Supplements, reviewed against the evidence
Inositol
Strength of evidence: Weak
Updated 2026-08-07
Short answer
Does inositol improve insulin resistance?
In women with polycystic ovary syndrome, an umbrella review of meta-analyses found inositol improved fasting insulin with moderate certainty, and increased ovulation rates in those who were subfertile. That is a real finding in a defined group. There is no comparable evidence base for inositol as a general glucose supplement.
Before you take this
Talk to your prescriber before adding this to any medication, especially anything that lowers glucose. Do not stop a prescribed medicine to take a supplement.
What it interacts with
Additive with glucose-lowering medication, and often taken alongside metformin in the polycystic ovary syndrome literature specifically because both act on insulin sensitivity.1
Caution
Who should not take it
Inositol raises ovulation rates in women with polycystic ovary syndrome. If you are taking it for metabolic reasons and not trying to conceive, that is a side effect worth knowing about rather than discovering.1
Caution
Discuss with your clinician before taking it in pregnancy. Trials exist in that setting, but dose and indication are decisions for someone who knows your history.
Caution
Our verdict
Reasonable to discuss with a clinician if you have polycystic ovary syndrome. Outside that, you would be extrapolating from a population you are not in.
What we can say and sell where you are
Supplement claims are permitted here with substantiation, and we carry commercial links. We still describe the evidence rather than promise a result.
No commercial links are shown in your region.
How to read the evidence labels
Every claim on this page carries a label saying how much weight it can hold. The label describes the strength of the finding, not the prestige of the journal it appeared in.
- Strong evidenceA large randomised trial, a long cohort study, or agreement between several of them.
- Emerging evidenceReal, but thin — small, short, observational, or not yet replicated.
- ContestedCompetent researchers actively disagree. We are not picking a side for you.
What the evidence covers
An umbrella review — a review of meta-analyses rather than of trials — assessed 28 pooled analyses of nutritional interventions in polycystic ovary syndrome and graded how much certainty each finding carried. Inositol came out with moderate certainty for improving fasting insulin, alongside a small number of other supplements.
The same review recorded moderate-certainty evidence that inositol increases ovulation rates in subfertile women with the condition. That is the most clinically concrete finding on this whole page, and it has nothing to do with glucose sensors.
What the evidence says
In women with polycystic ovary syndrome, inositol supplementation improved fasting insulin with moderate certainty in an umbrella review of meta-analyses.1
Emerging evidence
The same review found moderate-certainty evidence that inositol increases ovulation rates in subfertile women with polycystic ovary syndrome.1
Emerging evidence
That review found no high-certainty evidence that dietary interventions alone improved health or reproductive outcomes in polycystic ovary syndrome.1
Emerging evidence
Why the population matters more than usual here
Polycystic ovary syndrome is strongly associated with insulin resistance, which is why an insulin-sensitising supplement was tested there in the first place. But a finding in a group selected for a specific endocrine disorder does not transfer to a general reader whose only concern is a borderline HbA1c.
Every other supplement on this page is at least tested in populations resembling our readers. This one is not, and the honest framing is that it is well studied in a place most people reading this do not stand.
Common questions
- Should I take inositol for prediabetes?
- The evidence base is in polycystic ovary syndrome, not prediabetes. Applying it to yourself means assuming a finding transfers between quite different populations, which is exactly the reasoning this site tries to avoid.
- What is the difference between myo-inositol and D-chiro-inositol?
- They are different isomers, often sold together in a fixed ratio on the basis that this reflects physiological proportions. Trial evidence is mostly on myo-inositol, and the case for particular ratios is commercial more than it is established.
References
- 1.Moslehi N, Zeraattalab-Motlagh S, Rahimi Sakak F, Shab-Bidar S, Ramezani Tehrani F, Mirmiran P (2023). Effects of nutrition on metabolic and endocrine outcomes in women with polycystic ovary syndrome: an umbrella review of meta-analyses of randomized controlled trials. Nutrition Reviews. 10.1093/nutrit/nuac075
These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.