Evidence Hub

Citrus flavonoid supplement enhances glycemic and metabolic control in prediabetic patients on metformin: a randomized controlled trial

Thais Cesar, Maria Rita M. Oliveira, V. Sandrim, Adriana Mendes, Ricardo M. Bruder, R. Oliveira, K. Sivieri, Dragan Milenkovic

Frontiers in Nutrition, 2025

13 citations

Abstract

Background and objective Combining natural compounds with conventional drugs is an emerging strategy to improve the management of type 2 diabetes and its precursor, prediabetes. While metformin effectively lowers blood glucose and improves insulin sensitivity, it may cause side effects or lose efficacy over time. Natural agents, particularly polyphenols, are being explored as adjunct therapies to enhance glycemic control, mitigate adverse effects, and slow disease progression. This study evaluated the efficacy of a citrus bioflavonoid-based nutraceutical as an adjunct to metformin therapy in prediabetic individuals, with a focus on metabolic, inflammatory, oxidative, hormonal, and nutritional-clinical outcomes. Methods In this 12-week randomized, double-blind, placebo-controlled trial, participants received either metformin plus the citrus flavonoid supplement (250 mg/day) or metformin plus placebo. Results At the end of the intervention, the nutraceutical group demonstrated improved postprandial glucose metabolism, including a 5% reduction in 2-h OGTT glucose and preservation of active GLP-1 levels. In contrast, the placebo group exhibited a decline in GLP-1 and increased insulin resistance. Supplementation also resulted in a 12% reduction in TNF-α, a 7.5% increase in plasma antioxidant capacity (FRAP), and modest but significant decreases in body weight, fat mass, and BMI (all p ≤ 0.05). Additionally, systolic blood pressure was reduced by 4%, potentially associated with…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

Read the paper

Related studies

Go deeper in Evidence Hub

Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.

Open this study Sign up free