The goal of a new study published in Molecular Nutrition & Food Research was to ascertain the effect of whole-grain (WG) versus refined-grain (RG) diets on glucose-stimulated insulin secretion (GSIS) and β-cell function.

This was a double-blinded, crossover, randomized controlled trial, wherein 13 prediabetic adults were provided with isocaloric-matched WG and RG diets for eight weeks each, with an 8-10 week washout between diets. Glucose, insulin, and C-peptide of the participants were studied over 240 mins following a 75 g OGTT. Incretins (GLP-1 and GIP), PYY, and total ghrelin were assessed at 0, 30, and 60 mins.

The results showed that both diets induced fat loss of about 2 kgs. Neither diets impacted early phase GSIS, yet the WG diet increased the total GSIS and β-cell function in this population. Additionally, GIP and PYY were unaltered by either diet, but GLP-1 was higher at 30 mins following RG, than with WG. On the other hand, ghrelin levels were higher at 60 min of the OGTT following both interventions.

From the findings, it was inferred that a WG-rich diet increases β-cell function independent of gut hormones in adults with prediabetes.