Evidence map›Paper›PMID 41776124›Full record

ArticleDiabetologia2026

The microbial tryptophan metabolite indole acts on the gastrointestinal tract to improve glucose homeostasis in a mouse model of diabetes by enhancing GLP-1 secretion and L cell differentiation.

Phyllis Phuah, Mariana Norton, Sijing Cheng, Anna G Roberts, Daniela Pirri, Leah Meyer, Pei-En Chung, Cecilia Dunsterville, Rafal Karwowski, Brian Y H Lam and 10 more

Abstract read
In one paragraph

Article in Diabetologia, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.

0numbers the graph read from it
0cells of the map it votes in
3citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

3 citing papers in PubMed.

  1. Review
  2. The gut-joint axis in osteoarthritis.Nature reviews. Rheumatology · 2026
    Review
  3. Review
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

20 authors.

Phyllis PhuahSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Mariana NortonSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Sijing ChengMRC Metabolic Diseases Unit, Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
Anna G RobertsSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Daniela PirriSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Leah MeyerSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Pei-En ChungSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Cecilia DunstervilleSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Rafal KarwowskiSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Brian Y H LamMRC Metabolic Diseases Unit, Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
Emile OtsuboSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Sofia AleksashinaMRC Metabolic Diseases Unit, Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
Fiona M GribbleMRC Metabolic Diseases Unit, Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
Frank ReimannMRC Metabolic Diseases Unit, Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
Aylin C HanyalogluInstitute of Reproductive and Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
Giles S H YeoMRC Metabolic Diseases Unit, Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
Gavin A BewickDiabetes and Obesity Theme, School of Cardiovascular and Metabolic Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK.
Ben JonesSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Bryn OwenSection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Kevin G MurphySection of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK. k.g.murphy@imperial.ac.uk.

Funding

Biotechnology and Biological Sciences Research Council BB/S017593/1Biotechnology and Biological Sciences Research Council BB/W001497/1Biotechnology and Biological Sciences Research Council BB/X017273/1Diabetes UK 18/0005886Diabetes UK 20/0006295Medical Research Council MC_UU_00014/1Medical Research Council MC_UU_00014/5Medical Research Council MC_UU_12012/3Medical Research Council MR/X021467/1Medical Research Council MR/Y00132X/1Medical Research Council MR/Y013980/1Medical Research Council RGAG/542 MC_UU_00039Wellcome Trust 208363/Z/17/ZWellcome Trust 220271/Z/20/ZWellcome Trust 226800/Z/22/ZWellcome Trust 301619/Z/23/ZWellcome Trust 310835/Z/24/ZWellcome Trust RGAG/546
6 · The paper itself

Abstract

aims/hypothesisGrowing evidence implicates gut microbiota-derived metabolites in metabolic homeostasis. Indole, a microbial tryptophan metabolite, has been reported to enhance glucagon-like peptide-1 (GLP-1) secretion in vitro, and its derivatives have been inversely associated with risk of type 2 diabetes. We hypothesised that indole acts via the gastrointestinal tract to modulate glucose homeostasis, and tested this hypothesis using in vitro and in vivo models.

methodsWe measured GLP-1 secretion from cultured murine enteroendocrine cells, and evaluated intraperitoneal glucose tolerance and hormone secretion in mice following indole treatment. Subsequently, the impact of indole on intestinal epithelial cell fate and L cell number was examined using murine ileal organoid cultures and in vivo. Finally, we explored the effect of chronic indole administration on metabolic outcomes in a murine model of type 2 diabetes.

resultsIndole stimulated in vitro GLP-1 secretion in a concentration-dependent manner, and improved acute glucose management in vivo. Additionally, we demonstrate that indole drives enteroendocrine L cell differentiation in murine ileal organoids, resulting in increased L cell density and longer-term glucoregulatory benefits in vivo. Finally, sub-chronic indole administration improved glucose tolerance and insulin sensitivity in a diabetic mouse model. CONCLUSIONS/

interpretationOur findings identify indole as a glucose-lowering molecule that acts on the gut, and raise the possibility of incorporating indole into nutraceutical supplements to aid in the treatment or prevention of type 2 diabetes. This study highlights the importance of gut microbiota-derived metabolites in metabolic health and opens new avenues for developing novel strategies to combat type 2 diabetes. DATA AVAILABILITY: RNA sequencing data are available from the Gene Expression Omnibus under accession number GSE306720.

Indexed as

Diabetes Mellitus, ExperimentalDiabetes Mellitus, Type 2Gastrointestinal TractGlucagon-Like Peptide 1GlucoseIndolesTryptophanAnimalsBlood GlucoseCell DifferentiationEnteroendocrine CellsHomeostasisL CellsMaleMiceMice, Inbred C57BLBlood GlucoseGlucagon-Like Peptide 1GlucoseindoleIndolesTryptophanGlucagon-like peptide-1Glucose homeostasisTransient receptor potential channel subtype A1

Identifiers

PMID41776124
PMCPMC13109135

What Socratic holds

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.