Apple cider vinegar helps with blood sugar

In adults with type 2 diabetes, trials that added vinegar, mostly apple cider vinegar, to the daily diet for 4 to 12 weeks found lower fasting blood sugar and lower HbA1c, a measure of average blood sugar over the previous two to three months. The trials were small, most were not blinded, and the size of the effect varied widely: the three reviews cited here that reported HbA1c for people with diabetes alone put the fall anywhere from 0.39 to 1.53 percentage points, and the authors of the review reporting 1.53 rated their own confidence in that figure as low, while two reviews that pooled adults with and without diabetes found falls of 0.50 and 0.91 points. In shorter tests, vinegar taken with a starchy meal lowered the rise in blood sugar afterwards in several small studies, but not after every kind of meal and not in every form, and in a placebo-controlled test in 36 healthy adults the rise over two hours was not clearly lower.

No trial identified in these sources tested apple cider vinegar as a replacement for diabetes medicine; in the trials one review pooled, participants were also being treated with diet, diabetes tablets or insulin. These sources do not show how often blood sugar went too low when vinegar was added to those treatments: none of the reviews that could be read in full counts episodes of low blood sugar, one of them reported safety only as laboratory tests such as liver enzymes, and the two largest reviews could be read only in summary. In people with type 1 diabetes whose stomachs already empty slowly, a condition called gastroparesis, two weeks of daily apple cider vinegar slowed stomach emptying further, and the study's authors note that slower emptying can leave mealtime insulin working before the food arrives, which can cause low blood sugar after meals; one of the ten participants reported low blood sugar more often while drinking the vinegar, and the study did not record how often it happened. In people without diabetes the picture is different: in a review of 16 randomized trials of vinegar and similar foods, fasting blood sugar did not change in healthy adults (two trials), adults with overweight or obesity (four trials) or adults with other metabolic conditions (two trials), and another review found fasting blood sugar appeared to rise rather than fall in healthy participants. Apple cider vinegar is also sold as tablets, capsules and gummies, and pill forms were tested twice in these sources, with different results: whole vinegar tablets did not lower blood sugar after a meal in healthy adults, while capsules taken daily for 12 weeks lowered fasting blood sugar in women with polycystic ovary syndrome who were all starting metformin at the same time. No trial in these sources tested gummies.

The most recent review (Arjmandfard 2025) pooled seven trials in 463 adults with type 2 diabetes in Iran, Tunisia and Pakistan, who took 13.75 to 30 mL of apple cider vinegar a day for 4 to 12 weeks. Fasting blood sugar fell by about 22 mg/dL more than in the comparison groups, and HbA1c by 1.53 points. The authors rated five of the seven trials as low quality and graded the certainty of the evidence as moderate for fasting blood sugar and low for HbA1c, and one of the seven trials is not described as randomized. The largest review (Tehrani 2025) pooled 25 trials of apple cider vinegar in 1,320 adults. Fasting blood sugar was about 21 mg/dL lower with vinegar and HbA1c 0.91 points lower, results differed very widely from one trial to the next, and a separate analysis of the participants with diabetes found falls in both. A review restricted to randomized trials (Valdes 2021) pooled 16 trials in 910 adults of vinegars of several kinds and other foods rich in acetic acid, including kimchi. In type 2 diabetes, fasting blood sugar was about 36 mg/dL lower and HbA1c 1.47 points lower, each from five trials whose results varied widely. In healthy adults, adults with overweight or obesity and adults with other metabolic conditions, each analysed from two to four trials, fasting blood sugar did not change. That review first reported no effect on HbA1c; its authors published a correction the same year, after a data entry error in the review was identified and one of the trials they had pooled turned out to have published incorrect figures.

An earlier review (Hadi 2021) pooled nine trials of apple cider vinegar in adults with diabetes, obesity or neither. Fasting blood sugar fell by about 8 mg/dL and HbA1c by 0.50 points, with results varying widely between trials, and in participants without diabetes fasting blood sugar appeared to rise. A 2018 review of 11 vinegar studies in 278 people with diabetes (Siddiqui) found HbA1c 0.39 points lower after 8 to 12 weeks. After a meal, blood sugar in that review was significantly lower only at the 30-minute reading; the 60, 90 and 120-minute readings were lower but within the range of chance. The safety measures that review reported were laboratory tests such as liver enzymes, which were no higher with vinegar; it does not report how often blood sugar went too low.

The effect after a meal depended on the meal. In 16 adults with type 2 diabetes, vinegar added to mashed potatoes and milk cut the rise in blood sugar over two hours by about 40 percent, while added to wholegrain bread, lettuce and cheese it made no measurable difference (Liatis 2010). In 11 adults with newly diagnosed type 2 diabetes who were not yet taking diabetes drugs, 30 mL of vinegar before a mixed meal lowered blood sugar and raised the amount of glucose taken up by forearm muscle compared with water (Mitrou 2015). In 12 healthy young adults, 25 g of liquid vinegar, a little under two tablespoons, taken before a meal cut the one-hour rise in blood sugar by 31 percent compared with water, while four commercial vinegar tablets swallowed whole, carrying slightly more acetic acid, gave the same result as water (Feise 2020). In 36 healthy adults in Türkiye randomly assigned to a peach nectar drink with or without 20 mL of apple cider vinegar, taken with toast and cheese, blood sugar was lower with vinegar at one hour (110 against 124 mg/dL) but not at 30, 45 or 120 minutes, and the rise over two hours was about 25 percent smaller, a difference within the range of chance (Süzen 2026).

Capsules were tested against a placebo in one trial (Najafi 2026). In Iran, 94 women with polycystic ovary syndrome, metabolic syndrome and insulin resistance, none of them pregnant and none with diabetes, all started metformin and took three capsules a day of either apple cider vinegar powder or corn starch for 12 weeks, with neither the women nor the researchers knowing who had which. Fasting blood sugar fell from about 108 to 100 mg/dL with the vinegar capsules and stayed at about 105 with placebo, and fasting insulin and a calculated measure of insulin resistance were also lower. The share of women whose insulin resistance fell below the trial's cutoff, 17 percent against 8.5 percent, was within the range of chance. Because every woman was also starting metformin, the trial shows what the capsules added to that drug, not what they do by themselves.

In rats given a sugary drink for five weeks, adding apple vinegar kept blood sugar close to that of rats given plain water (Ousaaid 2020). That study was in animals and does not measure the size of any effect in people. The trials ran for weeks, not years, and measured blood tests rather than diabetes complications. Most used liquid vinegar, many were run in Iran, and the trials that found lower blood sugar mostly enrolled adults who already had type 2 diabetes.