A whole‐grain diet increases glucose‐stimulated insulin secretion independent of gut hormones in adults at risk for type 2 diabetes

SK Malin, EL Kullman, AR Scelsi… - Molecular nutrition & …, 2019 - Wiley Online Library
SK Malin, EL Kullman, AR Scelsi, JP Godin, AB Ross, JP Kirwan
Molecular nutrition & food research, 2019Wiley Online Library
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 …
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‐peptide0‐240/Glc0‐240, 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.
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