Association of diet composition and meal intervals with short-term glycemic control and glycemic variability among type 2 diabetes mellitus patients

BACKGROUND: Glycemic variability (GV) is an independent contributor to diabetes related complications beyond glycated hemoglobin. While dietary macronutrient composition influences glycemic responses, the importance of meal timing and nutrient distribution in real world settings remain unclear particularly in Indian diets. METHODS: In this observational study, 47 adults with type 2 diabetes mellitus who completed 10-14 days of continuous glucose monitoring (CGM) were included in the final analysis. The median CGM wear duration was 14(14-14) days and the median CGM analyzed days was 11(10-11) days. Associations between dietary variable and CGM derived metrics including Time in Range (TIR), Time above Range (TAR) and percentage coefficient of variation (%CV) were assessed using Spearman correlation and multivariable mixed-effects regression models adjusted for total energy intake, body mass index (BMI), HbA1c, and insulin/insulin-secretagogue use. RESULTS: Higher carbohydrate intake was associated with higher %CV (ρ = 0.354, p = 0.017), higher TAR (ρ = 0.343, p = 0.021), higher average glucose (ρ = 0.355, p = 0.017), and lower TIR (ρ = -0.378, p = 0.010) in subject-level analyses. Longer lunch-dinner and breakfast-dinner intervals were associated with higher TIR, whereas the breakfast-lunch interval showed no clear association with glycemic outcomes. In mixed-effects analyses accounting for repeated observations and participant-level covariates, habitual dietary carbohydrate composition remained associated with glycemic variability, whereas meal-timing associations were less consistent after adjustment. CONCLUSIONS: Habitual dietary carbohydrate composition remained associated with glycemic variability, whereas meal-timing associations were less consistent in adjusted analyses. Future studies are needed to clarify the role of dietary timing strategies in optimizing CGM-derived glycemic outcomes. CLINICAL TRIAL NUMBER: Not applicable.