The Effect of Low Glycemic Index/Load Dietary Patterns on Glycemic Control and Cardiometabolic Risk Factors in Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Laura Chiavaroli, Coauthor, University of TorontoJohn SievenpiperPresenting Author

Danielle Lee, Coauthor, University of TorontoJohn Sievenpiper

Amna Ahmed, Coauthor, University of TorontoJohn Sievenpiper

Annette Cheung, Coauthor, University of Toronto

Tauseef Khan, Coauthor, University of TorontoJohn Sievenpiper

Sonia Blanco Mejia, Coauthor, University of Toronto

Arash Mirrahimi, Coauthor, University of Toronto

David Jenkins, Coauthor, University of Toronto

Geoffrey Livesey, Coauthor, Independent Nutrition Logic Ltd

Thomas Wolever, Coauthor, INQUIS Clinical Research, Ltd

Dario Rahelić, Coauthor, Merkur University Hospital

Hana Kahleová, Coauthor, Institute for Clinical and Experimental Medicine, Diabetes Centre

Jordi Salas-Salvadó, Coauthor, Universitat Rovira i Virgili

Cyril Kendall, Coauthor, University of Toronto

John Sievenpiper, Coauthor, University of Toronto

Background: Low-glycemic index (GI) and load (GL) dietary patterns are recommended for diabetes management by clinical practice guidelines globally. To inform the update of the European Association for the Study of Diabetes (EASD) clinical practice guidelines for nutrition therapy, we conducted a systematic review and meta-analysis on the effect of low-GI/GL dietary patterns on glycemic control and other established cardiometabolic risk factors in type 1 and 2 diabetes.

Methods: MEDLINE, EMBASE, and the Cochrane Library were searched through November 2020. We included randomized controlled trials ≥3-weeks investigating the effect of low-GI/GL diets in diabetes. The primary outcome was HbA1c. Two independent reviewers extracted data and assessed risk of bias. GRADE (grading of recommendations assessment, development, and evaluation) assessed the certainty of the evidence. (ClinicalTrials.gov identifier, NCT04045938)

Findings: We identified 30 trial comparisons in 1,672 participants with type 1 and 2 diabetes who were predominantly middle-aged, overweight or obese with moderately controlled type 2 diabetes treated by antihyperglycemic agents and/or insulin. Low-GI/GL dietary patterns significantly reduced HbA1c compared with higher-GI/GL control diets (mean difference -0.32% [95% confidence interval -0.48, -0.16%], P<0.001; substantial heterogeneity, I2=74%, P<0.001). There were also significant reductions in several secondary outcomes: fasting glucose, LDL-C, non-HDL-C, body weight, BMI, and CRP (P<0.05), but not insulin or blood pressure. The certainty of evidence was moderate for the reduction in HbA1c and most secondary outcomes.

Interpretation: Our synthesis indicates that low-GI/GL dietary patterns improve established targets of glycemic control, blood lipids, adiposity and inflammation beyond concurrent therapy with antihyperglycemic agents and/or insulin in moderately controlled type 1 and type 2 diabetes. The available evidence provides a good indication of the likely benefit in this population with moderate likelihood that more research will alter our conclusions.

Main Funding Sources: Diabetes and Nutrition Study Group of the EASD, CIHR