Food 4 Health - He Oranga Kai: Assessing the efficacy, acceptability and economic implications of Lactobacillus rhamnosus HN001 and β-glucan to improve glycated haemoglobin, metabolic health, and general well-being in adults with pre-diabetes: study protocol for a 2 × 2 factorial design, parallel group, placebo-controlled randomized controlled trial, with embedded qualitative study and economic analysis

Background The rates of pre-diabetes and type 2 diabetes mellitus are increasing worldwide, producing significant burdens for individuals, families, and healthcare systems. In New Zealand, type 2 diabetes mellitus and pre-diabetes disproportionally affect Māori, Pacific, and South Asian peoples. This research evaluates the efficacy, acceptability, and economic impact of a probiotic capsule and a prebiotic cereal intervention in adults with pre-diabetes on metabolic and mental health and well-being outcomes.