Oatmeal glycemic index and glycemic load
Oatmeal has a medium glycemic index of 57 (the median of 7 lab tests, range 50 to 76) in the 2021 International Tables, where pure glucose is 100. A serving of 1 cup (8.3 oz, 234 g) has 24.1 g of carbs minus fiber, which gives a glycemic load of about 14.
Glycemic load by portion
| Portion | Carbs | Fiber | Carbs minus fiber | Glycemic load |
|---|---|---|---|---|
| 1 cup (8.3 oz, 234 g) | 28.1 g | 4 g | 24.1 g | 14 |
| 0.75 cup (6.2 oz, 175 g) | 21 g | 3 g | 18 g | 10 |
Glycemic load = GI 57 × carbs minus fiber ÷ 100. Carbs from USDA FoodData Central, Cereals, oats, regular and quick, unenriched, cooked with water (includes boiling and microwaving), without salt. USDA's entry is oats cooked with water, the way oatmeal is made at home.
Every standardized test
| Food as tested | GI | Category | Country |
|---|---|---|---|
| Porridge oats (Freedom Foods, Australia) | 50 | low | Australia |
| Porridge oats, traditional (Lowan Whole Foods, Australia) | 51 | low | Australia |
| Porridge oats | 55 | low | China |
| Porridge, Traditional Rolled Oats (Woolworths Select brand, Australia) | 57 | medium | Australia |
| Porridge (Hubbards, New Zealand) | 58 | medium | New Zealand |
| Porridge, Scottish, made with water | 63 | medium | UK |
| Oat porridge made from 0.5-0.6 mm thick rolled oat flakes, cooked for 10 min (Elovena, Raisio... | 76 | high | Finland |
The tables' own average for this food: 58 (mean of eight foods).
Glucose = 100. Low 55 or less, medium 56 to 69, high 70 or more (category cut-offs from the International Tables). Only tests that followed the ISO 26642:2010 method: at least 10 healthy adults, a portion with 25 or 50 g of available carbs (Supplemental Table 1).
What changes the number
The same food tested in different forms, from the tests above and the other standardized tests of oatmeal in the tables.
| Form in the test | Tests | Median GI | Range |
|---|---|---|---|
| Microwaved | 1 | 63 | — |
| Boiled | 1 | 76 | — |
| Form not stated | 5 | 55 | 50 to 58 |
Variety, ripeness, cooking time and the lab all move the result, which is why one food can span a wide range.
Compared with similar foods
| Food | GI | Portion | Carbs minus fiber | Glycemic load |
|---|---|---|---|---|
| Steel cut oats | 52 | 1 cup (8.3 oz, 234 g) | 24.1 g | 13 |
| Oatmeal | 57 | 1 cup (8.3 oz, 234 g) | 24.1 g | 14 |
| Instant oatmeal | 82 | 1 cup, cooked (8.3 oz, 234 g) | 23.3 g | 19 |
Same group in the International Tables (Breakfast cereals), each at its usual US portion. A low GI with a big portion can give a higher glycemic load than a high GI with a small one.
Older and smaller studies
12 more tests of oatmeal are listed in the tables' second list (49 to 81, median 63). They deviate from the ISO method: fewer than 10 people, people with diabetes, a different reference food or sampling time, or wide variation. They are not part of the number at the top.
Show the 12 tests
| Food as tested | GI | Country | Who was tested |
|---|---|---|---|
| Porridge, made from rolled oats cooked for 20 min | 49 | Canada | healthy, 6 people |
| Oat porridge made from roasted thick (1.0 mm) dehulled oat flakes | 51 | Sweden | healthy, 10 people |
| Oat porridge made from steamed thick (1.0 mm) dehulled oat flakes | 54 | Sweden | healthy, 10 people |
| Oat porridge made from raw thick (1.0 mm) dehulled oat flakes | 55 | Sweden | healthy, 10 people |
| Porridge, oat | 62 | Germany | diabetes |
| Porridge (Value, UK) | 63 | UK | healthy, 8 people |
| Porridge, organic | 63 | UK | healthy, 8 people |
| Porridge, oatmeal | 64 | Germany | type 2 diabetes |
| Oat porridge made from roasted thin (0.5 mm) dehulled oat flakes | 70 | Sweden | healthy, 10 people |
| Porridge, oat | 70 | Canada | type 2 diabetes, 6 people |
| Porridge, oat | 76 | USA | type 2 diabetes, 8 people |
| Oat porridge made from roasted and steamed thin (0.5 mm) dehulled oat flakes | 81 | Sweden | healthy, 10 people |
Supplemental Table 2 of the International Tables. NS means the study did not specify.
How much the glycemic index tells you
Researchers and health bodies do not agree on how much weight to give the glycemic index of single foods.
- Level E The World Health Organization examined the glycemic index, found it inconsistent, and refused to build guidance on it. Carbohydrate intake for adults and children: WHO guideline, 2023
- Level C A year after the World Health Organization set the glycemic index aside, a meta-analysis of cohorts each over a hundred thousand people linked high glycemic index diets to more diabetes, heart disease and death. Lancet Diabetes & Endocrinology, 2024
- Level C Glycemic index and glycemic load, the other two ways of judging carbohydrate, held up far worse than fiber in the same analysis. Reynolds et al., The Lancet, 2019
What studies found about oatmeal and blood sugar
- Level A Steel-cut oats and big rolled flakes sit at the low end of the glycemic scale. Instant oatmeal from a sachet sits at the high end, twenty points away, and the label on both says oats. Tosh and Chu, British Journal of Nutrition, 2015
- Level C In 10 healthy adults, thick 1.0 mm oat flakes gave a glycemic index of 70 to 78, while thin 0.5 mm flakes gave 88 to 118, no lower than white bread. J Nutr, 2000
- Level B In 9 men aged 65 to 70, rolled oats eaten raw as muesli or boiled as porridge raised blood sugar as much as white bread, while whole boiled oat kernels did not. Eur J Clin Nutr, 1995
Some studies above score foods against white bread, not glucose, as 100, so their numbers are not on the same scale as the ones at the top of this page. Levels: A is a meta-analysis of trials, B a randomized trial, C an observational study, D lab or animal work, E an expert position. How we grade evidence.
Keep exploring
Sources
- Atkinson FS, Brand-Miller JC, Foster-Powell K, Buyken AE, Goletzke J. International tables of glycemic index and glycemic load values 2021: a systematic review. Am J Clin Nutr 2021;114(5):1625-1632, Supplemental Table 1 and Supplemental Table 2, PMID 34258626, doi:10.1093/ajcn/nqab233 (accessed 2026-10-12)
- USDA FoodData Central, SR Legacy (2018): Cereals, oats, regular and quick, unenriched, cooked with water (includes boiling and microwaving), without salt, FDC ID 173905
- USDA FoodData Central, SR Legacy (2018): Cereals, oats, instant, fortified, plain, prepared with water (boiling water added or microwaved), FDC ID 171662
- Evidence cards: each study above links to its source. Card review dates are listed in our methodology.
Sources checked 2026-10-12. Bioma Learn provides information, not medical advice.