Oats & breakfast cereals · Glycemic index

Does oatmeal (rolled oats) spike blood sugar?

Moderately. Oatmeal (rolled oats) has a medium GI of 58, and a 240 g serving (1 cup cooked) has a medium glycemic load of 13. Porridge made from rolled oats sits at the low end of the medium GI band — far gentler than instant oats, though not quite as low as steel-cut.

Key numbers

Glycemic index: 58; Medium GI
Glycemic load: 13; Medium GL
Available carbs: 23 g; 4.1 g fiber
Serving: 1 cup cooked; 240 g · porridge cooked in water

GI vs GL for oatmeal (rolled oats)

The glycemic index (GI) compares how fast the carbohydrate in a food raises blood sugar against pure glucose (100), using a fixed amount of carbohydrate. The glycemic load (GL) adds the other half of the story — how much carbohydrate a normal serving actually contains: GI × available carbs ÷ 100. For oatmeal (rolled oats): 58 × 23 g ÷ 100 ≈ 13.

That figure is an average reported in the 2021 international GI tables (“Porridge made from rolled oats, mean of eight foods”). Rolled-oat porridge varies with flake thickness and processing; in the 2008 tables, 13 rolled-oat porridge studies averaged 55, and thick flakes generally tested lower than thin, heavily processed ones.

Eating a different amount? Work out the glycemic load of your portion.

How to eat oatmeal (rolled oats) with less of a spike

Buy old-fashioned (thick) rolled oats rather than quick oats; thicker, less-processed flakes tested lower in GI studies.
Sweeten with a handful of berries instead of sugar, honey or syrup.
Stir in nut butter, chopped nuts or seeds — meals containing fat are converted into blood sugar more slowly.

Lower-GI swaps

Compare with

See all 67 foods in the glycemic index table

Frequently asked questions

What is the glycemic index of oatmeal (rolled oats)?

Oatmeal (rolled oats) has a glycemic index of 58, which is medium. That figure is an average reported in the 2021 international GI tables (“Porridge made from rolled oats, mean of eight foods”). A 240 g serving (1 cup cooked) contains about 23 g of available carbohydrate, giving a glycemic load of 13 (medium).

Is oatmeal (rolled oats) good for prediabetes?

Oatmeal can be a good breakfast for prediabetes if you choose less-processed oats and keep sugary toppings small. Old-fashioned rolled oats or steel-cut oats beat instant packets; top the bowl with nuts or seeds and fruit rather than brown sugar or syrup.

What is the difference between rolled, steel-cut and instant oats for blood sugar?

They are the same whole grain processed to different degrees — cut, flattened, or rolled thin and precooked. In the 2021 international tables, porridge averaged a GI of 52 from steel-cut oats, 58 from rolled oats and 82 from instant oats.

Sources

GI values come from the international GI tables; carbohydrate and fiber per serving are calculated from USDA FoodData Central.

Data last checked September 30, 2026.