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. 2025 Apr 28:83:103222.
doi: 10.1016/j.eclinm.2025.103222. eCollection 2025 May.

Effects of different dietary patterns on glucose management in type 1 diabetes: a systematic review and meta-analysis of randomized controlled trials

Jiayi Zeng  1   2 , Miranda Beck  1 , Afroditi Alexandra Barouti  3   4 , Josefin E Löfvenborg  5 , Sofia Carlsson  1 , Anna-Maria Lampousi  1   6
Affiliations

Effects of different dietary patterns on glucose management in type 1 diabetes: a systematic review and meta-analysis of randomized controlled trials

Jiayi Zeng et al. EClinicalMedicine. .

Abstract

Background: Effective glucose management is essential to prevent complications in type 1 diabetes. While nutrition therapy is crucial, the optimal diet remains uncertain. Our systematic review and meta-analysis synthesized evidence from randomized controlled trials (RCTs) on the impact of various diets on glucose management in type 1 diabetes.

Methods: We systematically searched Medline, Embase, and Cochrane Library up to 11 November 2024 for RCTs on dietary patterns and glucose control outcomes in type 1 diabetes, including HbA1c, time in range (TIR), coefficient of variation (CV), hypoglycemia, insulin dose, and anthropometric characteristics. Two reviewers independently extracted data and assessed the risk of bias using the RoB-2 tool. We estimated summary mean differences (MD) with 95% CIs using random-effects models. The certainty of the evidence was evaluated using GRADE. The study protocol was registered in PROSPERO (CRD42023479252).

Findings: Out of 5287 studies, 35 RCTs involving children, adolescents, and adults with type 1 diabetes were eligible. Higher-fiber diets (≥35 g/day, 5 RCTs) reduced HbA1c (MD -0.46%, 95% CI -0.93 to 0.00, I2 65%) and hypoglycemia (MD -0.81 episodes/month, 95% CI -1.34 to -0.28, I2 0%), with moderate and low certainty of evidence, respectively. Carbohydrate-restricted diets (≤45% energy, 20 RCTs) improved TIR (MD 3.84%, 95% CI 2.24-5.44, I2 0%), CV (MD -3.24%, 95% CI -5.51 to -0.97, I2 53%), and insulin needs (MD -5.63 U/day, 95% CI -9.51 to -1.74, I2 70%), but not HbA1c, with low to moderate certainty of evidence. Higher-protein, low-glycemic index, gluten-free, Mediterranean, vegan, and intermittent fasting diets showed no effects on glucose management (1-6 RCTs), although certainty of evidence was low.

Interpretation: Maintaining a high-fiber diet while restricting other carbohydrates may improve glycemic control in individuals with type 1 diabetes. Further investigation is needed into long-term effects and other diets.

Funding: Swedish Research Council, Swedish Diabetes Foundation, and the Strategic Research Programme in Diabetes at Karolinska Institutet.

Keywords: Dietary patterns; Glucose management; Meta-analysis; Randomized controlled trials; Type 1 diabetes.

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Conflict of interest statement

AB has a consulting agreement with Abbott Scandinavia AB for the development of a digital program focusing on diet in people with type 2 diabetes, starting on March 26, 2025. This agreement does not pertain to the current manuscript.

Figures

Fig. 1
Fig. 1
Flow diagram of study selection.
Fig. 2
Fig. 2
Summary mean differences with 95% confidence intervals for each dietary pattern comparison.
See this image and copyright information in PMC

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