Are grapes good for diabetics?
Grapes are a low-glycemic food: their glycemic index is 54 (median of 3 lab tests, range 50 to 59). A serving of 1 cup (5.3 oz, 151 g) has 27.3 g of carbs and 1.4 g of fiber, a glycemic load of about 14.
This page is for people with diabetes or prediabetes. The glycemic index compares foods, and the glycemic load on this page adjusts it for a real serving. If you follow a meal plan from your care team, use these numbers within it.
Carbs in a serving
| Per 1 cup (5.3 oz, 151 g) | Amount |
|---|---|
| Total carbohydrate | 27.3 g |
| Fiber | 1.4 g |
| Sugars | 23.4 g |
| Carbs minus fiber | 26 g |
| Glycemic load (GI × carbs minus fiber ÷ 100) | 14 |
USDA FoodData Central, Grapes, red or green (European type, such as Thompson seedless), raw. Glycemic load uses the median GI below.
Glycemic index tests
| Food as tested | GI | Category | Country |
|---|---|---|---|
| Grapes, Crimson seedless | 50 | low | Australia |
| Grapes, green, Menidee, seedless | 54 | low | Australia |
| Grapes, black, Waltham Cross | 59 | medium | Australia |
Glucose = 100. Categories from the International Tables: low 55 or less, medium 56 to 69, high 70 or more. Only tests that met the ISO 26642:2010 method (Supplemental Table 1).
Compared with similar foods
| Food | Portion | GI | Carbs | Glycemic load |
|---|---|---|---|---|
| Grapes | 1 cup (5.3 oz, 151 g) | 54 | 27.3 g | 14 |
| Watermelon | 1 cup, balls (5.4 oz, 154 g) | 50 | 11.6 g | 6 |
| Apple | 1 cup, quartered or chopped (4.4 oz, 125 g) | 44 | 17.3 g | 6 |
| Banana | 1 banana, peeled (4.1 oz, 115 g) | 52 | 26.4 g | 13 |
Same food group in the International Tables, each at its usual US portion (USDA).
How much the glycemic index matters
Studies and guidelines do not agree on how much weight to give the glycemic index.
- 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 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 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 grapes
- Level A Grapes improved one measure of insulin resistance while fasting glucose moved slightly in favor of the control group. Phytother Res, 2021
- Level C In a Chinese cohort of 1,453 pregnant women, those in the top quarter of grape intake in early pregnancy had 35% lower risk of gestational diabetes than those in the bottom quarter. Public Health Nutr, 2021
- Level C In a second Chinese study of 2,987 pregnant women, the amount of grapes eaten in mid-pregnancy was linked to more gestational diabetes, the opposite direction to the cohort above. Clin Nutr ESPEN, 2021
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.
In practice
A cup of table grapes (5.3 oz) has 27.3 g of carbs and only 1.4 g of fiber, and 23.4 g of those carbs are sugar. The three ISO tests, all on table grapes in healthy adults, gave a GI of 50 to 59, and a cup has a glycemic load of about 14.
Grapes are easy to keep eating. Counting out a cup into a bowl, instead of eating from the bag, keeps the load where the numbers on this page put it.
Trials are mixed. A pooled analysis of 29 trials found grapes improved one measure of insulin resistance, while fasting glucose moved slightly in favor of the control group, by about 1 mg/dL.
Evidence behind this note
- Level A Grapes improved one measure of insulin resistance while fasting glucose moved slightly in favor of the control group. Phytother Res, 2021
Written from the agency positions and data on this page, reviewed by the Bioma editorial system. How we verify.
Keep exploring
Sources
- Atkinson FS et al. 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, PMID 34258626, doi:10.1093/ajcn/nqab233 (accessed 2026-10-12)
- USDA FoodData Central, SR Legacy (2018): Grapes, red or green (European type, such as Thompson seedless), raw, FDC ID 174683
- USDA FoodData Central, SR Legacy (2018): Watermelon, raw, FDC ID 167765
- USDA FoodData Central, SR Legacy (2018): Apples, raw, with skin (Includes foods for USDA's Food Distribution Program), FDC ID 171688
- USDA FoodData Central, Foundation Foods (release 2025-12-18): Bananas, ripe and slightly ripe, raw, FDC ID 1105314
- 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.