Is Garlic Good for Diabetes? Benefits + Side Effects

Garlic lovers rejoice! There is one more reason to love this aromatic herb: current literature suggests both fresh garlic and garlic supplements can lower blood sugar when eaten consistently. Learn how much to eat to harness these benefits.

cloves of raw garlic on a wood table
Julia Zakrzewski, RD
— Signos
Health & Nutrition Writer
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Updated by

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Science-based and reviewed

July 19, 2024
July 17, 2022
— Updated:
March 26, 2024

Table of Contents

There is evidence that Hippocrates himself, the famous doctor from ancient Greece, prescribed garlic to treat various health conditions.1

Today, garlic continues to be popular in health circles because of its potent antioxidants and immune function support, not to mention the yummy flavor it adds to meals! The next frontier for this ancient herb? Investigating the potential link between garlic and its ability to reduce hyperglycemia and the risk of type 2 diabetes.


What Are the Effects of Garlic on Blood Sugar?

The general consensus on this question is yes, regular intake of garlic can help lower blood sugar and support healthy blood glucose levels.

A 2015 review of clinical trials gathered the strongest data available on the consumption of garlic and its effects on blood sugar control.2 Researchers compared the findings from all the studies and concluded that garlic helps to lower fasting blood sugar, but the exact mechanism of how it works is still unknown.

A study conducted in 2018 had participants eating raw crushed garlic twice a day with their standard meals over a four-week period.3 The addition of fresh garlic cloves had a beneficial effect on the symptoms associated with metabolic syndrome, including:

The conclusions of the study support the recommendation that garlic should be added to a diet to support better blood glucose control and reduce the risk of insulin resistance and cardiovascular complications like atherosclerosis.

Nutrition Facts of Garlic

Garlic may be small, but it’s a nutrition powerhouse containing many phytonutrients and active compounds that can support your health.4 The following are the basic nutrition facts for three cloves of garlic according to the USDA:5

  • Calories: 13.4 kcal
  • Carbohydrates: 3.0 grams
  • Dietary Fiber: 0.2 grams
  • Total Fat: 0 grams
  • Protein: 1.0 grams
  • Vitamin C: 2.8 milligrams
  • Selenium:1.3 micrograms
  • Phosphorus: 13.8 milligrams
  • Iron: 0.2 milligrams

Other Health Benefits of Garlic

woman riding a peloton bike indoors with windows in the background

The most potent health-promoting ingredient in garlic is allicin.6 To activate allicin, you need to crush the garlic bulb and expose it to air to activate enzymes.7 Cooking or pickling garlic will reduce some bioavailability of allicin (how much your body can absorb), but it will still be present.

Research has linked garlic to an impressive range of health benefits, from reducing the risk of getting a cold to protecting against heavy metal toxicity. Some of the most significant benefits in terms of metabolic health include:

Inhibiting Tumor Growth

Allicin has been linked to shrinking tumors, specifically in people with colon cancer.8,9 Further studies are needed to determine any potential adverse effects of herb-drug interactions for patients undergoing cancer treatment.

Antibacterial Agent

Allicin also contributes to garlic’s antibacterial properties and is often used to protect against harmful pathogenic microbes.10 Allicin has sulfur amino acid groups, so it can deactivate proteins in thiol groups (organic compounds that have a sulfur atom instead of an oxygen atom), which compromises the bacterial membrane.11

Improving Cardiovascular Health

Garlic is widely recommended to prevent and treat various cardiovascular diseases. It has also been linked to:

  • Lowering high blood pressure
  • Lowering LDL cholesterol levels
  • Reducing harmful plaque buildup in the arteries

The Mediterranean diet boasts many health benefits and relies heavily on garlic and several other ingredients. Many Mediterranean dishes include garlic with other herbs and spices potent in antioxidants and vitamins. Alone, these ingredients are healthful, but a theory within the Mediterranean diet is that the ingredients have a synergistic effect when they are cooked together.12

Following a Mediterranean diet has been shown to decrease inflammation, promote weight loss, and support excellent health.13 Popular Mediterranean dishes often include garlic, onion, tomato, olive oil, and green herbs such as parsley and oregano.

Potential Negative Side Effects and Interactions

While garlic offers many health benefits, it's crucial to understand its potential negative side effects and interactions, especially for individuals with specific health conditions or taking certain medications. Although garlic is generally safe, side effects and interactions may include:

  • Triggering or worsening heartburn
  • Increasing symptoms of IBS (irritable bowel syndrome) like bloating, gas, or nausea14
  • Causing bad breath or body odor
  • Interfering with blood-thinning medications, such as warfarin, when taken in high amounts (primarily supplements, although aged garlic supplements appear to be safer)15

If you are taking any prescription medication or have an upcoming or recent surgery, consult with your healthcare provider before starting a garlic supplement.

<p class="pro-tip"><strong>Read about </strong><a href="/blog/lower-blood-sugar-fast">How To Lower Blood Sugar Fast: 11 Natural Ways</a></p>

How to Include More Garlic in Your Diet

The biggest barrier to regular garlic intake is the dreaded bad breath after eating it! Some people are extra sensitive and will even notice a garlic smell seeping from their pores hours after consuming large amounts of fresh garlic.

A trick to reduce the strong taste of raw garlic is to chop or mince it and set it aside for ten minutes. After oxygen has reacted with the garlic, the intensity should subside, resulting in a mellower flavor. Now, you can add fresh garlic to salads or your favorite dressings!

Vegan Salad Dressing With Fresh Garlic


  • ⅓ cup olive oil
  • ⅓ cup red wine vinegar or lemon juice
  • 1 tsp honey
  • 1 tbsp grainy Dijon mustard
  • 1 garlic clove, crushed and minced
  • ½ tsp each: dried basil, dried oregano, dried parsley

Mix all ingredients and refrigerate in an airtight container for up to one week.

Cooked garlic is less pungent and easier to incorporate into meals. You can cook garlic into your stovetop recipes, like soups or roast a bulb of garlic and add it to your meals afterward.

Roasted Garlic

  • Preheat oven to 400°F.
  • Slice the entire garlic bulb in half (across the cloves) and drizzle with one teaspoon of olive oil.
  • Loosely wrap garlic in aluminum foil and place in oven to bake.
  • Check after thirty minutes. It is ready to eat when the cloves have browned.
  • Allow the bulb to cool completely before gently squeezing the cloves out. You can store roasted garlic in the refrigerator for up to a week.

Slow-roasting caramelizes the cloves and reduces the harsh taste. Roasted garlic is slightly sweet and can be used in a variety of foods, such as salads, sandwiches, stir-fries, potatoes, spreads, and more.

If the smell of fresh garlic is too much for you, consider opting for a supplement. Choose a brand with the highest concentration to ensure you still get all the health benefits.

Garlic salt and garlic powder are ineffective replacements if you want to reap the blood sugar and health benefits of garlic. Although garlic salt and powder contain trace amounts of garlic, it is not enough to impact your overall health.

Raw Garlic

The easiest way to include more garlic in your diet is to add it to everything! You can chop it up and mix it with olive oil, salt, and pepper to create a flavorful dip for vegetables or spread it on bread.

Other ways to include raw garlic in your diet include:

  • Mixing minced garlic into salad dressings and marinades.
  • Sautéing chopped garlic in olive oil and adding it to pasta, rice, and vegetables.
  • Adding crushed garlic to homemade hummus for more flavor.
  • Mixing raw garlic into mashed avocado for a healthy and delicious spread.
  • Combining diced tomatoes, minced garlic, chopped basil, and olive oil on toasted bread slices to create a simple bruschetta topping.

Garlic Tea

It doesn't sound like the most appealing beverage, but garlic tea has a long history of being used as a natural remedy to support the immune system. Garlic tea has been used traditionally to help with congestion, sore throat, and cough. To make garlic tea, simply steep 2 to 3 crushed cloves of garlic in hot water for about 5 minutes. You can add lemon juice or honey for taste and even more health benefits.

Are Garlic Supplements Worth It?

roasted garlic in a cast iron skillet

Compelling data suggests that supplementing with garlic could support various health outcomes, including helping with high blood sugar. One study found that taking a garlic supplement can reduce fasting blood sugar within 1-2 weeks.16 That’s an amazing turnaround time! 

Another study found that participants with Non-alcoholic fatty liver disease (NAFLD)─now called metabolic dysfunction-associated steatotic liver disease (MASLD)─who took garlic powder supplements had significantly lower fasting blood sugar and measures of insulin resistance.17 Insulin resistance means the pancreas is secreting more and more insulin to reduce blood sugar, but the cells aren’t responding as they should.

Garlic supplements have also been shown to lower blood pressure and support better cardiovascular health outcomes.18

If you choose to take a garlic supplement, make sure you select your garlic supplement from a reputable brand with third-party testing for purity and potency. Some formulas completely strip away the sulfur compounds that we know contain medicinal properties to make the product smell better, but won’t do much for your health. 

Always consult your doctor before taking garlic supplements to ensure they are safe for you.

How Can I Tell if Garlic Is Improving My Blood Sugar Levels?

The easiest and fastest way to tell if a change in your diet is improving your blood sugar is to look at the data! A CGM device takes a blood glucose reading every five minutes and gives you an accurate picture of how your glucose levels are changing throughout the day.

Studies suggest that moderate amounts of garlic can lower your blood sugar after one week, but for some people, it could be longer. There is also some evidence that eating garlic more frequently can help.

Try to make a point of adding garlic to at least two of your meals per day and see what your fasting glucose numbers are after one week. To increase your chances of seeing significant improvement, try to include low glycemic index foods as often as possible. Low-GI carbohydrates are filling and should have little impact on your blood sugar.

If you prefer, you can buy garlic supplements (most of them are very affordable) and follow a similar regimen. After two weeks, you should see some improvements, even if they are minor.

Key Takeaways

Both fresh garlic and garlic supplements can help support your overall health and healthy blood sugar levels. Garlic may help increase insulin sensitivity and promote metabolic health. 

To enhance the benefits of fresh garlic and dial back the sharp taste, crush or mince some garlic and let it rest exposed to air for ten minutes.

If you hate the taste of garlic, a supplement may be a good option. Try to find one with aged garlic extract in the formula, as aged garlic tends to offer the best results based on bloodwork.

Garlic supplements should not be consumed if you regularly take blood-thinning medication or have surgery. Always talk to your doctor before starting a new supplement.

<p class="pro-tip"><strong>Learn more about </strong><a href="/blog/cgm-data-weight-loss">Using CGM Data to Crack the Weight Loss Code</a></p>

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Topics discussed in this article:


  1. Rivlin, R. S. (2001). Historical Perspective on the Use of Garlic. The Journal of Nutrition, 131(3), 951S-954S.
  2. Hou, L., Liu, Y., & Zhang, Y. (2015). Garlic intake lowers fasting blood glucose: meta-analysis of randomized controlled trials. Asia Pacific Journal of Clinical Nutrition, 24(4), 575–582.
  3. Choudhary, P. R., Jani, R. D., & Sharma, M. S. (2017). Effect of Raw Crushed Garlic (Allium sativumL.) on Components of Metabolic Syndrome. Journal of Dietary Supplements, 15(4), 499–506.
  4. Shang, A., Cao, S. Y., Xu, X. Y., Gan, R. Y., Tang, G. Y., Corke, H., Mavumengwana, V., & Li, H. B. (2019). Bioactive Compounds and Biological Functions of Garlic (Allium sativum L.). Foods (Basel, Switzerland), 8(7), 246.
  5. USDA FoodData Central. (n.d.). Retrieved from
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  7. Lawson, L. D., & Hunsaker, S. M. (2018). Allicin Bioavailability and Bioequivalence from Garlic Supplements and Garlic Foods. Nutrients, 10(7), 812.
  8. Oommen, S., Anto, R. J., Srinivas, G., & Karunagaran, D. (2004). Allicin (from garlic) induces caspase-mediated apoptosis in cancer cells. European journal of pharmacology, 485(1-3), 97–103.
  9. Sarvizadeh, M., Hasanpour, O., Naderi Ghale-Noie, Z., Mollazadeh, S., Rezaei, M., Pourghadamyari, H., Masoud Khooy, M., Aschner, M., Khan, H., Rezaei, N., Shojaie, L., & Mirzaei, H. (2021). Allicin and Digestive System Cancers: From Chemical Structure to Its Therapeutic Opportunities. Frontiers in oncology, 11, 650256.
  10. Ankri, S., & Mirelman, D. (1999). Antimicrobial properties of allicin from garlic. Microbes and infection, 1(2), 125–129.
  11. Bhatwalkar, S.B., Mondal, R., Krishna, S.B.N., Adam, J.K., Govender, P., & Anupam, R. (2021) Antibacterial Properties of Organosulfur Compounds of Garlic (Allium sativum). Frontiers in Microbiology, 12:613088.
  12. Dennett, MPH, RDN, CD, C. (2016, May). Key Ingredients of the Mediterranean Diet — The Nutritious Sum of Delicious Parts - Today’s Dietitian Magazine. Key Ingredients of the Mediterranean Diet — The Nutritious Sum of Delicious Parts. Retrieved July 2022, from
  13. Tsigalou, C., Konstantinidis, T., Paraschaki, A., Stavropoulou, E., Voidarou, C., & Bezirtzoglou, E. (2020). Mediterranean Diet as a Tool to Combat Inflammation and Chronic Diseases. An Overview. Biomedicines, 8(7), 201.
  14. Bardisi, B. M., Halawani, A. K. H., Halawani, H. K. H., Alharbi, A. H., Turkostany, N. S., Alrehaili, T. S., Radin, A. A., & Alkhuzea, N. M. (2018). Efficiency of diet change in irritable bowel syndrome. Journal of family medicine and primary care, 7(5), 946–951.
  15. Ried, K., Travica, N., & Sali, A. (2016). The effect of aged garlic extract on blood pressure and other cardiovascular risk factors in uncontrolled hypertensives: the AGE at Heart trial. Integrated blood pressure control, 9, 9–21.
  16. Wang, J., Zhang, X., Lan, H., & Wang, W. (2017). Effect of garlic supplement in the management of type 2 diabetes mellitus (T2DM): a meta-analysis of randomized controlled trials. Food & Nutrition Research, 61(1), 1377571.
  17. Sangouni, A. A., Mohammad Hosseini Azar, M. R., & Alizadeh, M. (2020). Effects of garlic powder supplementation on insulin resistance, oxidative stress, and body composition in patients with non-alcoholic fatty liver disease: A randomized controlled clinical trial. Complementary therapies in medicine, 51, 102428.
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About the author

Julia Zakrzewski is a Registered Dietitian and nutrition writer. She has a background in primary care, clinical nutrition, and nutrition education. She has been practicing dietetics for four years.

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