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Watermelon and Blood Sugar: Uncover the Glycemic Index of this Fruit

Madison Holt, MS, RDN, LD

Published in Nutrition

8 min read

August 9, 2022
a group of people eating watermelon with spoons
a group of people eating watermelon with spoons

Watermelon is a refreshing, sweet, and hydrating fruit that makes for a great summertime treat. 

This fruit has been part of the human diet for thousands of years. You may be surprised to know that the watermelon was even present in ancient hieroglyphics in Egypt and India! 

Today, however, there are over 1,200 varieties of watermelon around the world, and the U.S. and Mexico grow around 200-300 of them. 

The flesh of the watermelon can be pink or red, yellow, or even white and can be eaten fresh, in smoothies, or even made into fruit juice. True to its name, watermelons are 92 percent water, and are actually a type of berry. 

So, what health benefits does this tasty fruit have, and how does it affect your glucose levels? Let’s find out. 

The Nutritional Benefits of Watermelon

The Dietary Guidelines for Americans recommends eating 1.5 - 2.5 cups of fruit per day. 

Fruits are great sources of nutrients like fiber, vitamins, potassium, folate and antioxidants. These nutrients can contribute towards improved heart health, immune system health, and digestive health. 

watermelon nutrition facts chart

As we mentioned before, the high water content found in this fruit means that it can help improve hydration too. Let’s take a deeper look at the health benefits of the nutrient found in watermelon.


Most Americans don’t get enough potassium in their diets. Watermelon is high in potassium, a mineral that your body relies on for proper kidney, heart, and nervous system function. This mineral may also counter the effects of sodium to help improve blood pressure.

Vitamin A

watermelon slices

The typical serving size of watermelon (one cup diced) contains 33 percent of your daily recommended amount of vitamin A. This vitamin is crucial to your immune function, vision, and growth and development. It supports cell growth, and plays a crucial role in maintaining your heart, lungs, eyes, among other organs. 

A 2017 study found that higher dietary intake of vitamin A may also be associated with a lower risk of bone fractures, though more research is still needed.

Vitamin A may also reduce the risk of cancer, particularly in your head and neck, and Vitamin A deficiency has been associated with an increased risk of cancer. While this is promising research, the relationship between vitamin A and cancer is still not completely clear. 

Vitamin C

One serving of watermelon has 39 percent of your daily recommended amount of vitamin C. Vitamin C is required for the production of collagen, which supports healthy skin, bones, tendons, and connective tissue. 

As an antioxidant, vitamin C helps fight off free radicals in your body that can damage your cells and DNA .It also supports immune system function, wound healing, joint health, and helps decrease the risk of infection.

Vitamin C may also play a role in regulating blood sugar and blood pressure. A 2019 study examined a group of 31 people above the age of 60 with type 2 diabetes to see how vitamin C supplements affected their blood sugar after meals. 

The study found that vitamin C significantly decreased their daily post-meal blood glucose levels and blood pressure after 4 months of the study. 


watermelon slices

L-citrulline is an amino acid found in watermelons. Studies have found that citrulline may reduce the risk of cardiovascular disease by improving blood pressure. Animal studies have shown that it may play a role in protecting against endothelial dysfunction, a coronary artery disease. 

However, many studies on L-citrulline have been short-term and pre-clinical, meaning that  more research is still needed to determine a definitive link between L-citrulline and heart health.  


Watermelon contains lycopene, an antioxidant that gives watermelon its color. This antioxidant targets free radicals that harm your cells and may play a role in reducing the risk of diabetes, high cholesterol, neurodegenerative diseases, prostate cancer, and heart disease. 

Lycopene is the source of a lot of promising research, but more study is needed to understand exactly how lycopene affects us.

Watermelon and Blood Glucose

watermelon slices

So, watermelon is full of lots of beneficial vitamins and minerals for your overall health. But how does it affect blood sugar? And is it a safe option for individuals with diabetes or anyone following a diabetes diet?

One serving of watermelon contains about 18 grams of sugar. This amount of sugar can have an impact on your blood sugar, but its effect largely depends on the amount of watermelon you’re eating. Consuming watermelon after eating a source of fiber or protein can also help prevent your big spikes in blood sugar. 

Watermelon has a glycemic index, or GI, of 80, which is considered a high GI.However, because watermelon is relatively low in carbohydrates, one serving of this fruit has a glycemic load (GL) of five, meaning that consuming a small amount may not lead to a sharp blood sugar spike.

In fact, foods with low GL may be safer for blood sugar in small amounts. In the case of watermelon, its moderate dietary fiber content may also help blunt any glucose response that may arise after consuming it.

The GI and GL systems are just one tool for helping you know what’s healthy and safe for you to eat. If you are unsure about whether you should add watermelon to your diet, talk to your doctor or credentialed dietitian.

Adding Watermelon To Your Diet

Watermelon can be a nutritious and delicious treat on its own, but there are many other ways to eat it. The whole fruit is edible — even the rind!  

To pick the perfect watermelon, opt for one that is firm and free of dents, scratches, or bruises. It should be heavy, and have a yellow spot on its underside to indicate that it was given time to ripen.

Here are five interesting ways to incorporate more watermelon into your diet.

5 New Ways to Try Watermelon

1) Watermelon Gazpacho from Love and Lemons

a person making watermelon gzpacho

Gazpacho is a traditional Spanish cold tomato soup enjoyed in the summer months. This version adds watermelon to the mix, making it a hydrating and refreshing meal for a hot summer day. 

It also contains cucumber, a great source of potassium, and vitamin C-rich tomatoes and bell pepper. Consider adding the avocado for a boost of antioxidants and nutritious fats.

  • 4 heaping cups cubed, seedless watermelon
  • 1 English cucumber, diced
  • 3 medium tomatoes, diced
  • 1 small red bell pepper, diced
  • ⅓ cup chopped green onions, diced
  • 1 garlic clove
  • A small handful basil
  • 3 to 4 tablespoons red wine vinegar
  • 3 tablespoons olive oil, plus more for drizzling
  • 1 to 2 teaspoons sea salt, or to taste
  • ½ teaspoon freshly ground black pepper
  • ½ jalapeño pepper, optional
  • Diced avocado, optional
  • Microgreens, optional for garnish

2) Watermelon Cucumber Salad from A Couple Cooks

a plate of watermelon cucumber salad

This simple and refreshing salad combines feta cheese with watermelon for a perfect blend of salty and sweet. 

Feta cheese contains 260 milligrams of sodium per ounce, so keep that in mind if you’re watching your sodium intake. Enjoy this tasty salad after spending time in the pool to give you a boost of electrolytes and antioxidants.

  • 8 cups cubed ripe, seedless watermelon
  • 2 organic mini cucumbers or ½ English cucumber
  • 2 ounces Feta cheese crumbles
  • Zest of ½ lemon
  • 4 basil leaves
  • Sea salt, for garnish

3) Watermelon Rind Pickles from Alton Brown

If you’re wondering how to eat a watermelon rind, give these watermelon rind pickles a try. Like any pickle, you can eat these on their own or even add them to a salad for an extra crunch. 

Plus, the apple cider vinegar makes this a great snack for balancing your blood sugar!

  • 2 pounds watermelon rind, from a 5-pound watermelon
  • 1 cup apple cider vinegar
  • 1 cup water
  • ¾ cup sugar
  • ¼ cup chopped candied or crystalized ginger
  • 4 teaspoons kosher salt
  • 1 teaspoon red pepper flakes
  • 1 teaspoon allspice berries
  • 1 star anise pod

4) Watermelon Blueberry Salsa from Love and Olive Oil

a bowl of watermelon blueberry salsa

This twist on a classic salsa is full of antioxidants and delicious flavor. From the tomatoes to the blueberries to the watermelon, it makes for a sweet and spicy dip for your favorite dippers.

  • 4 small Roma tomatoes, roughly chopped
  • 1/2 small onion, chopped
  • 1 jalapeno, chopped
  • 1 cup diced watermelon
  • 1/2 cup fresh blueberries
  • 3 tablespoons chopped fresh cilantro
  • 3 tablespoons lime juice
  • 1/4 teaspoon salt

5) Watermelon, Feta, and Basil Quinoa from How Sweet Eats

a plate of watermelon with quinoa

This recipe brings back the sweet and salty combo we love, this time adding some quinoa, a nutritious protein and fiber-rich grain that may have a positive effect on blood sugar and blood pressure. 

  • 1 cup uncooked quinoa, rinsed
  • ¾ teaspoon salt
  • ¼ teaspoon pepper
  • 1 ½ cups chopped fresh watermelon
  • 1 tablespoon honey
  • ⅔ cup crumbled feta cheese
  • 15-20 basil leaves, chopped
  • Juice of 1 lime
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Amanda Donahue, MS, RD, CD

Reviewed by: Amanda Donahue, MS, RD, CD

Amanda is a Nutrition Manager and Registered Dietitian at Nutrisense, with a Masters in Dietetics from Stephen F. Austin State University. Originally from south GA, she got her undergrad degree from Texas Tech University. Before joining Nutrisense, she worked at a hospital in Fort Worth, TX, for 4 years as a dietitian, counseling those living with HIV.