A Whole-Grain Diet Increases Glucose-Stimulated Insulin Secretion Independent of Gut Hormones in Adults at Risk for Type 2 Diabetes
Journal article, 2019

Introduction: The effect of whole-grain (WG) versus refined-grain (RG) diets on glucose-stimulated insulin secretion (GSIS) and β-cell function is unclear. Methods: In a double-blind crossover randomized controlled trial, 13 prediabetic adults (37.2 ± 1.8 y, BMI: 33.6 ± 1.4 kg m −2 , 2 h glucose: 146.9 ± 11.6 mg dL −1 ) are provided isocaloric-matched WG and RG diets for 8-weeks each, with an 8–10 week washout between diets. Glucose, insulin, and C-peptide are studied over 240 min following a 75 g OGTT. Incretins (GLP-1 and GIP), PYY, and total ghrelin are assessed at 0, 30, and 60 min. Mixed-meal diets for carbohydrate (54%), fat (28%), and protein (18%) contain either WG (50 g/1000 kcal) or equivalent RG. Results: Both diets induce fat loss (≈2 kg). While neither diet impacts early phase GSIS, the WG diet increases total GSIS (iAUC of C-peptide 0-240 /Glc 0-240 , p = 0.02) and β-cell function (disposition index; GSIS × insulin sensitivity, p = 0.02). GIP and PYY are unaltered by either diet, but GLP-1 is higher at 30 min following RG versus WG (p = 0.04). Ghrelin levels are higher at 60 min of the OGTT following both interventions (p = 0.01). Conclusion: A WG-rich diet increases β-cell function independent of gut hormones in adults with prediabetes.


low-glycemic diet



glucose tolerance


Steven K Malin

University of Virginia

Cleveland Clinic Foundation

Emily L Kullman

Cleveland State University

Cleveland Clinic Foundation

Amanda R Scelsi

Cleveland Clinic Foundation

J. P. Godin

Nestle S.A.

Alastair Ross

Chalmers, Biology and Biological Engineering, Food and Nutrition Science

J.P. Kirwan

Cleveland Clinic Foundation

Pennington Biomedical Research Center

Molecular Nutrition and Food Research

1613-4125 (ISSN) 1613-4133 (eISSN)

Vol. 63 7 1800967

Subject Categories

Endocrinology and Diabetes

Other Clinical Medicine

Nutrition and Dietetics



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