Effects of Whole Grain Intake, Compared to Refined Grain, on Glycemia and Insulinemia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Open accessAbstract
Epidemiological study results suggest that whole grain (WG) consumption is associated with a reduced risk of type 2 diabetes; however, the potential mechanism behind this observation is unclear. WG intake may lower postprandial glycemia and insulinemia and improve insulin sensitivity, thereby contributing to a reduced risk of type 2 diabetes. The objective of this systematic review and meta-analysis was to evaluate the impact of WG on postprandial glycemia and insulinemia and markers of glycemic control and insulin sensitivity/resistance. A systematic review and meta-analysis was conducted on randomized controlled trials (RCTs) evaluating the effect of WG intake, compared to refined grain (RG) intake, on postprandial glycemia and insulinemia area under the curve and markers of glycemic control and insulin sensitivity/resistance in adults. A search of PubMed and Scopus yielded 80 relevant RCTs. Pooled estimates were expressed as standardized mean differences (SMD) between the WG intervention and RG control group. WG intake resulted in a significant reduction of postprandial glycemia (SMD: −0.46, 95% CI: −0.59, −0.33, P < 0.001) and insulinemia (SMD: −0.29, 95% CI: −0.39, −0.20, P < 0.001), compared to RG intake. There were no significant effects of WG on fasting glucose, fasting insulin, or homeostatic model assessment of insulin resistance (HOMA-IR); however, there was a marginally significant benefit of WG intake for glycated hemoglobin (HbA1c) (P = 0.050). Compared to RG foods, WG foods improve postprandial glycemia and insulinemia which may partially explain the association of WG intake and reduced risk of type 2 diabetes. However, WG intake did not impact long-term markers of glycemic and insulinemic control, except for a marginally significant effect on HbA1c. While short term improvements in glycemic response may be beneficial, more investigations are needed to determine if these lead to long-term benefits in reducing the risk of type 2 diabetes. PROSPERO Registration: CRD42020180069 This research was funded by General Mills, Inc.
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Carbohydrate-rich foods that may be more effective in ameliorating postprandial hyperglycemia and IR include legumes/pulses, whole grains, and pasta.
“Carbohydrate-rich foods that may be more effective in ameliorating postprandial hyperglycemia and IR include legumes/pulses [85,86,87], whole grains [88,89,90,91], and pasta [92].”
From Effects of diet, lifestyle, Chrononutrition and alternative dietary interventions on postprandial Glycemia and insulin resistance (2022) · cites this paper as [91]
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Papakonstantinou, E., Oikonomou, C., Nychas, G., & Dimitriadis, G. D. (2022) · Nutrients · doi:10.3390/nu14040823 · Cited by 199 · see citing works
Jayedi, A., Ge, L., Johnston, B. C., Shahinfar, H., Safabakhsh, M., Mohamadpur, S., Ghorbaninejad, P., Abyadeh, M., Zeraattalab-Motlagh, S., Soltani, S., et al. (2022) · European Journal of Nutrition · doi:10.1007/s00394-022-03046-z · Cited by 15 · see citing works
Čad, E. M., Bolha, A., Ferjančič, B., et al. (2026) · Nutrients · doi:10.3390/nu18060896 · Cited by 1 · see citing works
“Whole-grain foods, which are higher in dietary fiber and micronutrients compared to their refined counterparts, are associated with improved long-term health outcomes and offer environmental benefits due to their lower degree of processing [14–16].”
Song, J., & Jian, F. (2026) · Journal of Functional Foods · doi:10.1016/j.jff.2026.107297
- Authors
- Sanders, L., Zhu, Y., Wilcox, M., Koecher, K., & Maki, K.
- Affiliations
- General Mills (United States) (US)
- Indiana University (US)
- Venue
- Current Developments in Nutrition
- Publisher
- Elsevier BV
- Published
- 2021-06
- Volume
- 5
- Pages
- 521
- ISSN
- 2475-2991 (ISSN-L)
- PMC
- PMC8182092
- OpenAlex
- W3168891624
- Cited by
- 4
- References
- 0
- Citations by year
- 2026: 2 · 2022: 2
- FWCI
- 0.07
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Current Developments in Nutrition (publishedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion)
- Topics
- Health Sciences › Nursing › Nutrition and Dietetics › Food composition and properties
- Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Nutritional Studies and Diet
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Natural Antidiabetic Agents Studies
- Keywords
- whole grains, refined grains, postprandial blood glucose, insulin levels, insulin sensitivity, insulin resistance, HbA1c, type 2 diabetes risk, glycemic control, dietary fiber
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