Effect of whey on blood glucose and insulin responses to composite breakfast and lunch meals in type 2 diabetic subjects

Am J Clin Nutr. 2005 Jul;82(1):69-75. doi: 10.1093/ajcn.82.1.69.


Background: Whey proteins have insulinotropic effects and reduce the postprandial glycemia in healthy subjects. The mechanism is not known, but insulinogenic amino acids and the incretin hormones seem to be involved.

Objective: The aim was to evaluate whether supplementation of meals with a high glycemic index (GI) with whey proteins may increase insulin secretion and improve blood glucose control in type 2 diabetic subjects.

Design: Fourteen diet-treated subjects with type 2 diabetes were served a high-GI breakfast (white bread) and subsequent high-GI lunch (mashed potatoes with meatballs). The breakfast and lunch meals were supplemented with whey on one day; whey was exchanged for lean ham and lactose on another day. Venous blood samples were drawn before and during 4 h after breakfast and 3 h after lunch for the measurement of blood glucose, serum insulin, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide 1 (GLP-1).

Results: The insulin responses were higher after both breakfast (31%) and lunch (57%) when whey was included in the meal than when whey was not included. After lunch, the blood glucose response was significantly reduced [-21%; 120 min area under the curve (AUC)] after whey ingestion. Postprandial GIP responses were higher after whey ingestion, whereas no differences were found in GLP-1 between the reference and test meals.

Conclusions: It can be concluded that the addition of whey to meals with rapidly digested and absorbed carbohydrates stimulates insulin release and reduces postprandial blood glucose excursion after a lunch meal consisting of mashed potatoes and meatballs in type 2 diabetic subjects.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Area Under Curve
  • Blood Glucose / drug effects*
  • Diabetes Mellitus, Type 2 / diet therapy*
  • Dietary Proteins / administration & dosage
  • Dietary Proteins / therapeutic use*
  • Female
  • Gastric Inhibitory Polypeptide / blood*
  • Gastric Inhibitory Polypeptide / pharmacokinetics
  • Glucagon / blood*
  • Glucagon / pharmacokinetics
  • Glucagon-Like Peptide 1
  • Glycemic Index
  • Humans
  • Insulin / blood*
  • Insulin / metabolism
  • Insulin / pharmacokinetics
  • Insulin Secretion
  • Male
  • Middle Aged
  • Milk Proteins / administration & dosage
  • Milk Proteins / therapeutic use*
  • Peptide Fragments / blood*
  • Peptide Fragments / pharmacokinetics
  • Postprandial Period
  • Protein Precursors / blood*
  • Protein Precursors / pharmacokinetics
  • Whey Proteins


  • Blood Glucose
  • Dietary Proteins
  • Insulin
  • Milk Proteins
  • Peptide Fragments
  • Protein Precursors
  • Whey Proteins
  • Gastric Inhibitory Polypeptide
  • Glucagon-Like Peptide 1
  • Glucagon