Effects of low-GI biscuits as pre-loads or mid-meal snacks on post-prandial glycemic excursions in women with recent gestational diabetes: A protocol for a randomized crossover trial and an extended tailored intervention

Abstract

Background: Increased post-prandial glycemic excursions contribute to the development of diabetes and have been observed in women with recent gestational diabetes mellitus (GDM) and with normal glucose tolerance at post-partum. As a convenient meal replacement, low-GI biscuits are helpful for improving glycemic excursions in patients with type 2 diabetes. However, it is unknown whether low-GI biscuits as pre-loads or mid-meal snacks have a better effect in diminishing post-prandial glycemic excursions from the individual level in women with recent GDM. Therefore, the aim of this trial is to tailor a better dietary strategy utilizing low-GI biscuits (Fitmeal) to improve post-prandial glycemic excursions through within-subject comparison in such a population and observe the long-term effect of a tailored dietary approach in glycemic control.

Methods: We have designed a two-phase trial including a randomized, crossover, non-blinded trial in the first phase, followed by a 4-week tailored intervention in the second phase. A total of 52 post-partum women with recent GDM will be allocated into four meal plans: (1) Fitmeal pre-load 30 min before standard lunch meal (P+L), (2) Fitmeal as a mid-meal snack 2 h before standard lunch meal (S+L), (3) isocaloric standard control with co-ingestion of Fitmeal and standard lunch meal (CL) at the same time, and (4) placebo control with 200 ml of water taken 30 min before standard lunch meal (W + L), on four consecutive days. Acute post-prandial glycemic response (PGR) measured by continuous glucose monitoring (CGM) will be compared among the four meals. In the second phase, all participants will receive a 4-week tailored intervention using Fitmeal as pre-loads or mid-meal snacks based on within-subject PGR results from the first phase. Glycemic metrics, dietary behaviors, and psychosocial factors (e.g., quality of life, self-efficacy, perceived stress, and depression) will be examined at baseline and end-point.

Discussion: This trial is expected to optimize the use of low-GI biscuits as pre-loads or mid-meal snacks in improving individual post-prandial glycemic excursions among women with recent GDM. Furthermore, the findings of this study will provide novel information on how to deliver an effective dietary intervention at the individual level and guide future clinical practice of medical nutrition therapy for diabetes prevention.

Trial registration number: Chinese clinical trial registry, ChiCTR2200060923.

Keywords: continuous glucose monitoring; gestational diabetes; glycaemic index; post-prandial glycaemic response; pre-load.

Figure 1

Randomized crossover design. Participants will complete four test meals over 4 consecutive days in a randomized counterbalanced order using Latin Square Design. Participants will be randomized to receive one of the four meal arrangement orders as follows: (1) P + L → S + L → W + L → CL; (2) S + L → CL → P + L → W + L; (3) CL → W + L → S + L → P + L; (4) W + L → P + L → CL → S + L. To diminish the glycemic impact from the last meal, breakfast, lunch, pre-load, and mid-meal snack foods are provided, with breakfast and lunch identical for 4 test days. 3h-iAUC after each lunch using continuous glucose monitoring (CGM) will be calculated as the primary outcome (P, Pre-load; S, Mid-meal snack; B, Breakfast; L, Lunch; W, Water; C, Co-ingestion; iAUC, Incremental areas under the curve of post-prandial glycemic response; P + L, Fitmeal pre-load 30 min before lunch; S + L, Fitmeal as mid-meal snack 2 h before lunch; CL, Co-ingestion of Fitmeal with lunch; W + L, Drinking water 30 min before lunch).

Figure 2

Study design flow chart.