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Home arrow Health arrow Diabetes arrow Is Onion Good for Diabetes? Glycemic Index and Sugar Content

Is Onion Good for Diabetes? Glycemic Index and Sugar Content

Written by Edibel Quintero, RD
Fact checked by Rosmy Barrios, MD
Last update: March 31, 2023
8 min read 1514 Views 0 Comments
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Many with diabetes wonder if they should eat onions and if they even have any health benefits at all. So let’s talk about how onions impact your health!

is onion good for diabetes

Onions are a versatile root vegetable with over two dozen varieties, including red onion, green onion, and yellow onion. It is the perfect addition to your meal, whether topped on a salad, used in a casserole or cooked into a soup. 

However, it contains some natural sugars, and therefore, many individuals with diabetes mellitus worry that eating onions will promote high blood glucose. But do onions have health benefits that outweigh the downsides? Can onions really treat diabetes?

Read on to learn more about eating onions with diabetes. 

Are Onions Good for Diabetes?

Onions are good food for diabetes overall because they have a low glycemic index and are rich in antioxidants, fiber, vitamins, and minerals. Consume onions to support a healthy and balanced diet, even with diabetes.

Nutritional Value of Onions

According to the United States Department of Agriculture (USDA) food database, a 100-gram serving of raw onions, specifically red onions, contains only 40-44 calories. It has about ~10 grams of carbohydrates, including two grams of dietary fiber and five grams of sugar. 

This nutritional information is very similar for yellow or white onions as well as red onions. 

Onions have significant amounts of vitamin C, potassium, and trace amounts of other vitamins and minerals – more on the benefits of these nutrients below! 

Finally, onions have only 0.05 grams of fat per 100 grams and therefore are considered fat-free. They are full of flavor but do not add fat, salt, or cholesterol to your dish. 

Keto Friendly
Key nutritional facts (per 100g):
Net carbs
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Glycemic Index

Glycemic Index of Onions

The glycemic index is valuable for those with diabetes mellitus as it quantifies how quickly food or beverages cause blood sugar levels to rise or spike. It is best for those with diabetes to consume foods that are low to moderate in their glycemic indexes. 

Typically vegetables, such as onions or red onions, have very low glycemic indexes because they are low in sugar and high in fiber. 

More specifically, onions have a glycemic index of 15, considered very low. Therefore, onions will not quickly spike blood sugar levels. 

While sugar is what causes the blood sugar to spike and can have a high glycemic index, what causes onions specifically to have a low glycemic index is the dietary fiber content. 

Dietary fiber in foods that also have sugar helps to slow down the digestion and absorption of these sugars, preventing the blood glucose levels from spiking too quickly. Proteins and fats do this as well and help to lower the glycemic index.

This is especially true since a 100-gram serving, which is more than 2/3 of a whole onion, only contains ten grams of carbohydrates.

What Are the Benefits of Onions for Diabetes?

White, yellow, and red onions are a vegetable that is beneficial for any individual, whether or not they have a chronic disease. However, onions have some specific advantages for those with diabetes mellitus as well.

#1 Rich in antioxidants 

According to the International Journal of Vegetable Science, onions are rich in antioxidants, such as phenol. 

Antioxidants are compounds in the foods we eat that help protect the body’s cells and fight against harmful free radicals, which are naturally produced from processes such as metabolism.

It is essential to have plenty of antioxidants in the diet, especially with diabetes, as antioxidants help reduce inflammation and oxidative stress, including high blood pressure.

The anti-inflammatory properties are also thought to come from chemical sulfur compounds present in the onions. According to the journal Molecules, the sulfur compounds in onions include non-toxic sulfur and methylsulfonylmethane.

#2 High in potassium

A 100-gram serving of raw onions contains 182 milligrams of potassium. 

Potassium, an essential mineral, helps the body maintain fluid and electrolyte balance and sodium. Additionally, potassium aids in regulating high blood pressure, heart rate, and muscle contraction.

According to the University of Central Florida Health, when someone with diabetes has high blood sugar levels, potassium moves into the fluid around the cells, causing high blood potassium levels.

When insulin works to let glucose into the cells, the potassium follows, causing a drop in blood potassium levels. 

However, those with low levels of potassium release less insulin and can increase the risk of type 2 diabetes.

While research continues to emerge about the relationship between a potassium-rich diet and diabetes, it is an essential nutrient in a healthy diet for those with diabetes.

#3 Source of vitamin C, or ascorbic acid

Similarly, 100 grams of raw onion contains over eight milligrams of vitamin C, also known as ascorbic acid. 

Besides being an antioxidant, ascorbic acid is essential for those with diabetes. 

A study in the Indian Journal of Medical Research found that individuals who received supplemental amounts of ascorbic acid had lower blood lipid and blood glucose levels than those with type 2 diabetes.

Therefore, these individuals had decreased risk of complications that diabetes mellitus gradually leads to, such as metabolic disorder or atherosclerosis, which is the hardening of arteries.

Additionally, the journal Nutrients discusses how individuals with type 2 diabetes or obesity, which often co-occur, have increased needs for this vitamin.

#4 Slows down the digestion and absorption of sugars

Raw onion contains about two grams of dietary fiber per serving of 100 grams.

Fiber (along with protein and fat) slows down the digestion and absorption of sugar from the foods we eat, preventing quick spikes in blood glucose levels. 

For this reason, many fruits and vegetables have a very low glycemic index. 

#5 Helps to promote weight loss

Since there are only 44 calories in 100 grams of onion, onion is a great way to add flavor to a dish without increasing caloric or fat content. When adding onion, you get an increased nutritional profile of your meal as well since you are adding antioxidants, vitamins, minerals, and more. 

Remember that an average whole onion is about 140 grams, so you would have to consume a lot of onion to get close to 44 calories which are 100 grams. 

In other words, since onions are so low in calories, they are good for those trying to boost the flavor of their dishes through low-calorie foods. This is important to note because many with diabetes, specifically type 2 diabetes, strive to lose weight to improve their condition. 

According to the Cleveland Clinic, losing even a small amount of weight can lower blood sugar levels in those with diabetes mellitus. Therefore, onions can be a great way to help lose weight, lower blood sugar and manage complications of diabetes. 

#6 Helps reduce blood cholesterol levels

According to the American Heart Association, people with diabetes have an increased risk of having high blood cholesterol levels. 

Cholesterol is a type of fat, similar to wax, produced in the liver. Since our bodies can make it, we can survive without consuming any in the diet. However, it is also present in animal products that we eat, including poultry and fish. 

When we consume excessive amounts of cholesterol, it can build up in the arteries and bloodstream. This process creates a plaque. Eventually, if the plaque builds up so much, it can completely block the artery and therefore the blood flow, causing a heart attack or stroke.

However, studies have demonstrated that onions could potentially reduce the “bad” cholesterol levels in the blood, called low-density lipoprotein, or LDL. 

A study performed in the Journal of Obstetrics and Gynaecology Research found that the participants who consumed large amounts of raw red onions had a statically significant decrease in blood cholesterol levels compared to a control group. 

Therefore, consuming onions can be beneficial to individuals with high blood cholesterol levels, which is often those with diabetes mellitus.

However, more research needs to be done specifically on participants with diabetes and onion consumption to determine the effect on blood cholesterol levels. 

#7 Potential therapeutic approach to diabetes management

Onions contain a specific class of antioxidants called anthocyanins. A literature summary by the Current Medicinal Chemistry journal described the potential of anthocyanins in the management of diabetes progression and complications or comorbidities. 

Many individuals with diabetes experience complications such as diabetic retinopathy, neuropathy, nephropathy, and vascular disorders. Studies have shown the potential of anthocyanins to support health and manage the complications that often come with diabetes. 

Similarly, more research needs to be done to continue to demonstrate this potential benefit. 


Is onion low glycemic?

Yes, onions have a glycemic index value of 15. This glycemic value is classified as a low glycemic food that does not cause significant blood sugar fluctuations.

Are onions good for type 2 diabetes?

Yes, onions are good for type 2 diabetes because they contain vitamins and minerals. These nutrients can act as antioxidants to promote health with diabetes.

How often is it recommended to eat onion for diabetes?

Since there is no specific recommendation for onion consumption with diabetes, consume it freely as 100 grams of onion only contains ten grams of carbohydrates.

How to use onion for diabetes?

Add onion to flavor your meals without adding significant calories or fat. Use onion as a flavoring instead of adding high fat, sugar, or salt additions to your meals.

Are onion rings good for diabetes?

No, onion rings are high in saturated fat and carbs, which makes them unhealthy for diabetics.

A Word From a Nutritionist

Whether raw, sauteed, or caramelized onions, they are a nutritious and delicious vegetable. They can add a spicy or sweet flavor to your meals, from salads and omelets to onion soups and sandwiches.

Especially when paired with lean protein and healthy fat, onions can be a part of a satisfying and balanced meal that does not quickly spike your blood glucose levels.

Protein, fat, and fiber help to slow the digestion and absorption of sugars in the food you eat. This, in turn, prevents the quick rise in blood sugars and lowers the glycemic index.

Because all types of onions are so low in calories, it isn’t easy to consume enough onion to even get to 50 calories worth. However, this makes onions the ideal option for weight loss and heart health, especially when replacing salt in the diet.

There is essentially no reason to limit onions in your diet, even with diabetes, as long as you do not have any allergies or intolerances to onion or onion extract.

Overall, this is a food rich in vitamins and minerals essential to a balanced and healthy diet.


Onions are a great root vegetable to add to your diet if you have diabetes for many reasons. 

They are rich in antioxidants, such as phenol and vitamin C, that help to reduce inflammation, high blood pressure, and even blood cholesterol levels. 

Overall, antioxidants are compounds essential in reducing oxidative stress, which plays a major role in diabetes. 

All types of onions are very low in calories and fat. However, they are rich in flavor, vitamins, and minerals. 

Finally, onions have a low glycemic index, meaning it does not spike your blood sugar. 

Whether white, yellow, or red onions, onion extract, or onion juice, onions are a versatile vegetable to incorporate into your diet in many ways to help manage your diabetes mellitus and its related complications.

Written by Edibel Quintero, RD
Edibel Quintero is a medical doctor who graduated in 2013 from the University of Zulia and has been working in her profession since then. She specializes in obesity and nutrition, physical rehabilitation, sports massage and post-operative rehabilitation. Edibel’s goal is to help people live healthier lives by educating them about food, exercise, mental wellness and other lifestyle choices that can improve their quality of life.
The article was fact checked by Rosmy Barrios, MD
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Written by Edibel Quintero, RD
Fact checked by Rosmy Barrios, MD
Last update: March 31, 2023
8 min read 1514 Views 0 Comments

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