Volume 30, Issue 172, June 2026

Gut microbiota and insulin resistance - mechanisms and clinical evidence: A review of biological mechanisms, as well as observational and interventional evidence

Natalia Kursa^1♦, Katarzyna Bielak², Adam Brożyna³, Agnieszka Mackiewicz⁴, Julia Witkowska⁵, Krystian Woźniak⁶, Ksenia Jakubiak⁷, Mikołaj Kurczyński⁸, Monika Krasoń⁹, Aleksandra Pietrucień¹⁰

¹Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
²5 Military Clinical Hospital in Cracow, 30-901 Cracow, ul. Wrocławska 1-3, PL
³University Clinical Hospital No. 1 of the Medical University of Lodz: Łódź, 90-153, ul. Kopcińskiego 22, PL
⁴Medical Centre of Pabianice, Pabianice, 95-200, ul. Jana Pawła II 68, PL
⁵Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
⁶Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
⁷Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
⁸Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
⁹Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
¹⁰Medical Centre of Pabianice: Pabianice, 95-200, ul. Jana Pawła II 68, PL

^♦Corresponding author
Natalia Kursa, Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL

ABSTRACT

Background: Changes in the composition and function of the gut microbiota are associated with metabolic disorders, including lowered insulin sensitivity. Simple insulin resistance indices, such as HOMA-IR and TyG, are commonly used in population studies. Objective: A synthetic presentation of the evidence linking the gut microbiota with insulin resistance, as well as a discussion of biological mechanisms and clinical implications. Methods: This is a narrative review that includes observational and cohort studies, mechanistic studies, and microbiotamodulating interventions (e.g., supplementation, fecal transplants, and dietary interventions). Studies investigating the relationships between the microbiota profile, metabolome, and HOMA-IR and TyG values were included. Results: Various studies have shown a consistent association between specific changes in the microbiome and higher HOMA-IR and TyG values. Research has also suggested that microbial metabolites can cause insulin resistance, disrupted gut barrier function, and/or endotoxemia. Preliminary microbiota-modulating interventions show improvements in metabolic parameters; however, most trials are small and short-term. Conclusions: An integrated analysis of insulin resistance and its connections to the microbiota and metabolome can help clarify mechanisms and identify possible therapeutic targets. Further long-term studies are needed.

Keywords: gut microbiota; insulin resistance; HOMA-IR; TyG index; metabolomics; fecal microbiota transplantation

Medical Science, 2026, 30, e94ms3877

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Published: 03 June 2026