A ready-to-mix nutraceutical supplement (GLUBLOC) lowers postprandial blood glucose levels in healthy individuals — A randomised, placebo-controlled, crossover study

Background Fast-absorbing carbohydrates and sugars are broken down rapidly by the gut enzymes and can lead to rapid blood sugar and insulin spikes. Low-glycaemic index (GI) diets can be an important component of dietary management plans designed to help people with prediabetes and Type 2 Diabetes to lose weight and improve their overall glycaemic control. Methods In this randomised, placebo-controlled, crossover study, a novel ready-to-mix supplement made of powdered white mulberry leaf extract and apple peel extract (MLE + AE; Glubloc™) was tested to determine its effect on post-meal blood sugar spikes in healthy individuals when mixed and consumed with food containing fast-absorbing carbohydrates. Changes in postprandial blood glucose levels (baseline, 0, 30, 90 and 120 min) and iAUC were compared to placebo. Using in vitro models and enzymatic assays, the molecular mechanisms behind the glucose-lowering effect of MLE + AE were explored. Results MLE + AE powder blend, when mixed in the food, significantly reduced post-meal blood glucose iAUC measured at 0.5 h (− 45.2%, 4.9 (3.6, 6.1)), 1.0 h (− 41.3%, 8.6 (6.2, 10.9)), 1.5 h (− 41.2%, 11.6 (8.4, 14.9)), and 2.0 h (− 40.5%, 13.4 (9.2, 17.6)) when compared to placebo. A statistically significant change in Cmax and Tmax was observed, suggesting the positive impact of MLE + AE on the processing of fast-absorbing carbohydrates. MLE + AE powder inhibited α-amylase and α-glucosidase in dose-dependent manner, inhibited the enzyme (PTP 1B) responsible for insulin resistance and enhanced glucose uptake by modulating insulin-dependent and independent pathways. Conclusion MLE + AE powder when mixed with the high carbohydrate and sucrose meal, significantly reduced the postprandial blood glucose spike by reducing the rate of carbohydrate processing and by delaying its absorption. The mechanism is mainly attributed to its potential in inhibiting the enzymes responsible for carbohydrate digestion and by promoting the insulin-signalling pathways. The product is well tolerated and none of the subjects experienced major gastrointestinal side effects. Graphical Abstract