Table 1.

Summary of study characteristics for included randomized controlled trials.

Author/date	Study design	Sample size, N	Population characteristics	Theory/model	Intervention participants, N, program name, digital intervention characteristics	Type of diets prescribed	Intervention/follow-up period
Ramadas et al, 2018 [29]	RCTa	128	Adults with T2DMb, mean age 50.5 years, most with a family history of T2DM. Malaysia	Transtheoretical Model Stages of Change, user-centered design	N=62, myDIDeAc, received personalized intensive dietary intervention via website + standard care	IGd: standard dietary guidelines CGe: no prescribed diet	6-month intervention, 12-month follow-up
Hansel et al, 2017 [28]	RCT	120	Adults with abdominal obesity and T2DM, mean age 57 years. Paris	No theory reported	N=60, ANODEf, fully automated web-based nutritional support program	IG: National Nutrition & Health Program guidelines CG: received general diet advice	16-week intervention
Saslow et al, 2017 [30]	Pilot RCT	25	Overweight adults with T2DM, mean age 55.6 years. California	No theory reported	N=12, dietary instruction provided via email lessons including mindfulness training and lifestyle advice	IG: VLKCDg (20-50 g/carbs per day) CG: ADAh “create your plate” diet	16-week intervention, 32-week follow-up
Glasgow et al, 2003 [31]	RCT	320	Adults with T2DM, mean age 59 years. Colorado	Self-efficacy theory, social support theory	N=N/Ai, D-Netj, two intervention arms: tailored self-management training, peer support	All groups received general healthy eating advice to decrease fat and increase fruit and vegetable intake	3-month intervention, 10-month follow-up
Glasgow et al, 2012 [32]	RCT	463	Adults with T2DM, mean age 58.4 years. Colorado	Social-ecological theory, social cognitive theory and the “5 As” self-management model	N=189, two intervention arms: CASMk: self-administered computer-assisted self-management; N=182, CASM+l with enhanced social support	All groups received general advice to decrease fat and eat a healthy diet	4-month intervention, 12-month follow-up

^aRCT: randomized controlled trial.

^bT2DM: type 2 diabetes mellitus.

^cmyDIDeA: Malaysian Dietary Intervention for People with Type 2 Diabetes: An e-Approach.

^dIG: intervention group.

^eCG: control group.

^fANODE: Accompagnement Nutritionnel de l’Obésité et du Diabète par E­coaching.

^gVLCKD: very low carbohydrate ketogenic diet.

^hADA: American Diabetes Association.

ⁱN/A: not applicable.

^jD-Net: Diabetes Network.

^kCASM: computer-assisted self-management.

^lCASM+: computer-assisted self-management plus social support.