The Effect of Nutritional Interventions on Glycemic Control in Adults with Type 2 Diabetes: A Systematic Review and Meta-Analysis

Abstract

Background: Nutritional therapy is an important component of type 2 diabetes mellitus (T2DM) management; however, the magnitude of its effect on glycemic control varies across dietary approaches. This systematic review and meta-analysis evaluated the effects of nutritional interventions on glycemic outcomes in adults with T2DM.
Methods: PubMed, Scopus, Web of Science, Embase, and Cochrane CENTRAL were searched for randomized controlled trials evaluating structured nutritional interventions in adults with T2DM. Of 2,684 records identified, 721 duplicates were removed and 1,963 titles and abstracts were screened. After full-text assessment of 192 articles, 36 studies involving 5,842 participants met the inclusion criteria. Random-effects meta-analyses were conducted, with glycated hemoglobin (HbA1c) as the primary outcome. Risk of bias was assessed using Cochrane RoB 2.
Results: Nutritional interventions significantly reduced HbA1c compared with control conditions (mean difference [MD] −0.39%, 95% CI −0.50 to −0.28; I²=78%). Significant improvements were also observed in fasting plasma glucose (MD −0.62 mmol/L, 95% CI −0.86 to −0.38) and body weight (MD −2.31 kg, 95% CI −3.18 to −1.44). Greater HbA1c reductions were observed in interventions lasting ≥24 weeks and those involving individualized nutrition counseling.
Conclusion: Structured nutritional interventions can improve glycemic control and related metabolic outcomes in adults with T2DM. Individualized and sustained interventions may provide greater benefits.