A network meta-analysis on the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus

Abstract

The aim of the present study is to assess the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus using a systematic review of the literature. Electronic and hand searches were performed until July 2017. The inclusion criteria were defined as follows: (1) randomized trial with a dietary approach; (2) adults with type 2 diabetes mellitus; (3) outcome either HbA1c (%) and/or fasting glucose (mmol/l); (4) minimum intervention period of 12 weeks. For each outcome measure, random effects network meta-analysis was performed in order to determine the pooled effect of each intervention relative to each of the other interventions. A total of 56 trials comparing nine dietary approaches (low-fat, Vegetarian, Mediterranean, high-protein, moderate-carbohydrate, low-carbohydrate, control, low GI/GL, Palaeolithic) enrolling 4937 participants were included. For reducing HbA1c, the low-carbohydrate diet was ranked as the best dietary approach (SUCRA: 84%), followed by the Mediterranean diet (80%) and Palaeolithic diet (76%) compared to a control diet. For reducing fasting glucose, the Mediterranean diet (88%) was ranked as the best approach, followed by Palaeolithic diet (71%) and Vegetarian diet (63%). The network analysis also revealed that all dietary approaches significantly reduce HbA1c (- 0.82 to - 0.47% reduction) and fasting glucose (- 1.61 to - 1.00 mmol/l reduction) compared to a control diet. According to the network meta-analysis the Mediterranean diet is the most effective and efficacious dietary approach to improve glycaemic control in type 2 diabetes patients.

Keywords: Diet; Evidence synthesis; Network meta-analysis; Systematic review; Type 2 diabetes mellitus.

Fig. 1

Example of direct, indirect and mixed relative effects in a hypothetical triangle comparing three interventions

Fig. 2

Network diagram for HbA1c: The size of the nodes is proportional to the total number of participants allocated to each dietary approach and the thickness of the lines proportional to the number of studies evaluating each direct comparison