Carbs in Watermelon: Is It Good for Diabetics?

Carbs in watermelon

Portion	Carbs	Fiber	Net carbs	Sugar	Calories
1 cup, diced152 g	11 g	1 g	11 g	9 g	46
Wedge (1/16 of a melon)286 g	21 g	1 g	20 g	18 g	86
10 melon balls122 g	9 g	0 g	9 g	8 g	37

Per 100 g: 7.5 g carbs, 0.4 g fiber, 0.6 g protein, 0.1 g fat, 30 calories. Source: USDA FoodData Central (Watermelon, raw). Net carbs = carbs minus fiber. Brands and recipes vary, so check the label when you have one.

The short version

A cup of diced watermelon (152 g) has about 11 g of carbs, almost all of it sugar. A big wedge has about 21 g.
Yes, people with diabetes can eat watermelon. It is mostly water, so a normal portion carries fewer carbs than a slice of bread.
Its sugar is absorbed fast. Watermelon has a high glycemic index but a low glycemic load, so the size of the portion decides most of the rise.
Measure a cup instead of eating from the melon, and have it with a meal or some protein rather than on its own.

How many carbs are in watermelon?

Watermelon is about 90% water, which keeps the carbs per bite low. USDA data for raw watermelon gives 7.5 g of carbs per 100 g. For the portions people actually eat:

10 melon balls (122 g): about 9 g of carbs
1 cup, diced (152 g): about 11 g of carbs
One wedge, 1/16 of a melon (286 g): about 21 g of carbs

The wedge is where people get caught. A triangle cut from a large melon at a barbecue can easily weigh more than USDA's 286 g, and two of them put you past 40 g of carbs. A whole melon of about 4.5 kg holds over 300 g of carbs, so a quarter of one is a full meal's worth.

There is very little fiber to subtract: about half a gram per cup. If your care team has you count net carbs, the number barely changes. Of the 11 g in a cup, about 9 g is sugar. New to counting? Our carb counting guide covers portions, labels and fiber.

Is watermelon good for diabetics?

It can be. Watermelon is a whole fruit with no added sugar, it has some vitamin C and potassium, and a cup is only about 46 calories. For a sweet craving, a measured cup is a much smaller carb load than a dessert or a glass of juice.

The downside is that it has almost no fiber, protein or fat, the things that slow digestion. So the carbs it does have arrive quickly. The American Diabetes Association doesn't ban any fruit. Its nutrition guidance focuses on the total carbs you eat and on choosing whole foods, and whole fruit counts as a good choice when the portion fits your plan.

What watermelon does to blood sugar

You may have read two numbers about watermelon that seem to disagree. In the international glycemic index tables, watermelon has a glycemic index of about 72, which is high. The GI measures how fast a fixed amount of carbs raises blood sugar, and watermelon's sugar is absorbed quickly.

But the same tables give a glycemic load of only about 4 for a 120 g serving, which is low. Glycemic load takes the portion into account, and a normal serving of watermelon simply doesn't contain many carbs. So a cup of watermelon is likely to raise you quickly, but not very far.

Two things tend to make the spike bigger: eating it on an empty stomach, and eating a lot of it. Watermelon is easy to keep eating because it's light and cold. If you have it alone as a snack, many people see a quick, early rise. Eaten after a meal, the rise is usually slower and flatter.

Your own meter or CGM is the best guide. Check before you eat and again about 2 hours after you start. Our article on blood sugar 2 hours after eating explains what the reading means.

How to eat watermelon with diabetes

Measure it into a bowl. One cup diced is a sensible serving. Eating straight from a big slice makes it hard to know how much you had.
Pair it with protein or fat. A handful of nuts, some feta cheese, Greek yogurt or a meal of chicken or fish slows the rise compared with watermelon on its own.
Skip watermelon juice and smoothies. Blending removes nothing, but it makes it easy to drink two or three cups' worth of carbs in a minute.
Watch the add-ons. Watermelon cocktails, sorbet and fruit salads with syrup or honey add sugar on top of the fruit's own.
Count it as fruit, not as water. On a hot day it's tempting to treat it as a drink. It still has carbs.
Use it to treat a low only if your plan allows. Because it acts fast, some people reach for it, but it's hard to dose a set number of grams from fruit. Glucose tablets or juice are easier to measure.

If you take insulin Count the carbs in your portion as you would for any fruit. How much insulin to take for it, and when, should come from your doctor or diabetes educator, not from an article. Ask your care team if watermelon tends to rise faster than your insulin works.

Counting it without a scale

At a picnic you won't weigh your watermelon. In T1dApp you can take a photo of your plate and get the carbs for each food on it, shown as a range you can edit. Two hours later the app asks for your reading, so you see how watermelon, in the portions you actually eat, affects you. For other foods that fit easily into a day, see our low-carb meals for diabetes.

Snap your meal, see the carbs

T1dApp gives you carbs, calories, protein and fat from a photo, and your likely blood sugar 2 hours later.

Get T1dApp

Sources

This article is general information, not medical advice. Your targets, doses and diet should be set with your doctor or diabetes care team.

Carbs in watermelon, and is it good for diabetics?