Low-Carbohydrate Dietary Interventions for Metabolic Control in Individuals With Type 2 Diabetes Mellitus: An Overview of Systematic Reviews

Abstract

Context: Dietary interventions providing different amounts of carbohydrates have been proposed as a means of achieving glycemic control and weight loss in type 2 diabetes mellitus (T2DM); however, the supporting evidence is heterogeneous, making this recommendation difficult to apply in nutritional clinical practice.

Objective: The aim was to assess the quality of evidence from meta-analyses on low-carbohydrate (LC) dietary interventions for glycemic control, weight loss, and lipid profile in individuals with T2DM.

Data sources: The MEDLINE, Web of Science, and Scopus databases were searched until September 2023.

Data extraction: A systematic review was conducted. Systematic reviews with meta-analysis of randomized clinical trials designed to assess glycated hemoglobin (HbA1c) reductions in individuals with T2DM were eligible. The AMSTAR-2 critical appraisal tool was used to evaluate the methodological aspects of all included studies. The GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach was used to assess the certainty of the evidence.

Data analysis: The LC interventions were associated with a reduction in HbA1c (%) of -0.42 (-1.45 to -0.09; high certainty of evidence) without considering follow-up time; at up to 3 months of follow-up of -0.28 (-0.13 to -0.43); at up to 6 months of follow-up of -0.40 (-0.61 to -0.09); at 6 to 12 months of follow-up of -0.32 (-0.49 to 0.11); and at >12 months of follow-up time of -0.31 (-0.14 to -0.65) compared with control diets.

Conclusion: LC diets can help reduce HbA1c in individuals with T2DM in the short term (up to 3 months). However, dietary recommendations must always be individualized, as the studies reviewed herein analyzed different populations and used different definitions of what constitutes an LC diet.

Systematic review registration: PROSPERO no. CRD42023404197.

Keywords: blood glucose; glycated hemoglobin; low-carbohydrate diet; type 2 diabetes mellitus.