Comparison of carbohydrate assessment metrics for predicting fasting and postprandial plasma glucose in patients with type 2 diabetes mellitus.

BACKGROUND

Fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) are critical short-term indicators of glycemic control in type 2 diabetes mellitus (T2DM). Although carbohydrate assessment metrics - carbohydrate (g/d), carbohydrate portion, carbohydrate (%), low carbohydrate diet (LCD) score, carbohydrate to fiber ratio (CFR), and dietary fiber (DF) - may differ in predicting FPG and PPG, their comparative efficacy is unclear. This study aims to identify the most predictive carbohydrate assessment metrics for FPG and PPG, facilitating timely dietary interventions to optimize glycemic management in patients with T2DM.

METHODS

This cross-sectional study assessed six carbohydrate metrics in 238 patients with T2DM. FPG and PPG were measured (uncontrolled: FPG ≥7.0mmol/L, PPG ≥10.0mmol/L). Multiple logistic regression and the receiver operating characteristic curve (ROC) analyses evaluated predictive performance.

RESULTS

Carbohydrate (%) and LCD score were the strongest predictors of FPG and PPG. Higher carbohydrate (%) was significantly associated with poorer FPG (OR, 0.942, 95%CI, 0.907-0.979, P<0.01) and PPG control (OR, 0.920, 95%CI, 0.875-0.968, P<0.01), while higher LCD score improved odds of control (FPG: OR, 1.073; PPG: OR, 1.128, both P<0.01). ROC analysis identified carbohydrate (%) as the optimal predictor for PPG (AUC, 0.7201, cutoff >51.50%; sensitivity, 80.77%) and FPG (AUC, 0.6751, cutoff >55.50%; sensitivity, 66.47%), followed by LCD score (PPG AUC, 0.7153; FPG AUC, 0.6689).

CONCLUSION

Carbohydrate (%) and LCD score most effectively predict short-term glycemic control in T2DM. Limiting carbohydrate intake to ≤51.5% (PPG) or ≤55.5% (FPG) of energy and achieving LCD scores >23.5 (PPG) or >16.5 may optimize outcomes, guiding personalized dietary interventions.