Does inulin supplementation improve glucose metabolism and reduce the risk of type 2 diabetes in adults at elevated risk?
Inulin, a randomized controlled trial in 24, participants (Nutrients 2021, PMID 34579112) — fasting insulin concentrations showed a reduction with inulin (Δ-2.9) compared to an increase with placebo (Δ2.3), but this was attenuated after adjusting for baseline differences. Despite these changes, inulin supplementation did not improve peripheral insulin sensitivity.
Source: Nutrients 2021, PMID 34579112 ↗ · Research map · How Magellan grades evidence · evidence confidence: high
Nutrients · 2021 · PMID 34579112
Inulin supplementation did not improve peripheral insulin sensitivity in adults at risk for type 2 diabetes.
The question
Does inulin supplementation improve glucose metabolism and reduce the risk of type 2 diabetes in adults at elevated risk?
What they tested
The study aimed to determine the efficacy of inulin supplementation to improve glucose metabolism and reduce type 2 diabetes risk.
How they did it
Adults at risk for type 2 diabetes (n=24, BMI: 31.3 ± 2.9 kg/m², age: 54.4 ± 8.3 years) were enrolled in a 6-week controlled feeding trial. Participants consumed either 10 g/day of inulin or 10 g/day of maltodextrin (placebo). Assessments included peripheral insulin sensitivity, fasting glucose, insulin, HOMA-IR, in vivo skeletal muscle substrate preference, copy number, intestinal permeability, and endotoxin concentrations.
What they found
Participant retention was 92%. Fasting insulin concentrations showed a reduction with inulin (Δ-2.9) compared to an increase with placebo (Δ2.3), but this was attenuated after adjusting for baseline differences. HOMA-IR reduction with inulin (Δ-0.40) remained significant after adjusting for baseline values, compared to an increase with placebo (Δ0.27). Gut 16s increased with inulin supplementation (Δ3.1e) and decreased with placebo (Δ-8.9e). Despite these changes, inulin supplementation did not improve peripheral insulin sensitivity.
| Fasting Insulin (Inulin) | -2.9 | |
|---|---|---|
| Fasting Insulin (Placebo) | 2.3 | |
| HOMA-IR (Inulin) | -0.4 | |
| HOMA-IR (Placebo) | 0.27 |
Changes in fasting insulin and HOMA-IR after six weeks of inulin or placebo supplementation. Negative values indicate a reduction, positive values indicate an increase.
What it means
Inulin supplementation did not improve peripheral insulin sensitivity in adults at elevated risk for type 2 diabetes, despite some observed changes in fasting insulin, HOMA-IR, and gut 16s. These findings suggest that larger investigations into inulin and insulin sensitivity in this population may not be warranted.
Limitations
The study was a pilot trial with a small sample size. There was a baseline difference in fasting insulin between the groups.
The paper at a glance
| Title | Prebiotic Inulin Supplementation and Peripheral Insulin Sensitivity in adults at Elevated Risk for Type 2 Diabetes: A Pilot Randomized Controlled Trial |
|---|---|
| Journal | Nutrients |
| Year | 2021 |
| PMID | 34579112 ↗ |
| Topic | Metabolic health, glucose & body composition |
| DOI | Not recorded in our database — use the PubMed record above. |
Read the source: PubMed record (authors, abstract, full citation) ↗
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Inulin (Prebiotic Fiber)
Randomized trials and meta-analyses indicate that inulin-type fructans reliably increase stool frequency and improve constipation (confirmed again in a 2025 trial using 12 g/day), selectively feed beneficial gut bacteria, and can enhance calcium absorption.
Inulin is a group of naturally occurring polysaccharides known as fructans (chains of fructose…
Research describes the compound or intervention studied. It is not a claim about any specific product.
Molecules & mechanisms in this paper
Each of these is named in the paper’s own words above. Open the monograph for the full mechanism and its other citations.
Cite this page
These citations point at this summary. To cite the original paper with its full author list, use the PubMed record.
Magellan Longevity. (2026). Does inulin supplementation improve glucose metabolism and reduce the risk of type 2 diabetes in adults at elevated risk? [Plain-English summary of Nutrients 2021, PMID 34579112]. Magellan Longevity. https://magellanlongevity.com/study/inulin_rct.html@misc{magellan_inulin_rct,
title = {Does inulin supplementation improve glucose metabolism and reduce the risk of type 2 diabetes in adults at elevated risk?},
author = {{Magellan Longevity}},
year = {2026},
howpublished = {\url{https://magellanlongevity.com/study/inulin_rct.html}},
note = {Plain-English summary of PubMed PMID 34579112; Nutrients 2021. Reviewed by Gabriel Radu, DO},
urldate = {2026-08-11}
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