Supplements, reviewed against the evidence

Six supplements sold for blood sugar, each reviewed the same way: what the pooled trials actually found, how good that evidence is, and who should not take it. One of the six we recommend against outright.

Safety comes before commerce on every page here, structurally — interactions and contraindications appear above any link, never below or folded away. The readers most likely to arrive on these pages are already taking medication.

What we can say and sell where you are

We carry commercial links here, but health claims for these products are not authorised, so this page describes what studies measured and makes no claim about what a product will do for you.

Supplements

  1. Berberine

    The supplement with the largest measured glucose effect on this page, and the largest interaction risk. Both halves matter.

    Strength of evidence: Some support

    Updated 2026-08-07
  2. Magnesium

    Cheap, well tolerated, and genuinely deficient in a lot of people. The glucose case is weaker than the popular one, and slower.

    Strength of evidence: Weak

    Updated 2026-08-07
  3. Chromium

    Twenty-five years of trials that keep disagreeing with each other. The disagreement is the finding.

    Strength of evidence: Weak

    Updated 2026-08-07
  4. Cinnamon

    The most-recommended glucose supplement on the internet, and the one with the clearest negative verdict from a systematic review.

    Strength of evidence: Not supported

    Updated 2026-08-07
  5. Inositol

    The one supplement here with a specific population behind it rather than a general glucose claim — and outside that population, very little.

    Strength of evidence: Weak

    Updated 2026-08-07
  6. Apple cider vinegar

    The one supplement here whose effect you can genuinely watch on a sensor — which is not the same as it improving your health.

    Strength of evidence: Weak

    Updated 2026-08-07
Why glucose matters