Whole wheat bread glycemic index and glycemic load
Whole wheat bread has a high glycemic index of 75 (the median of 9 lab tests, range 59 to 88) in the 2021 International Tables, where pure glucose is 100. A serving of 1 slice (1.1 oz, 32.1 g) has 11.9 g of carbs minus fiber, which gives a glycemic load of about 9.
Glycemic load by portion
| Portion | Carbs | Fiber | Carbs minus fiber | Glycemic load |
|---|---|---|---|---|
| 1 slice (1.1 oz, 32.1 g) | 13.8 g | 1.9 g | 11.9 g | 9 |
| 1 oz (28 g) | 12.2 g | 1.7 g | 10.5 g | 8 |
Glycemic load = GI 75 × carbs minus fiber ÷ 100. Carbs from USDA FoodData Central, Bread, whole-wheat, commercially prepared.
Every standardized test
| Food as tested | GI | Category | Country |
|---|---|---|---|
| Whole wheat wheat flour bread, sliced (Pan Bauletto Integrale, Italy) | 59 | medium | Italy |
| Whole wheat bread (whole wheat wheat flour, water, yeast, salt, and 40% sourdough), baked at 392°F... | 61 | medium | Spain |
| Whole wheat bread, smooth milled, Ploughman's™ (Quality Bakers, Australia) | 64 | medium | Australia |
| Whole wheat flour bread | 69 | medium | China |
| Whole wheat flour bread | 75 | high | Australia |
| Whole wheat flour bread, short whole wheat (50% whole meal wheat, 50% white wheat, Baker’s yeast... | 78 | high | New Zealand |
| Whole wheat bread, long whole meal (50% whole meal wheat, 50% white wheat, Baker’s yeast (13% net... | 80 | high | New Zealand |
| Whole wheat bread (Gardenia Bakeries (KL) Sdn Bhd Shah Alam, Selangor, Malaysia) | 85 | high | Malaysia |
| Whole wheat bread, yeast (50% whole wheat wheat, 50% white wheat, Baker’s yeast (15% dry weight), 60... | 88 | high | New Zealand |
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).
Compared with similar foods
| Food | GI | Portion | Carbs minus fiber | Glycemic load |
|---|---|---|---|---|
| Corn tortilla | 49 | 1 oz (28 g) | 10.9 g | 5 |
| Pita bread | 62 | 1 pita, large (2.1 oz, 60 g) | 32.1 g | 20 |
| White bread | 71 | 1 slice (1 oz, 27.3 g) | 12.8 g | 9 |
| Sourdough bread | 72 | 1 oz (28 g) | 14.1 g | 10 |
| Whole wheat bread | 75 | 1 slice (1.1 oz, 32.1 g) | 11.9 g | 9 |
Same group in the International Tables (Bread), 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
17 more tests of whole wheat bread are listed in the tables' second list (65 to 96, median 72). 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 17 tests
| Food as tested | GI | Country | Who was tested |
|---|---|---|---|
| Whole wheat bread | 65 | Canada | type 2 diabetes, 6 people |
| Whole wheat bread | 66 | Germany | diabetes |
| Whole wheat bread | 67 | Canada | type 2 diabetes, 11 people |
| Whole wheat bread | 68 | Canada | type 1 and type 2 diabetes, 15 people |
| Whole wheat bread | 70 | Canada | type 1 diabetes, 5 people |
| Whole wheat bread | 70 | Canada | type 2 diabetes, 6 people |
| Whole wheat bread, Helga's™ Traditional (Quality Bakers, Australia) | 70 | Australia | healthy, 8 people |
| Whole wheat flour bread | 72 | Canada | type 2 diabetes, 6 people |
| Whole wheat bread | 72 | Denmark | type 1 diabetes, 7 people |
| Whole wheat bread | 75 | Canada | type 2 diabetes, 9 people |
| Whole wheat bread | 75 | Australia | healthy, 7 people |
| Whole wheat bread (Barilla G.eR. Fratelli S.p.A., Parma, Italy) | 75 | Italy | healthy, 10 people |
| Whole wheat bread, commercially-manufactured | 77 | Sri Lanka | healthy, 10 people |
| Whole wheat bread (Tip Top Bakeries, Australia) | 77 | Australia | healthy, 8 people |
| Whole wheat bread (Tip Top Bakeries, Australia) | 78 | Australia | healthy, 7 people |
| Whole wheat bread | 88 | Kenya | type 2 diabetes, 9 people |
| Whole wheat bread | 96 | Canada | overweight, 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 whole wheat bread and blood sugar
- Level B In 39 adults with prediabetes on fully controlled diets, 2 weeks of whole wheat bread instead of white bread cut the post-meal glucose rise by 27%. Pierson JT et al., Front Nutr 2026
- Level B In 10 overweight adults, finely ground whole wheat bread gave no lower blood sugar response than white bread, and sourdough bread gave a lower response than the whole wheat bread. Br J Nutr, 2009
- Level B In 121 people with type 2 diabetes, 3.5 oz (100 g) of whole wheat, bran or rye bread raised blood sugar about as much as white bread. Diabetes Res Clin Pract, 2008
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, Foundation Foods (release 2025-12-18): Bread, whole-wheat, commercially prepared, FDC ID 335240
- USDA FoodData Central, SR Legacy (2018): Tortillas, ready-to-bake or -fry, corn, FDC ID 175036
- USDA FoodData Central, SR Legacy (2018): Bread, pita, white, enriched, FDC ID 174915
- USDA FoodData Central, Foundation Foods (release 2025-12-18): Bread, white, commercially prepared, FDC ID 325871
- USDA FoodData Central, SR Legacy (2018): Bread, french or vienna (includes sourdough), FDC ID 172675
- 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.