Beans and Diabetes: Carbs, Glycemic Index and Portions
A half cup of cooked black beans has about 20 g of carbohydrate (13 g net). Glycemic index: low (23 to 32). Yes. Beans bring carbohydrate, fiber and protein together and are widely recommended, in measured portions.
Beans count as a starch, but they come with a lot of fiber and plant protein, and they digest slowly. They are one of the most useful foods to rely on in a diabetes meal plan, especially for vegetarian meals.
Canned beans are convenient. Rinse them to cut sodium, and check that they have no added sugar, which baked-bean style cans often do.
Carbs in beans by portion
| Portion | Grams | Carbs (g) | Fiber (g) | Net carbs (g) | Protein (g) |
|---|---|---|---|---|---|
| 0.5 cup | 86 | 20 | 7.5 | 13 | 7.7 |
| cup | 172 | 41 | 15 | 26 | 15 |
| 100 g (for comparing foods) | 100 | 24 | 8.7 | 15 | 8.9 |
Source: USDA FoodData Central, FDC ID 173735 (Black beans, cooked). 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 tables have no black bean entry, so these values are for kidney, navy and black-eyed beans, the nearest cooked beans listed. 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.
No black bean entry in the tables. These are other cooked dried beans (kidney, navy), shown as the closest published values.
Which published values we used (4)
| Entry | Food as listed | GI |
|---|---|---|
| Suppl. Table 2, #3118 | Haricot/Navy beans, boiled in water with 2 g salt | 31 |
| Suppl. Table 2, #3125 | Kidney beans, dried, boiled | 23 |
| Suppl. Table 2, #3127 | Kidney beans, boiled in water with 2 g salt | 29 |
| Suppl. Table 2, #3128 | Kidney beans, boiled in salted water | 32 |
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 beans fit the plate method
Beans 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 beans onto a meal in the meal planner to watch the plate fill.
Portion ideas and pairings
- A half cup cooked is a common serving.
- Add them to salads and soups to replace some of the rice or pasta.
- Mash them into a spread for a sandwich instead of mayonnaise.
Pairs well with: rice in a smaller portion, a big pile of vegetables, salsa and avocado.
Related foods
Egg, hard-boiled
1 large: 0.6 g carbs
Banana
1 medium: 27 g carbs
Apple
cup, quartered or chopped: 17 g carbs
Sweet potato
cup, cubes: 27 g carbs
See all foods and the low glycemic foods list
Frequently asked questions
Do beans raise blood sugar?
They contain carbohydrate, so they do raise it, but gradually, thanks to fiber. Count them as part of the meal.
How many carbs are in a half cup of cooked black beans?
About 20 g of carbohydrate, of which about 7.5 g is fiber, so roughly 13 g net carbs. Values are from USDA FoodData Central for 86 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: Black beans, cooked (FDC ID 173735)
- 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.
