Watermelon: GI, GL, Carbs & Blood Sugar Impact
Glycemic index of watermelon (76), glycemic load, carbs per serving, and why high GI watermelon can still fit a diabetes diet.
Does Watermelon Raise Blood Sugar?
Watermelon has a high published GI (around 76), which surprises people — but a serving is mostly water. Two cups carry about 21 g of carbohydrate, giving a moderate GL. GI alone overstates its impact; the portion is what decides.
How to Eat It
Keep the portion around a cup or two, and treat it as part of the day’s carbohydrate budget. Eating it after a protein-containing meal further flattens the response.
Nutrition Facts (Watermelon)
| Nutrient | Per 100 g | Per serving |
|---|---|---|
| Calories | 30 kcal | 84 kcal |
| Carbohydrate | 7.6 g | 21.3 g |
| Fiber | 0.4 g | 1.1 g |
| Sugars | 6.2 g | 17.4 g |
| Protein | 0.6 g | 1.7 g |
| Fat | 0.2 g | 0.6 g |
Source: USDA FoodData Central (generic food item, per 100 g edible portion). Values may differ from brand-specific products.
Glycemic Index
Published GI: 76 (typical value).
Reported range: 72-80.
Evidence level: Moderate.
Note: High GI but mostly water - the per-serving carbohydrate load stays moderate at a normal portion.
Sources: International Tables of Glycemic Index and Glycemic Load Values (2008/2021); University of Sydney GI Database (glycemicindex.com). GI values are reported relative to a glucose reference.
Learn more: What is GI? · What is GL? · GI vs GL
Estimated Glycemic Load
GL ≈ 15.3 per 2 cups diced (280 g).
Calculation: GI (76) × available carbohydrate per serving (20.2 g = 7.6 g − 0.4 g fiber) ÷ 100. Calculated by DMSafeHaven; formula per standard published GL methodology.
- Portion size
- How ripe the melon is
- Eating it alone vs. after a protein-containing meal
GI values can vary with variety, ripeness, preparation and testing conditions. The value above is a typical published figure, not a universal prediction for every individual or every serving.