The Impact of a Low Glycemic Load Breakfast on Diurnal Glucose Profiles in Women with Gestational Diabetes Mellitus: The GLIDING Randomized Crossover Trial

Background Medical nutrition therapy is first-line treatment in gestational diabetes (GDM) management, yet evidence-based approaches remain lacking. In women with GDM, increased morning insulin resistance often results in postprandial (breakfast) hyperglycemia, potentially leading to increased 24-h glycemic variability (GV).Objective In a short-term randomized crossover control trial, we compared the effects of a low glycemic load (GL) breakfast (LGL-B) to a high GL breakfast (HGL-B) on 1-h postprandial breakfast glucose (PPG) and 24-h GV (coefficient of variation [%CV]) in women with GDM.Methods Women were provided an LGL-B (245 kcal; 10.9g carbohydrate) and HGL-B (247 kcal; 43.4g carbohydrate) in random order for 7 days, separated by a 7-day washout. Fasting blood was drawn on Days 1, 8, 15 and 22 (pre/post 7-day interventions) and blinded continuous glucose monitoring was undertaken. Breakfast 1-h PPG and %CV were analyzed using mixed effect models to compare between intervention effects with Bonferroni adjustments.Results Of 32 women with GDM randomized (median 34.2 years, BMI 28.1 kg/m2, 27 weeks' gestation), 20 women completed both 7-day interventions and had ≥48-h CGM data for each breakfast intervention. Compared to an HGL-B, an LGL-B had lower 1-h PPG (HGL-B: mean 7.5 mmol/L [95% CI 7.2, 7.8]; 134 mg/dL [129, 140]; LGL-B: 5.0 mmol/L [4.7, 5.2]; 89 mg/dL [84, 94], pConclusions In women with GDM, an LGL-B was associated with lower breakfast PPG and 24-h %CV. Targeting breakfast may be a simple dietary strategy to improve glycemia and reduce morning bolus insulin requirements.Trial registration Australian and New Zealand Clinical Trials Registry (Identifier: ACTRN12623000425695) URL: https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12623000425695.