Watermelon is a refreshing summer fruit that contains plenty of natural sugar. While it is usually safe for people with diabetes to include watermelon in their diet, several factors determine the portion size and frequency of consumption.

People with diabetes have to be careful about their food choices to maintain stable blood sugar levels and avoid complications.

A diet high in fruits and vegetables can support blood sugar management. However, as fruit also contains natural sugars and carbohydrates, working out a suitable serving size is essential.

The American Diabetes Association (ADA) advise that "as there is no single ideal dietary distribution of calories among carbohydrates, fats, and proteins for people with diabetes, macronutrient distribution should be individualized while keeping total calorie and metabolic goals in mind."

In this article, we look at the nutritional benefits of watermelon and discuss what people with diabetes may need to consider before including this fruit in their diet.

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Watermelon has a high GI, so people with diabetes should moderate their intake.

When looking at the dietary effect of watermelon or any other food in people with diabetes, the glycemic index (GI) is an important indicator of how it may potentially alter blood glucose levels.

The GI is a measure of how quickly sugar from food enters the bloodstream. The faster this happens, the more likely it is that a person will have a blood sugar spike.

The GI system allocates each food a score between 1 and 100. The higher the number, the greater the speed at which sugar enters the bloodstream.

Watermelon has a GI of around 76. Any food item with a GI of 70 or above has a high GI. People with diabetes should, therefore, carefully moderate their watermelon consumption.

Additionally, people who have diabetes should try to eat watermelon alongside foods that are rich in healthful fats, fiber, and protein, such as nuts and seeds. This combination of nutrients can help people feel full for longer and reduce the effect of watermelon on blood glucose levels.

Watermelon is an excellent source of many vitamins and minerals, including:

Vitamin A helps preserve function in the heart, kidneys, and lungs. It also supports eye health. The United States Department of Agriculture (USDA) advise that one wedge of watermelon weighing roughly 286 g provides 80 retinol activity equivalents (RAE), a measurement of vitamin-A intake.

The Office of Dietary Supplements (ODS) advise that men aged over 14 years should consume 900 RAE and women should take in 700 RAE of vitamin A. This means that one wedge of watermelon can contribute just over 10% of a person's recommended daily vitamin A allowance.

Vitamin C is a powerful antioxidant that promotes a healthy immune system. A strong immune system can reduce the frequency of illnesses and infections and may help prevent certain types of cancer.

The ODS also advise that men should consume 105.2 milligrams per day (mg/day), and that women should reach an intake of 83.6 mg/day.

A wedge of watermelon provides 23.2 mg of vitamin, meaning that it provides around 30.7% of the recommended daily vitamin C intake for women and 25.6% of the intake for men.

Fruits are often high in fiber. A high-fiber diet supports digestive function and helps the body flush out toxins. The ability of high-fiber foods to help a person feel full makes them a great choice for people who have diabetes as accurate portion control is a vital part of managing blood glucose levels.

More than 90% of watermelon consists of water, making it great for hydration. In addition, magnesium and potassium can improve blood circulation and aid kidney function. One wedge of watermelon provides around 320 mg of potassium.

The fruit also contains a nonessential amino acid called citrulline, which a 2018 review suggests can help improve blood pressure and metabolic health.

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Apples are a safe alternative to watermelon for people with diabetes.

A person with diabetes should aim to eat a balanced, healthful diet containing a large proportion of fruits and vegetables.

As the sugar in fruits occurs naturally, people with diabetes do not need to monitor their intake of fruit as closely as their intake of foods that contain added sugars.

However, it is still important for people with diabetes to be aware of the sugar and carbohydrate content of any fruits in a meal or snack. Similarly, they should avoid eating excessive amounts of fruit to prevent a spike in blood sugar levels.

Choosing fruits with lower levels of sugar and carbohydrates and higher amounts of fiber is advisable, as well as being careful about drinking sugary beverages, such as fruit juices and smoothies.

As a general rule, fruit with a lower carbohydrate content has a lower GI, so a person with diabetes can eat more of it.

Fruits that have a less significant effect on blood sugar levels include:

  • oranges
  • berries
  • apples
  • pears

Read about the relationship between fruit and diabetes here.

Watermelon is safe for people with diabetes to eat in small amounts. It is best to eat watermelon and other high-GI fruits alongside foods that contain plenty of healthful fats, fiber, and protein.

A doctor, dietitian, or diabetes educator can help a person with diabetes work out both their current glucose intake and how much they should be consuming.

They can also work with the person to develop a meal plan that helps them manage their blood sugar levels.

Q:

Are honeydew melons safer for people with diabetes than watermelon?

A:

Honeydew melon and watermelon are very close in their total carbohydrate and fiber content and their glycemic load.

Honeydew melon sits below watermelon in the glycemic index, ranking at 65 compared with 76 for watermelon. However, it is lower in fiber than watermelon.

It is likely that honeydew melon and watermelon will cause similar increases in blood sugar, especially if a person eats them in excess or without other foods.

Natalie Butler, RD, LD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.