Association of Carbohydrate Quantity and Quality with the Progression of Prediabetes to Type 2 Diabetes and Regression to Normoglycemia: A 9-year Follow-up in Tehran Lipid and Glucose Study

This study aimed to determine the association between the quality and quantity of dietary carbohydrate (CHO) with the risk of pre-diabetes (pre-DM) progression to type 2 diabetes (T2D) and the chance of returning to normal glycemia.

 Dietary CHO quantity (total CHO and dietary fiber) and quality (glycemic index, glycemic load, insulin index, and insulin load) were assessed using a 168-item, semi-quantitative, valid, and reliable food frequency questionnaire in 334 men and women with pre-DM at baseline. The participants were followed for a median of 9 years. Fasting and 2-hours (after oral loading of 75 g glucose) plasma glucose concentrations were measured at baseline and subsequent examinations.

 During the study follow-up, 39.8% of the pre-DM subjects progressed to T2D, and 39.8% returned to normal glycemia. Dietary total CHO, glycemic index, glycemic load, insulin index, and insulin load were not significantly associated with pre-DM regression and progression during the study follow-up. A 25% reduced risk of developing T2D was observed per 5 g/1000 kcal per day by the increased dietary intake of fiber (odds ratio: 0.75, 95% CI: 0.58-0.98; P=0.038).

Total CHO intake and its quality were not associated with the change of glycemic status in pre-DM subjects, while higher intakes of dietary fiber decreased the risk of pre-DM progression to T2D.