Sweet Potatoes and Diabetes: Carbs, Glycemic Index and Portions
One sweet potato, about 5 inches long has about 26 g of carbohydrate (22 g net). Glycemic index: low to high (48 to 94). Yes, in measured portions. Sweet potatoes are a starchy vegetable, so they count toward the carbohydrate part of your plate.
Sweet potatoes bring fiber and a lot of flavor, and they are a favorite swap for white potatoes. They are still a starchy vegetable, so they belong in the carbohydrate quarter of the plate method, not the non-starchy half.
How you cook one changes how fast it raises glucose. Studies report quite different glycemic index values for boiled, baked and roasted sweet potatoes, which is why the range below is wide. Boiling or steaming tends to give lower values than baking.
Carbs in sweet potatoes by portion
| Portion | Grams | Carbs (g) | Fiber (g) | Net carbs (g) | Protein (g) |
|---|---|---|---|---|---|
| cup, cubes | 133 | 27 | 4 | 23 | 2.1 |
| sweetpotato, 5" long | 130 | 26 | 3.9 | 22 | 2.1 |
| 100 g (for comparing foods) | 100 | 20 | 3 | 17 | 1.6 |
Source: USDA FoodData Central, FDC ID 168482 (Sweet potato). Net carbs here means carbohydrate minus fiber. “Net carbs” is not an FDA-defined term, so total carbs are shown too. Values are estimates for a typical item; brands, ripeness and size vary.
Glycemic index and glycemic load
GI ranks how fast a food raises blood glucose compared with pure glucose (100). Low is 55 or less, medium 56 to 69, high 70 or more. Boiled, baked and roasted sweet potato were tested separately, so values differ a lot. Glycemic load multiplies the index by the available carbohydrate in a portion (carbs minus fiber), so it reflects how much you actually eat: low is 10 or less, medium 11 to 19, high 20 or more.
Which published values we used (4)
| Entry | Food as listed | GI |
|---|---|---|
| Suppl. Table 1, #1884 | Sweet potato (Ipomoea batatas), NS, peeled, baked 45 min | 94 |
| Suppl. Table 1, #1899 | Sweet potato, kumara, cooking method NS | 77 |
| Suppl. Table 2, #3664 | Sweet potato, boiled in water with 2 g salt | 48 |
| Suppl. Table 2, #3667 | Sweet potato, orange | 77 |
Atkinson FS et al. International tables of glycemic index and glycemic load values 2021. Am J Clin Nutr 2021;114(5):1625-1632. Glucose reference (glucose = 100); values from studies that used white bread were converted by the authors. Where studies differ we show the range, not an average.
Glycemic index is only one piece of the picture. The same food can give a different response depending on ripeness, cooking, what you eat it with and your own body, so your meter or CGM is the best guide.
How sweet potatoes fit the plate method
Sweet Potatoes count toward the carbohydrate quarter of the plate in the plate method, along with grains, starchy vegetables, fruit and milk. The CDC describes the plate method as half non-starchy vegetables, a quarter protein and a quarter carbohydrate foods. See the diabetic meal plan guide for how it works, or drop sweet potatoes onto a meal in the meal planner to watch the plate fill.
Portion ideas and pairings
- A small sweet potato or a half cup mashed is a typical serving.
- Leave the skin on for extra fiber.
- Go easy on brown sugar, marshmallows and syrup toppings, which add a lot of carbohydrate.
Pairs well with: grilled chicken or fish, a big side of green beans or broccoli, a spoonful of plain yogurt instead of butter and sugar.
Related foods
Potato
Potato medium: 37 g carbs
White rice, cooked
cup: 45 g carbs
Quinoa, cooked
cup: 39 g carbs
Corn, sweet
cup: 27 g carbs
See all foods and the low glycemic foods list
Frequently asked questions
Are sweet potatoes better than white potatoes for diabetes?
They have a bit more fiber and vitamin A, but the carbohydrate is similar and the cooking method matters as much as the type. Portion size is the bigger lever for both.
How many carbs are in one sweet potato, about 5 inches long?
About 26 g of carbohydrate, of which about 3.9 g is fiber, so roughly 22 g net carbs. Values are from USDA FoodData Central for 130 g and are estimates; brands and sizes vary.
Information only, not medical advice. Your care team may set different targets for you, and only a lab test ordered by a clinician can diagnose diabetes or prediabetes. See our medical disclaimer.
Sources
- USDA FoodData Central: Sweet potato (FDC ID 168482)
- Atkinson FS et al. International tables of glycemic index and glycemic load values 2021. Am J Clin Nutr 2021;114(5):1625-1632
- CDC: Diabetes Meal Planning (plate method and carbohydrate counting)
- ADA Standards of Care in Diabetes—2026, Section 5: Facilitating Positive Health Behaviors
Last reviewed: by the Diabetes Blogs editorial team. Information only, not medical advice.
