Comparative effects of different macronutrient compositions for type 2 diabetes management: a systematic review and network meta-analysis of randomized trials.

Abstract

Background: To assess and rank the comparative effects of different exact macronutrient compositions for type 2 diabetes management rather than examining single macronutrients or as a dietary pattern.

Methods: PubMed, Scopus, and Cochrane Library Central Register of Controlled Trials were searched. Randomized controlled trials were included. A random-effects network meta-analysis with a Bayesian framework was performed to calculate the mean difference (MD) and 95% credible intervals (CrIs). The certainty of evidence was rated using the GRADE approach.

Results: 80 trials with 9232 patients with type 2 diabetes were included in the network meta-analysis. A very low-carbohydrate, high-protein, and calorie-restricted diet had the greatest effect on reducing HbA_1c (range of mean difference: - 1.0% to - 1.79%), weight (range of mean difference: -5.83 kg to -10.96 kg), and FPG (range of mean difference: - 2.20 mmol/L to - 2.88 mmol/L) at 6-month follow-up, but at 12-month follow-up, the effect remained only for HbA_1c (range of mean difference: - 1.25% to - 1.30%) and FPG (range of mean difference: - 1.21 mmol/L to - 1.27 mmol/L). For weight loss in 12-month follow-up, the low-carbohydrate, high-protein diet was probably the most effective approach (range of mean difference: - 10.05 kg to - 14.52 kg). The best dietary approach to reduce LDL at 6-month follow-up was a low carbohydrate, high protein, calorie-restricted diet (range of mean difference: - 0.49 mmol/L to - 0.59 mmol/L) and at 12-month follow-up, a moderate carbohydrate, standard protein, calorie-restricted diet was effective in reducing LDL (mean difference: - 0.87 mmol/L, 95%CrI - 1.55 to - 0.16).

Conclusions: A very low carbohydrate, high protein, calorie-restricted diet can be an effective dietary composition in managing diabetes, but milder dietary carbohydrate restriction for weight loss in the long-term, and improving lipid profiles is needed.