For Diabetes, Low-Glycemic Diets May Be Better Than Low Glycemic Load Diets

Diets with a low glycemic index (GI) and glycemic load (GL) may improve risk factors in patients with diabetes, according to the results of a recent study.

This systematic review and meta-analysis of 29 randomized controlled trials was conducted to better evaluate the relationship between nutrition and cardiometabolic factors in adults with both type 1 and type 2 diabetes.

Included were 1617 participants who were middle-aged, overweight, or obese.

Participants were required to have type 1 or type 2 diabetes that was being moderately controlled by hyperglycemia medication or insulin.

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) method was utilized by 2 independent reviewers to measure the certainty of evidence.

Glycated hemoglobin A1c (HbA1c) was the primary outcome. Secondary outcomes included glycemic control (fasting glucose and fasting insulin), blood lipids (low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), non-HDL-C, apo B, triglycerides), adiposity (body weight, body mass index [BMI]), waist circumference), blood pressure (systolic blood pressure (SBP), diastolic blood pressure (DBP)), and inflammation (C-reactive protein (CRP)).

When compared with higher GI/GL control diets, diets with low GI/GL were associated with decreased HbA1C, fasting glucose, LDL-C, non-HDL-C, apo B, triglycerides, body weight, BMI, and CRP. However, there were no reductions in blood insulin, HDL-C, waist circumference, and blood pressure among those with low GI/GL dietary patterns.

The results also showed a positive dose response for the difference in GL and HbA1c, as well as absolute dietary GI and SBP.

The primary outcome’s certainty of evidence was high, while the secondary outcome’s certainty of evidence was moderate. Limitations include imprecision for the certainty of evidence.

“This synthesis suggests that low GI/GL dietary patterns result in small important improvements in established targets of glycemic control, blood lipids, adiposity, and inflammation beyond concurrent treatment with hyperglycemia drugs or insulin, predominantly in adults with moderately controlled type 1 and type 2 diabetes,” the researchers concluded. “The available evidence provides a good indication of the likely benefit in this population.”

—Leigh Precopio

Reference:

Chiavaroli L, Lee D, Ahmed A, et al. Effect of low glycaemic index or load dietary patterns on glycaemic control and cardiometabolic risk factors in diabetes: systematic review and meta-analysis of randomized controlled trials. BMJ. 2021;364:n1651. https://doi.org/10.1136/bmj.n1651