Supplements · Diets · Metabolic & Cardiometabolic
inulin-type fructans decreases fasting glucose
In plain terms: Does inulin fibre lower fasting blood sugar?
Part of: 🧪 inulin-type fructans
Yes, modestly, but only in people who already have type 2 diabetes, not in healthy people.
📅 Last reviewed: 2026-07-15 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
What the evidence shows
Inulin-type fructans lower fasting glucose (-0.42 mmol/L) only in people with T2D; effect is null in healthy/overweight-only groups — a conditional, not general, glucose claim.
The evidence (15)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Liu F, Prabhakar M, Ju J, Long H, Zhou HW 2017 · Eur J Clin Nutr | meta-analysis | supports | moderate | ITF meta-analysis: glucose control improvement demonstrated in the type-2 diabetes subgroup; LDL benefit across populations. |
| inulin-t2d-2019 2019 · Journal of translational medicine | meta-analysis | supports | high | GRADE dose-response MA of 33 RCTs: inulin-type fructans improve glycemic control incl fasting glucose in prediabetes/T2D |
| Cai X, Yu H, Liu L, Lu T, Li J, Ji Y, Le Z, Bao L, Ma W, Xiao R, Yang Y 2018 · Mol Nutr Food Res | RCT | supports | moderate | Milk powder co-supplemented with inulin+resistant dextrin lowered fasting glucose ~0.96 mmol/L and HOMA-IR in T2DM. |
| Li L, Li P, Xu L 2021 · Food Sci Nutr | meta-analysis | supports | moderate | FBG WMD -0.42 mmol/L in diabetics; no effect in healthy/overweight strata |
| Bartsch M, Vital M, Woltemate S, Bouwman FG, Berkemeyer SB, Hahn A, Müller M 2025 · The Journal of nutrition | RCT | tested-null | low | 23 healthy adults, crossover, 15g/d INU vs PLA x1wk: 'Neither fiber affected glucose, insulin' (healthy population null) |
| Guess ND, Dornhorst A, Oliver N, Frost GS 2016 · Ann Nutr Metab | RCT | supports | moderate | Crossover trial: inulin improved glucose homeostasis and reduced HOMA-IR specifically in impaired-fasting-glucose prediabetes. ↩ SUPERSEDED — pooled in the review above, counted once |
| Mitchell CM, Davy BM, Ponder MA, McMillan RP, Hughes MD, Hulver MW, Neilson AP, Davy KP 2021 · Nutrients | RCT | tested-null | moderate | Pilot controlled-feeding RCT, 24 adults at elevated T2D risk but NOT diabetic (baseline FBG 87-94 mg/dL; authors: 'relatively healthy'), inulin 10 g/d vs maltodextrin x6 wk (NCT02346838). FBG did not change (inulin 94->97, placebo 87->85 mg/dL; p>0.05); peripheral insulin sensitivity (IVGTT SI, n=17) unchanged; HOMA-IR fall not robust to baseline adjustment (abstract and results disagree). Trial stopped early (effect size 0.21). Non-diabetic population sits outside the claim's T2D-only scope, where the claim itself expects a null: neutral to the claim, tested-null. |
| Dehghan P, Gargari BP, Jafar-Abadi MA, Aliasgharzadeh A 2014 · Int J Food Sci Nutr | RCT | supports | moderate | Inulin in women with T2DM cut fasting insulin and HOMA-IR (39.5%) plus inflammation/endotoxemia markers. ↩ SUPERSEDED — pooled in the review above, counted once |
| Dehghan P, Pourghassem Gargari B, Asgharijafarabadi M 2013 · Health Promot Perspect | RCT | supports | moderate | High-performance inulin in women with T2DM cut fasting blood sugar 8.5% and HbA1c 10.4% vs non-significant control. |
| Al-Juhani A, Desoky MS, Almuhaimid AA, Zaheer M, Alhaqbani HF, Abalkhail EA, Alanazi SA, Alzahrani RS, Alrefaai M, Desoky R 2025 · Cureus | observational | supports | moderate | Narrative SR of prebiotics BROADLY (not inulin-specific) reports FPG decrease in overweight; too non-specific to cleanly test inulin's T2D-only conditionality -> mixed. |
| Birkeland E, Gharagozlian S, Birkeland KI, Valeur J, Måge I, Rud I, Aas AM 2020 · Eur J Nutr | RCT | tested-null | low | ITF in T2D produced bifidogenic and SCFA increases but only moderate potential to improve metabolic outcomes; no glucose endpoint shift emphasized. |
| Juhasz 2023 · Am J Clin Nutr | meta-analysis | mixed | moderate | Network meta-analysis ranks galactomannans, not inulin, as most effective fiber for fasting glucose/HbA1c in T2D. |
| Dimba NR, Mzimela N, Sosibo AM, Khathi A 2024 · Nutrients | meta-analysis | contradicts | low | 8 RCTs, 7 in T2D/1 prediabetes: prebiotic intervention had no statistically significant effect on FBG or HbA1c |
| Dehghan P, Pourghassem Gargari B, Asghari Jafar-abadi M 2014 · Nutrition | RCT | supports | moderate | Oligofructose-enriched inulin 10g/d x8wk cut fasting glucose 9.5% vs maltodextrin in women with T2D ↩ SUPERSEDED — pooled in the review above, counted once |
| Roshanravan N, Mahdavi R, Alizadeh E, Jafarabadi MA, Hedayati M, Ghavami A, Alipour S, Alamdari NM, Barati M, Ostadrahimi A 2017 · Horm Metab Res | RCT | supports | moderate | High-performance inulin (+/-butyrate) improved glycemic status and raised GLP-1 in type-2 diabetes patients. |
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