Optimizing glycemic variability in type 2 diabetes using simple dietary and culinary recommendations to modulate starch digestibility: a randomized controlled trial

BACKGROUND: In type 2 diabetes (T2D), postprandial glycemic excursions significantly contribute to glycemic variability (GV) and cardiovascular disease risk. Because starch is the main carbohydrate source, controlling its digestibility in the daily diet to promote a gradual glucose release represents a promising nutritional strategy to reduce GV and improve glycemic control. OBJECTIVES: We investigated the feasibility and efficiency of a 3-mo dietary intervention emphasizing slowly digestible starch (SDS) through commercial starchy product supply and dietary and culinary counseling, on GV, glycemic control and cardiometabolic profile in patients with T2D with suboptimal control. METHODS: In a randomized, parallel, single-blind, controlled trial, 51 patients with T2D completed a 12-wk high-SDS (H-SDS) or low-SDS (L-SDS) diet. Participants received commercial starchy products either high or low in SDS content, with specific dietary/culinary counseling. Mean amplitude of glycemic excursions (MAGE) and other intra- and interday GV parameters were assessed by continuous glucose monitoring system (CGMS), as well as glycemic control and cardiometabolic parameters. RESULTS: Compared with the L-SDS diet, the H-SDS diet significantly lowered MAGE over 12 wk {β = 30.4 [95% confidence interval (CI): 12.4, 48.5]; P = 0.0025} and other intra- and interday GV parameters [SD, Coefficient of Variation, Continuous Overall Net Glycemic Action (CONGAs), Mean of Daily Differences (MODD)] with 96% compliance throughout the study. Glycated hemoglobin (HbA1c) decreased in both groups, with a trend toward a greater reduction in the H-SDS group [β = 0.3 (95% CI: 0.05, 0.47); P = 0.0981], where HbA1c fell below the 7% target. Other cardiometabolic markers were similar between diets. CONCLUSIONS: Modulating starch digestibility represents an effective and accessible strategy for enhancing GV and thus glycemic management in T2D, allowing patients with suboptimal glycemic control to reach recommended glycemic targets. This trial was registered at clinicaltrials.gov as NCT03847701.