Premeal Whey Protein Lowers Postprandial Blood Glucose in Women With Gestational Diabetes Mellitus: A Randomized, Crossover Clinical Trial

OBJECTIVE: To examine how whey protein served as a premeal affects postprandial glucose excursions in women with gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: A placebo-controlled, single-blinded, crossover, randomized trial including women with and without GDM (20-36 weeks' gestation) was performed. Participants were studied in the laboratory and at home. In the laboratory, women were randomized to consume 20 g of whey or placebo 30 min before undergoing, 7-14 days later, a 75-g oral glucose tolerance test (OGTT). Blood was sampled consecutively 3 hours following the OGTT. The primary end point was the incremental area under the curve (iAUC) for glucose. At home, participants wore continuous glucose monitors and, on subsequent days, randomly consumed 0, 10, 15, 20, and 30 g of whey 30 min before breakfast. RESULTS: Twelve women with GDM and 12 pregnant women with normal glucose tolerance (NGT) to part in the trials. Intake of premeal whey resulted in lowered peak glucose by -1.0 mmol/L (95% CI -1.6 to -0.4) in women with GDM and -0.7 mmol/L (95% CI -1.3 to -0.1) in women without GDM compared with placebo. Insulin, glucose-dependent insulinotropic polypeptide, and glucagon-like peptide-1 levels increased rapidly after whey consumption in both groups. At home, a premeal of 30 g of whey dose-dependently reduced incremental glucose peaks with a maximum of -2.0 mmol/L (95% CI -2.5 to -1.5) in women with GDM compared with placebo. CONCLUSIONS: Premeal whey consumption acutely lowers postprandial blood glucose in women with GDM and those with NGT, with 15-30 g lowering the glucose iAUC of women with GDM. These findings emphasize the need for long-term studies to assess the impact of whey premeals in pregnancies affected by GDM.