Foods and Blood Sugar: Fiber, Vinegar, Cinnamon and Others Checked
What reviews of trials found for low glycemic eating, beans, nuts, resistant starch, vinegar and cinnamon on blood sugar, and why diabetes medicines call for care with diet changes.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read functional food safety before you use anything on this page.
Read this first. If you take insulin or some other diabetes medicines, ask your diabetes team before changing how you eat. The US National Institute of Diabetes and Digestive and Kidney Diseases says low blood glucose can be a side effect of insulin or some other medicines that help the pancreas release insulin, and that severe low blood glucose is dangerous and needs treatment right away. [1] The UK National Health Service says low blood sugar usually affects people with diabetes who take insulin or some other diabetes medicines, and is rare in people without diabetes. [2] In an emergency, call 911. Never stop or change a prescribed medicine because of a food: ask the prescriber or pharmacist.
The best-supported finding is for whole eating patterns built on low glycemic index and glycemic load foods, which lowered HbA1c (a longer-term blood sugar marker) a little in people with diabetes. [3] Beans and other pulses, some nuts and some starches that resist digestion also show small effects. Vinegar and cinnamon have weaker, more mixed evidence. All of these studies measured blood markers, not complications. This page is information only and gives no meal plan.
What the research found
| Food or pattern | What the source found | Evidence label | Population and form studied |
|---|---|---|---|
| Low glycemic index or load diets | HbA1c down 0.31% versus higher-glycemic diets; certainty rated high for HbA1c [3] | Established (small change) | 29 trial comparisons, 1,617 people with type 1 and type 2 diabetes [3] |
| Pulses (beans, lentils, chickpeas, peas) | Pulses alone lowered fasting glucose; in low-glycemic diets they lowered a longer-term marker; heterogeneity was high [4] | Promising but limited | 41 trials in people with and without diabetes [4] |
| Chickpeas | Lower short-term glucose response than potatoes and wheat [5] | Promising but limited | 12 studies, 182 healthy adults, so not a diabetes result [5] |
| Pistachios | Fasting glucose down 5.32 mg/dL when swapped for other foods; no change in an insulin resistance score [6] | Promising but limited | 8 trials in people at high cardiovascular risk [6] |
| Resistant starch types 1 and 2 | Lower after-meal blood glucose [7] | Promising but limited | 31 trials in type 2 diabetes or prediabetes; type 1 is starch protected by intact plant cell walls, type 2 is high-amylose starch [7] |
| Vinegar | Better fasting glucose and HbA1c; studies were small and vinegar content varied [8] | Promising but limited | 6 studies, 317 people with type 2 diabetes [8] |
| Cinnamon | A 2013 review of 10 trials found lower fasting glucose but no significant HbA1c change, with very high heterogeneity [9]; a 2024 review of 24 trials of cinnamon supplementation reported lower fasting blood sugar [10] | Mixed | Doses from 120 mg to 6 g a day in the 2013 review; the 2024 review is about supplements [9] |
More on single foods: legumes, pistachios, resistant starch foods and whole grains.
Vinegar and cinnamon: limits
The vinegar review's authors said the studies were small and the vinegar differed, so results should be applied to a larger population with caution. [8] For side effects and medicine cautions, see apple cider vinegar and blood sugar.
The US National Center for Complementary and Integrative Health (NCCIH) says cinnamon studies are hard to interpret because it is often unclear which species or plant part was tested, and that it is unclear whether cinnamon supplementation helps diabetes. [11] NCCIH also says cassia cinnamon does not usually supply enough coumarin in food to cause significant problems, but some cassia products contain high levels, and prolonged use could be an issue for sensitive people such as those with liver disease. [11] NCCIH adds that people who take diabetes drugs should tell their health care providers about herbal supplements. [12] Cinnamon as a spice is covered in cinnamon as a food.
Frequently asked questions
Which foods are best for blood sugar?
No review we read ranks foods. Low glycemic index or load eating patterns lowered HbA1c by 0.31% in people with diabetes, and pulses showed small benefits with varied results. [3][4]
Does vinegar lower blood sugar?
A review of 6 small studies in type 2 diabetes found better fasting glucose and HbA1c, but the vinegar differed and the authors urged caution. [8]
Does cinnamon help diabetes?
Results are mixed. One review found lower fasting glucose but no significant HbA1c change, and NCCIH says it is unclear whether cinnamon supplementation helps. [9][11]
Can diet changes cause low blood sugar?
Low blood glucose is described as a side effect of insulin and some other diabetes medicines. Ask your diabetes team how food changes fit with your medicines. [1]
Are beans good if I have diabetes?
Pulses lowered fasting glucose and a longer-term marker in a review of 41 trials in people with and without diabetes, though results varied widely. [4]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
What we did not find
- Proper evidence not found in the reviews we read that any single food prevents or reverses diabetes. The outcomes in these reviews were blood markers such as HbA1c and fasting glucose.
- No review we read compared these foods against each other.
- A result in healthy adults (chickpeas) does not transfer to people with diabetes. [5]
Who should ask a clinician
People with diabetes, especially those using insulin or medicines that raise insulin, people with prediabetes planning big diet changes, pregnant people, and anyone with liver or kidney disease should talk with a clinician first. A wider picture is in prediabetes, type 2 diabetes and metabolic syndrome. For how interactions are rated, see medication interactions.
References
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Low Blood Glucose (Hypoglycemia). Read 2026-10-22.
- NHS (UK). Low blood sugar (hypoglycaemia). Read 2026-10-22.
- Chiavaroli L et al. Effect of low glycaemic index or load dietary patterns on glycaemic control and cardiometabolic risk factors in diabetes: systematic review and meta-analysis of randomised controlled trials. BMJ 2021. Read 2026-10-22.
- Sievenpiper JL et al. Effect of non-oil-seed pulses on glycaemic control: a systematic review and meta-analysis of randomised controlled experimental trials in people with and without diabetes. Diabetologia 2009. Read 2026-10-22.
- Nam T et al. Effectiveness of Chickpeas on Blood Sugar: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients 2023. Read 2026-10-22.
- Hadi A et al. Effects of pistachios on glycaemic control: a systematic review and meta-analysis of randomised controlled trials. Br J Nutr 2023. Read 2026-10-22.
- Pugh JE et al. A comparison of the effects of resistant starch types on glycemic response in individuals with type 2 diabetes or prediabetes: a systematic review and meta-analysis. Front Nutr 2023. Read 2026-10-22.
- Cheng LJ et al. A systematic review and meta-analysis: Vinegar consumption on glycaemic control in adults with type 2 diabetes mellitus. J Adv Nurs 2020. Read 2026-10-22.
- Allen RW et al. Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Ann Fam Med 2013. Read 2026-10-22.
- Moridpour AH et al. The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes mellitus: an updated systematic review and dose-response meta-analysis of randomized controlled trials. Phytother Res 2024. Read 2026-10-22.
- National Center for Complementary and Integrative Health (NCCIH). Cinnamon. Read 2026-10-22.
- National Center for Complementary and Integrative Health (NCCIH). Diabetes and Dietary Supplements. Read 2026-10-22.