LE, compared to EE, had poorer glucose tolerance, independent of body weight, fat mass, daily energy intake and diet composition. ClinicalTrials.gov: NCT04465721.