Potatoes and Diabetes: Carbs, Glycemic Index and Portions
A medium potato has about 37 g of carbohydrate (33 g net). Glycemic index: low to high (41 to 94). Yes, in measured portions. Potatoes are not off-limits; they are a starchy vegetable, so the portion and what goes with them matter.
Potatoes are comfort food in many kitchens, and nothing says a person with diabetes has to give them up. A medium potato is a decent amount of carbohydrate, though, so it usually takes up the carbohydrate quarter of the plate on its own.
Cooking and form change the effect. Boiled, baked, mashed and fried potatoes can behave differently, and the published glycemic index values for potatoes cover a very wide range, as the table shows. Eating the skin adds fiber.
Carbs in potatoes by portion
| Portion | Grams | Carbs (g) | Fiber (g) | Net carbs (g) | Protein (g) |
|---|---|---|---|---|---|
| Potato medium | 213 | 37 | 4.5 | 33 | 4.3 |
| 0.5 cup, diced | 75 | 13 | 1.6 | 12 | 1.5 |
| Potato large | 369 | 65 | 7.7 | 57 | 7.4 |
| 100 g (for comparing foods) | 100 | 18 | 2.1 | 15 | 2 |
Source: USDA FoodData Central, FDC ID 170026 (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. The values range widely because baked, boiled, steamed and mashed potatoes were all tested. 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 (5)
| Entry | Food as listed | GI |
|---|---|---|
| Suppl. Table 1, #1842 | Potato, NS, boiled | 66 |
| Suppl. Table 1, #1873 | Potato, NS, steamed | 62 |
| Suppl. Table 2, #3605 | Potatoes, NS, baked for 30 min | 78 |
| Suppl. Table 2, #3624 | Potatoes, white, NS, cooked | 41 |
| Suppl. Table 2, #3659 | Potatoes, NS, steamed in high heat for 35 min | 94 |
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 potatoes fit the plate method
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 potatoes onto a meal in the meal planner to watch the plate fill.
Portion ideas and pairings
- A small to medium potato, not a very large baker.
- Share an order of fries rather than eating a full one.
- Skip heavy toppings, or swap sour cream for plain yogurt.
Pairs well with: a non-starchy vegetable like green beans or broccoli, a lean protein such as chicken or fish, a green salad with olive oil.
Related foods
Sweet potato
cup, cubes: 27 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
Can I eat french fries?
Occasionally and in a small portion, if your care team agrees. Fries add fat as well as carbohydrate, and a restaurant portion is often several servings.
How many carbs are in a medium potato?
About 37 g of carbohydrate, of which about 4.5 g is fiber, so roughly 33 g net carbs. Values are from USDA FoodData Central for 213 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: Potato (FDC ID 170026)
- 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.
