Since protein ingestion is known to stimulate the secretion of glucagon-like peptide-1 ( GLP-1 ), researchers have hypothesised that enhancing GLP-1 secretion to harness its insulinotropic / beta cell-stimulating activity with whey protein pre-load may have beneficial glucose-lowering effects in type 2 diabetes mellitus.
In a randomised, open-label crossover clinical trial, researchers studied 15 individuals with well-controlled type 2 diabetes mellitus who were not taking any medications except for sulfonylurea or Metformin.
These participants consumed, on two separate days, 50 g whey in 250 ml water or placebo ( 250 ml water ) followed by a standardised high-glycaemic-index breakfast in a hospital setting.
Participants were randomised using a coin flip.
The primary endpoints of the study were plasma concentrations of glucose, intact GLP-1 and insulin during the 30 min following meal ingestion.
In each group, 15 patients were analysed. The results showed that over the whole 180 min post-meal period, glucose levels were reduced by 28% after whey pre-load with a uniform reduction during both early and late phases.
Insulin and C-peptide responses were both significantly higher ( by 105% and 43%, respectively ) with whey pre-load. Notably, the early insulin response was 96% higher after whey.
Similarly, both total GLP-1 ( tGLP-1 ) and intact GLP-1 ( iGLP-1 ) levels were significantly higher ( by 141% and 298%, respectively ) with whey pre-load.
Dipeptidyl peptidase 4 plasma activity did not display any significant difference after breakfast between the groups.
In conclusion, consumption of whey protein shortly before a high-glycaemic-index breakfast increased the early prandial and late insulin secretion, augmented tGLP-1 and iGLP-1 responses and reduced postprandial glycaemia in type 2 diabetic patients.
Whey protein may therefore represent a novel approach for enhancing glucose-lowering strategies in type 2 diabetes mellitus. ( Xagena )
Jakubowicz D et al, Diabetologia 2014; 57: 1807-1811