Gelatinisation and milling whole-wheat increases postprandial blood glucose: randomised crossover study of adults with type 2 diabetes

Abstract

Aims/hypotheses: We examined the effects of milling and cooking whole grains in water to achieve starch gelatinisation on postprandial blood glucose using a randomised crossover open-label design. Participants were adults with type 2 diabetes whose body weight or medications had not changed in at least 3 months. Methods: Postprandial blood glucose (measured as incremental AUC [iAUC]) was measured following consumption of four nutrient-matched whole-wheat porridge test-meals. Test-meals included gelatinised or native starch and were made with either finely milled or intact whole-wheat. Results: Eighteen adults (63.1 ± 9.8 years, HbA1c 57.0 ± 11.5 mmol/mol [7.4 ± 3.2%]) completed the study. iAUC was higher following cooked meals (gelatinised starch) than following uncooked meals (native starch) (mean difference [MD] 268, 95% CI 188, 348 mmol/l × min). Consuming finely milled whole-wheat produced a higher iAUC compared with intact whole-wheat (MD 173, 95% CI 80, 266 mmol/l × min). There was no evidence of an interaction effect (p = 0.841). Conclusions: Both the nature of starch and the grain structure of whole-wheat influence the glycaemic response of adults with type 2 diabetes mellitus. Funding: Baking Industry Research Trust of New Zealand and the Riddet Centre of Research Excellence. Trial registration: www.anzctr.org.au ACTRN12617000328370 Graphical abstract: [Figure not available: see fulltext.]