Apple cider vinegar for blood sugar: what the trials found.
The catch? All diabetic patients
Apple cider vinegar is sold with the promise of lower blood sugar. Here is what the controlled trials actually found, and who they actually apply to.
- Claim
- APPLE CIDER VINEGAR: WORKS?
- Catch
- SMALL TRIALS
- Verdict
- MAYBE, IF YOU HAVE DIABETES
The evidence: a 2025 GRADE-assessed systematic review and dose-response meta-analysis in Frontiers in Nutrition pooled seven controlled trials of apple cider vinegar (ACV) in people with type 2 diabetes. Against placebo, ACV reduced fasting blood sugar by −21.929 mg/dL (95% CI −29.19 to −14.67; p below 0.001) and HbA1c by −1.53 (95% CI −2.65 to −0.41; p = 0.008), while increasing fasting insulin (+2.059 µU/ml, 95% CI 0.26 to 3.86). It had no effect on HOMA-IR, the model's measure of insulin resistance. Every 1 mL/day more ACV was associated with a 1.255 mg/dL lower fasting blood sugar, and the effect was larger above 10 mL/day. A separate 2020 meta-analysis in the Journal of Advanced Nursing (6 studies, 317 patients) found better fasting glucose and HbA1c, but explicitly cautioned that "the sample sizes in the included studies were relatively small" and that "caution should be exercised when trying to extrapolate the results to a larger population." A 2021 meta-analysis (9 studies) found fasting glucose −7.97 mg/dL (I² = 75%) and HbA1c −0.50 (I² = 91%) — and noted that in apparently healthy participants, ACV intake "appeared to elicit an increase in FPG and HDL-C concentrations."
The catch, part one — this is a diabetes finding, not a health finding. Every included trial enrolled people with type 2 diabetes. The reviews' own subgroup data point the same way: in healthy people, vinegar did nothing (and may have nudged glucose the wrong way). The dose also matters: effects appeared above roughly 10 mL a day, and a body-composition meta-analysis (10 RCTs, 789 participants) found the benefit was concentrated in people who are overweight or diabetic, taking it for 12 weeks or less, at around 30 mL/day.
The catch, part two — it is an acid, and it has costs. A 12-week safety trial in type 2 diabetics found 50–56% of people drinking vinegar or pickle juice reported at least one treatment-emergent adverse event, against 11% on the vinegar-pill reference arm, and significantly lowered urinary pH. Vinegar is acidic enough to erode tooth enamel, which is the reason dietitians advise drinking it with food and rinsing with water afterwards.
Bottom line: the glucose effect in type 2 diabetes looks real and modest. It is not evidence that drinking apple cider vinegar helps healthy people, it has never been tested as a diabetes treatment in a way that would change prescribing, and it costs you enamel. If you have type 2 diabetes, this is a conversation for your doctor, not a replacement for treatment.
SOURCES
- Arjmandfard D, et al. "Effects of apple cider vinegar on glycemic control and insulin sensitivity in patients with type 2 diabetes: A GRADE-assessed systematic review and dose-response meta-analysis of controlled clinical trials." Front Nutr. 2025;12:1528383. DOI: 10.3389/fnut.2025.1528383. PMID 39949546. PMCID PMC11821484. PROSPERO CRD42023457493.
- Cheng L, et al. "A systematic review and meta-analysis: Vinegar consumption on glycaemic control in adults with type 2 diabetes mellitus." J Adv Nurs. 2020;76(6):1152–1164. DOI: 10.1111/jan.14255. PMID 31667860.
- Hadi A, et al. "The effect of apple cider vinegar on lipid profiles and glycemic parameters: a systematic review and meta-analysis of randomized clinical trials." BMC Complement Med Ther. 2021;21:364. DOI: 10.1186/s12906-021-03351-w. PMID 34187442. PMCID PMC8243436.
- Castagna A, et al. "Effect of Apple Cider Vinegar Intake on Body Composition in Humans with Type 2 Diabetes and/or Overweight: A Systematic Review and Meta-Analysis of Randomized Controlled Trials." Nutrients. 2025;17(18):3000. DOI: 10.3390/nu17183000. PMID 41010525.
- "A preliminary evaluation of the safety and tolerance of medicinally ingested vinegar in individuals with type 2 diabetes." J Med Food. 2008;11(3):571–576. DOI: 10.1089/jmf.2007.574. PMID 18361754.
Disclaimer: For information only, not medical advice. Do not start or stop diabetes treatment, and do not use vinegar as a substitute for prescribed medication. Vinegar can damage tooth enamel and may interact with some medicines — talk to your doctor or a registered dietitian before adding it to your diet.
