Does apple cider vinegar help with insulin resistance?

Not on the measures trials have used. Vinegar lowers blood sugar a little, and insulin resistance has not moved in any pooled analysis we found. A 2026 umbrella review of 19 randomized trials found fasting blood glucose 9.40 mg/dL lower with vinegar, on moderate certainty evidence. Across 8 trials in the same review, HOMA-IR, the usual blood test estimate of insulin resistance, did not fall at all. The trials were small, mostly from Iran, and most lasted 4 to 12 weeks, many of them in adults who were overweight or had type 2 diabetes.

Myth. The specific claim that apple cider vinegar reverses insulin resistance has been tested and the measure did not change. A 2025 meta-analysis found no change in HOMA-IR across 3 trials in 173 people with type 2 diabetes. In the one 8-week trial we read in full, HOMA-IR rose with vinegar while it fell in the control group, p = 0.04.

Unsettled. The fall in blood sugar is real in the pooled numbers, and its size is uncertain for reasons we can name. Five of the 7 apple cider vinegar trials in type 2 diabetes were rated low quality. Most had no placebo drink. The umbrella review found signs that small negative trials on HbA1c went unpublished.

What the trials found

Fasting blood sugar

The umbrella review gathered meta-analyses of vinegar of any kind and re-estimated the effect from 19 trials. Fasting glucose fell by 9.40 mg/dL, with a 95% confidence interval from 6.34 to 12.46, rated moderate certainty. The trials disagreed with each other a great deal, with heterogeneity of 96.3%, and the fall was larger in type 2 diabetes and in trials longer than 8 weeks. A 2021 meta-analysis limited to apple cider vinegar found a fall of 7.97 mg/dL across 6 studies lasting 30 to 90 days, interval 2.21 to 13.74. The umbrella review rated that meta-analysis low quality.

In people with type 2 diabetes the numbers are larger. A 2025 meta-analysis of 7 trials in 463 adults in Iran, Tunisia and Pakistan, taking apple cider vinegar with about 5% acetic acid for 4 to 12 weeks, found fasting blood sugar 21.93 mg/dL lower, interval 14.67 to 29.19, moderate certainty. Five of those 7 trials were rated low quality and four were not blinded. An older meta-analysis of 16 trials of acetic acid, the main acid in vinegar, in 910 adults found fasting glucose 35.73 mg/dL lower in type 2 diabetes, interval 7.67 to 63.79, and most of its trials were at unclear or high risk of bias.

HbA1c, the three-month average

Across 11 trials in the umbrella review, HbA1c fell by 0.70 percentage points, interval 0.33 to 1.07. Begg's test for publication bias came out at p = 0.037 and heterogeneity was 98.1%, so the size of that fall is unreliable. The 2021 apple cider vinegar meta-analysis found 0.50 points, interval 0.09 to 0.90. The 2025 analysis in type 2 diabetes found 1.53 points across 4 studies in 319 people, on low certainty evidence. The 16-trial acetic acid meta-analysis found no significant change in HbA1c.

The one trial we read in full randomized 73 adults with type 2 diabetes in Iran to 2 tbsp (30 mL) of apple cider vinegar a day with diet advice, or diet advice alone, for 8 weeks. HbA1c fell more with vinegar, p below 0.001, and fasting glucose fell significantly only in the vinegar group. There was no placebo drink, and the vinegar group also lost more weight.

Insulin resistance

This is the outcome the question asks about, and the answer is the same in every analysis. In the umbrella review HOMA-IR moved 0.13 higher across 8 trials, interval 0.37 lower to 0.64 higher, p = 0.608, with no significant subgroup. Fasting insulin did not change significantly either. The 2021 meta-analysis found no change in insulin or HOMA-IR. The 2025 analysis in type 2 diabetes found HOMA-IR 0.63 higher, interval 0.99 lower to 2.25 higher, on low certainty evidence. In the 8-week trial, HOMA-IR and insulin both went up with vinegar and down in the controls.

HOMA-IR is an estimate from one fasting blood sample. No trial we found measured insulin sensitivity with a clamp, the reference test, over weeks of vinegar.

After a meal

The clearest effect is on the rise in blood sugar after eating. Taken with a meal, vinegar lowered after-meal glucose by 14.59 mg/dL across 15 trials in the umbrella review, interval 2.06 to 27.11, moderate certainty. A 2017 meta-analysis of meal trials found both the glucose and the insulin response lower, with standardized differences of 0.60 and 1.30. These are mostly single-meal crossover tests, and they say nothing about long-term control.

The meal matters. In 16 people with type 2 diabetes, vinegar added to a high glycemic index meal cut the two-hour glucose area from 311 to 181 mmol min/l, p = 0.04, and did nothing with a low glycemic index meal. In small crossover trials of 9 to 10 people, about 2 teaspoons of vinegar lowered after-meal glucose by about 20% with a starchy meal. It had no effect with simple sugars, and neutralized acetate had none.

Who should be careful

Not for everyone. If you have diabetes with gastroparesis, vinegar may make it worse. In 10 adults with type 1 diabetes and diagnosed gastroparesis, apple cider vinegar before a rice pudding meal slowed stomach emptying further, a median of 17% against 27% with water. It was a small pilot without randomization, and the authors flagged slower emptying as a risk for glucose control. That matters most for people who time insulin to their meals.

Vinegar is an acid. Dutch dentists traced erosive tooth wear in a 15-year-old girl to a daily glass of apple cider vinegar. After a throat injury from an apple cider vinegar tablet, tests of 8 tablet brands found tablet size, acidity and label claims varied widely, and it was unclear whether some contained vinegar at all. In 16 healthy adults, the drop in appetite after drinking vinegar came with higher nausea ratings.

The 8-week trial of 2 tbsp (30 mL) a day reported no adverse effects, and it did not grade them systematically or measure potassium, tooth enamel or low blood sugar. We found no trial of vinegar alongside insulin, sulfonylureas or other diabetes medicines, so whether it adds to their effect on blood sugar is unknown. That absence is not reassurance. If you take a medicine that can push blood sugar too low, adding a daily dose of vinegar is a question for the person treating you.

What expert bodies say

The American Diabetes Association Standards of Care 2026 do not mention vinegar. Their recommendation on supplements says that micronutrients, herbs or spices are not recommended for glycemic benefit, at evidence grade C. That recommendation is about supplements in general, and the silence on vinegar is our reading of the full section. The EU health claims register holds no claim about vinegar and blood sugar, authorized or not.

How we searched

What would change this answer

• A placebo-controlled trial of six months or more that measures HbA1c and insulin sensitivity with a clamp. We found no such trial, and no registered trial on blood sugar or insulin resistance at all.
• Larger trials outside Iran with a placebo drink, so that weight loss and diet advice cannot explain the fall in blood sugar.
• Any trial in people taking insulin or sulfonylureas, to show whether vinegar adds a risk of low blood sugar.
• Long-term data on tooth enamel and blood potassium in people drinking vinegar every day.

More on this food: apple cider vinegar, apple cider vinegar and weight loss and apple cider vinegar and cholesterol.

Sources

1. ev-acvbs-01 · Meta-analysis or systematic review · umbrella review of meta-analyses of randomized controlled trials with re-estimated effects and GRADE · n = 19 trials
   vinegar intake was associated with a significant reduction in FBG levels in comparison to the control group (MD = −9.40 mg/dL; 95% CI: −12.46, −6.34; p = < 0.001; GRADE = moderate)
   
   Who: adults in 19 randomized trials of vinegar drawn from seven meta-analyses, healthy, overweight or with type 2 diabetes
   Effect: FBG MD -9.40 mg/dL (95% CI -12.46 to -6.34); GRADE moderate; I2 96.3%; larger in type 2 diabetes and with more than 8 weeks
   Certainty: Covers all vinegar types; apple cider vinegar subgroup significant. Heterogeneity very high; trials small and mostly from Iran.
   Food Science & Nutrition, 2026 (Shahmohammadi et al., umbrella review) · checked 2026-10-07 · we read the full_text
2. ev-acvbs-02 · Meta-analysis or systematic review · umbrella review of meta-analyses of randomized controlled trials with re-estimated effects and GRADE · n = 11 trials
   consuming vinegar had a significant effect on HbA1c levels, compared to a control group (MD = −0.70%; 95% CI: −1.07, −0.33; p = < 0.001; GRADE = moderate)
   
   Who: adults in 11 randomized trials of vinegar drawn from four meta-analyses
   Effect: HbA1c MD -0.70% (95% CI -1.07 to -0.33); GRADE moderate; I2 98.1%; Begg's test p = 0.037; significant in type 2 diabetes
   Certainty: Publication bias plus near-total heterogeneity make the size of the HbA1c fall unreliable.
   Food Science & Nutrition, 2026 (Shahmohammadi et al., umbrella review) · checked 2026-10-07 · we read the full_text
3. ev-acvbs-03 · Meta-analysis or systematic review · umbrella review of meta-analyses of randomized controlled trials with re-estimated effects and GRADE · n = 8 trials
   investigated HOMA‐IR with vinegar intake and reported a non‐meaningful rise (MD = 0.13; 95% CI: −0.37, 0.64; p = 0.608; GRADE = moderate)
   
   Who: adults in 8 randomized trials of vinegar from three meta-analyses
   Effect: HOMA-IR MD +0.13 (95% CI -0.37 to 0.64; p = 0.608); GRADE moderate; no subgroup significant; fasting insulin MD +0.82 uU/mL, not significant
   Certainty: This is the outcome closest to the H1 question; fasting glucose falls while measured insulin resistance does not.
   Food Science & Nutrition, 2026 (Shahmohammadi et al., umbrella review) · checked 2026-10-07 · we read the full_text
4. ev-acvbs-04 · Meta-analysis or systematic review · umbrella review of meta-analyses of randomized controlled trials with re-estimated effects and GRADE · n = 15 trials
   demonstrated that vinegar consumption significantly improved PPG levels in comparison to the control group (MD = −14.59 mg/dL; 95% CI: −27.11, −2.06; p = 0.022; GRADE = moderate)
   
   Who: adults in 15 randomized trials of vinegar with a test meal, from four meta-analyses
   Effect: postprandial glucose MD -14.59 mg/dL (95% CI -27.11 to -2.06); GRADE moderate; I2 93.6%; apple cider and wine vinegar significant
   Certainty: Mostly single-meal crossover trials; says nothing about long-term control.
   Food Science & Nutrition, 2026 (Shahmohammadi et al., umbrella review) · checked 2026-10-07 · we read the full_text
5. ev-acvbs-05 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis of controlled clinical trials with GRADE · n = 463
   ACV significantly reduced FBS based on the results of a random-effect model (WMD: −21.929 mg/dL, 95% CI: −29.19, −14.67, p < 0.001), with non-significant heterogeneity (I2 = 20.11%, p = 0.237) (Figure 2A).
   
   Who: adults with type 2 diabetes in Iran, Tunisia and Pakistan; 4 to 12 weeks of apple cider vinegar with about 5% acetic acid
   Effect: FBS WMD -21.93 mg/dL (95% CI -29.19 to -14.67); I2 20.1%; GRADE moderate; each extra 1 mL/day about -1.26 mg/dL
   Certainty: Five of seven trials low quality (high risk of bias in more than 2 domains); four unblinded.
   Frontiers in Nutrition, 2025 (GRADE-assessed dose-response meta-analysis of apple cider vinegar in type 2 diabetes) · checked 2026-10-07 · we read the full_text
6. ev-acvbs-06 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis of controlled clinical trials with GRADE · n = 173
   ACV did not influence HOMA-IR significantly (WMD: 0.631, 95% CI: −0.99, 2.25, p = 0.446)
   
   Who: adults with type 2 diabetes in 3 trials of apple cider vinegar
   Effect: HOMA-IR WMD +0.63 (95% CI -0.99 to 2.25; p = 0.446); GRADE low; HbA1c WMD -1.53 (95% CI -2.65 to -0.41), 4 studies, 319 people
   Certainty: Only 3 trials; GRADE low for HOMA-IR and HbA1c.
   Frontiers in Nutrition, 2025 (GRADE-assessed dose-response meta-analysis of apple cider vinegar in type 2 diabetes) · checked 2026-10-07 · we read the full_text
7. ev-acvbs-07 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis of controlled clinical trials with GRADE · n = 7 trials
   Five trials were classified as low quality (high bias risk in >2 domains) (24, 25, 27, 28, 30), one trial was classified as moderate quality (high bias risk in 2 domains) (29) and one was classified as high quality (high bias risk in <2 domains) (26).
   
   Who: 7 controlled trials of apple cider vinegar in type 2 diabetes, published 2009 to 2023
   Effect: 5 low, 1 moderate, 1 high quality by Cochrane risk of bias
   Certainty: Explains why the fasting glucose effect is rated moderate and HOMA-IR low certainty.
   Frontiers in Nutrition, 2025 (GRADE-assessed dose-response meta-analysis of apple cider vinegar in type 2 diabetes) · checked 2026-10-07 · we read the full_text
8. ev-acvbs-08 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized clinical trials, random effects · n = 6 studies
   Pooled effect size from 6 studies, with 7 effect sizes, revealed a significant reduction in FPG (− 7.97 mg/dL; 95% CI: − 13.74, − 2.21, P = 0.007; I2: 75%) after ACV consumption.
   
   Who: adults in clinical trials of apple cider vinegar for 30 to 90 days, mostly type 2 diabetes or overweight
   Effect: FPG WMD -7.97 mg/dL (95% CI -13.74 to -2.21; I2 75%); HbA1c -0.50 (95% CI -0.90 to -0.09); insulin and HOMA-IR not significant
   Certainty: Rated low quality on AMSTAR 2 by the 2026 umbrella review; heterogeneity high for FPG and HbA1c.
   BMC Complementary Medicine and Therapies, 2021 (Hadi et al.) · checked 2026-10-07 · we read the full_text
9. ev-acvbs-09 · Meta-analysis or systematic review · systematic review and meta-analysis of clinical trials · n = —
   The pooled analysis of studies revealed a significant mean glucose and insulin area under the curve (AUC) reduction in participants who consumed vinegar compared with the control group (standard mean difference=-0.60, 95%CI -1.08 to -0.11, p=0.01 and -1.30, 95%CI -1.98 to -0.62, p<0.001, respectively).
   
   Who: participants in controlled trials of vinegar co-ingested with a meal
   Effect: glucose AUC SMD -0.60 (95% CI -1.08 to -0.11); insulin AUC SMD -1.30 (95% CI -1.98 to -0.62)
   Certainty: Single-meal outcomes; number of trials and people not given in the abstract; full text paywalled.
   Diabetes Research and Clinical Practice, 2017 (Shishehbor, Mansoori, Shirani) · checked 2026-10-07 · we read the abstract
10. ev-acvbs-10 · Randomized controlled trial(s) · randomized controlled trial, open label, 8 weeks · n = 73
    HbA1C decreased in the ACV group more than in the control group and this difference was significant between the two groups (p < 0.001).
    
    Who: adults with type 2 diabetes in Iran; 2 tbsp (30 mL) apple cider vinegar a day, optionally in 3.4 fl oz (100 mL) water, plus diet advice, versus diet advice alone
    Effect: HbA1c fell more with vinegar than in controls (p < 0.001); fasting glucose fell significantly only in the vinegar group (p = 0.01)
    Certainty: No placebo drink; weight also fell more with vinegar.
    Frontiers in Clinical Diabetes and Healthcare, 2023 · checked 2026-10-07 · we read the full_text
11. ev-acvbs-11 · Randomized controlled trial(s) · randomized controlled trial, open label, 8 weeks · n = 73
    HOMA-IR was increased in the ACV group, but decreased in the control group and showed a significant difference (p = 0.04).
    
    Who: adults with type 2 diabetes in Iran, 8 weeks of 2 tbsp (30 mL) apple cider vinegar a day
    Effect: HOMA-IR up with vinegar, down in controls (p = 0.04); insulin up with vinegar (p < 0.001 between groups)
    Certainty: Direction opposite to the insulin-resistance claim; small open-label trial.
    Frontiers in Clinical Diabetes and Healthcare, 2023 · checked 2026-10-07 · we read the full_text
12. ev-acvbs-12 · Observational data · non-randomized crossover pilot study, fixed order (water then vinegar), investigator-blinded ultrasound · n = 10
    Gastric emptying rates after the meal including vinegar were significantly lower (p < 0.05) than after the reference meal.
    
    Who: 10 adults with type 1 diabetes and diagnosed diabetic gastroparesis, mean age 67.9 years; honey-flavored commercial apple cider vinegar (5% acetic acid) before a 300 g rice pudding meal
    Effect: median gastric emptying rate 17% with vinegar versus 27% with water (p < 0.05)
    Certainty: Tiny pilot without randomization; glucose itself not analyzed in detail. Relevant to people on insulin, where slower emptying can mismatch insulin timing.
    BMC Gastroenterology, 2007 (Hlebowicz et al.) · checked 2026-10-07 · we read the full_text
13. ev-acvbs-13 · Randomized controlled trial(s) · randomized controlled trial, 8 weeks · n = 73
    We found no adverse effects after consuming ACV.
    
    Who: adults with type 2 diabetes in Iran
    Effect: no adverse effects reported over 8 weeks
    Certainty: Adverse effects not systematically graded; potassium, tooth enamel and hypoglycemia on drugs not measured.
    Frontiers in Clinical Diabetes and Healthcare, 2023 · checked 2026-10-07 · we read the full_text
14. ev-acvbs-14 · Position of an expert body · clinical practice guideline (ADA Standards of Care 2026, section 5) · n = —
    Assess intake of supplements, as supplementation with micronutrients (e.g., vitamins and minerals, such as magnesium or chromium) or herbs or spices (e.g., cinnamon and aloe vera) is not recommended for glycemic benefits.
    
    Who: adults with diabetes, recommendation 5.16 (evidence grade C)
    Effect: supplementation with micronutrients, herbs or spices not recommended for glycemia; vinegar not addressed
    Certainty: Silence on vinegar is our reading of the full section text (no occurrence of the word); the recommendation is about supplements in general.
    American Diabetes Association Professional Practice Committee, 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes-2026, Diabetes Care 2026;49(Suppl 1):S89-S131 · checked 2026-10-07 · we read the section
15. acvr8-01 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 910
    Sixteen studies were included, involving 910 participants who consumed between 750 and 3600 mg acetic acid daily in interventions lasting an average of 8 weeks. Dietary acetic acid supplementation resulted in significant reductions in TAG concentrations in overweight and obese but otherwise healthy individuals (mean difference [MD] = -20.51 mg/dL [95% confidence intervals = -32.98, -8.04], P = .001) and people with type 2 diabetes (MD = -7.37 mg/dL [-10.15, -4.59], P < .001). Additionally, acetic acid supplementation significantly reduced FBG levels (MD = -35.73 mg/dL [-63.79, -7.67], P = .01) in subjects with type 2 diabetes compared with placebo and low-dose comparators.
    
    Who: Adults in 16 RCTs, 910 participants, 750 to 3600 mg acetic acid daily for about 8 weeks
    Effect: FBG MD -35.73 mg/dL (95% CI -63.79 to -7.67) in T2D; TAG MD -20.51 mg/dL (-32.98 to -8.04) in overweight or obese
    Certainty: Most trials unclear or high risk of bias; acetic acid from various vinegars, not ACV only.
    J Acad Nutr Diet, 2021 · checked 2026-09-29 · we read the abstract
16. acvr8-02 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 910
    Five of the 16 studies did not specify the dose of acetic acid delivered, and no studies measured blood acetate concentrations. Only one study controlled for background acetic acid-rich food consumption during intervention periods. Most studies had an unclear or high risk of bias. ... No significant effects of dietary acetic acid consumption were seen on HbA1c, HDL, or anthropometric markers.
    
    Who: Adults in 16 RCTs of dietary acetic acid
    Effect: No significant change in HbA1c, HDL, BMI or body fat
    Certainty: Five trials did not state the acetic acid dose; no blood acetate measured.
    J Acad Nutr Diet, 2021 · checked 2026-09-29 · we read the abstract
17. acvr8-04 · Randomized controlled trial(s) · randomized crossover · n = 16
    In group A, the incremental area under the curve of glucose (GiAUC(120)) was lower after the addition of vinegar (181+/-78 mmol min/l vs 311+/-124 mmol min/l, P=0.04). ... In group B, the addition of vinegar did not affect either the GiAUC(120) (229+/-38 mmol min/l vs 238+/-25 mmol min/l, P=0.56) or the IiAUC(120) (2996+/-1302 microU min/ml vs 3007+/-1255 microU min/ml, P=0.98).
    
    Who: Patients with type 2 diabetes, 16 in two groups of matched meals
    Effect: Glucose iAUC 181 vs 311 mmol min/l with vs without vinegar (P=0.04); no change with low-GI meal
    Certainty: Small, single meal test.
    Eur J Clin Nutr, 2010 · checked 2026-09-29 · we read the abstract
18. acvr8-05 · Randomized controlled trial(s) · randomized crossover trials · n = 9-10 per trial
    Two teaspoons of vinegar ( 10 g) effectively reduced PPG, and this effect was most pronounced when vinegar was ingested during mealtime as compared to 5 h before the meal. Vinegar did not alter PPG when ingested with monosaccharides, suggesting that the antiglycemic action of vinegar is related to the digestion of carbohydrates. Finally, sodium acetate did not alter PPG, indicating that acetate salts lack antiglycemic properties. ... In these situations, vinegar attenuated PPG by 20% compared to placebo.
    
    Who: Adults with and without type 2 diabetes, 9 to 10 per trial, four crossover trials
    Effect: Postprandial glucose about 20% lower than placebo with complex carbohydrate meals
    Certainty: Very small samples; single meal.
    Ann Nutr Metab, 2010 · checked 2026-09-29 · we read the abstract
19. acvr8-10 · Randomized controlled trial(s) · randomized crossover · n = 16
    In Study 1, ingestion of vinegar significantly reduced quantitative and subjective measures of appetite, which were accompanied by significantly higher nausea ratings, with unpalatable treatment having the greatest effect. ... On this basis the promotion of vinegar as a natural appetite suppressant does not seem appropriate.
    
    Who: Healthy normal weight young adults, 16 in study 1 and 14 in study 2
    Effect: Lower appetite with higher nausea ratings; tasting without swallowing had no effect
    Certainty: Acute only.
    Int J Obes (Lond), 2014 · checked 2026-09-29 · we read the abstract
20. ev-acvw-06 · Laboratory or animal data · case report · n = 1
    Erosive tooth wear was diagnosed in the dentition of a 15-year-old girl with a Moroccan background. After an anamnesis, extensive analysis of possible risk factors and a study of the pattern of erosion, it was concluded that the erosive tooth wear was induced by daily consumption of a glass of apple cider vinegar
    
    Who: one 15-year-old girl
    Effect: erosive tooth wear attributed to daily apple cider vinegar
    Certainty: Single case; shows the mechanism of harm, not how often it happens.
    Nederlands Tijdschrift voor Tandheelkunde, 2012, 119(12):589-91 · checked 2026-10-06 · we read the abstract
21. ev-acvw-07 · Laboratory or animal data · case report with laboratory product analysis · n = 8 products
    Considerable variability was found between the brands in tablet size, pH, component acid content, and label claims.
    
    Who: eight apple cider vinegar tablet products tested after one reported adverse event
    Effect: considerable variability in tablet size, pH, acid content and label claims
    Certainty: One injury case; the product data date from 2005.
    Journal of the American Dietetic Association, 2005, 105(7):1141-4 · checked 2026-10-06 · we read the abstract