Fruits That Spike Blood Sugar: GI, Bananas and Portions

Fruit has a mixed reputation when you watch your blood sugar. Some people avoid it. Others eat it freely. So which fruits that spike blood sugar are worth knowing about, and does it matter?

This guide covers GI and GL values, cohort studies, one trial, bananas and UK portion sizes. This guide is general education. If you use insulin or other glucose medicines, follow the plan your diabetes team gave you.

Which are the fruits that spike blood sugar?

Watermelon, cantaloupe, pineapple and cherries have higher glycemic index (GI) values, but GI is only half the picture. Glycemic load (GL) also counts how much carbohydrate you eat.^[6] Watermelon has a GI of 72 to 80 and a GL of only 4 to 5, because a serve holds little carbohydrate.^[2] In USDA FoodData Central, raw watermelon has 7.55 g (0.27 oz) of carbohydrate and 0.4 g (0.01 oz) of fibre per 100 g (3.5 oz), roughly the same as raw strawberries at 7.68 g (0.27 oz) of carbohydrate and 2.0 g (0.07 oz) of fibre, whereas raw grapes have 18.1 g (0.64 oz) of carbohydrate and 0.9 g (0.03 oz) of fibre and raw banana has 22.8 g (0.80 oz) of carbohydrate and 2.6 g (0.09 oz) of fibre per 100 g (3.5 oz).^[7]

Some people call these fruits high in glucose, or high glycemic fruits. Neither is a formal term. GI is the nearest measure. It ranks the blood glucose response to a food against pure glucose, set at 100.^[1][2] The 2021 international tables call fruits usually low-GI foods, meaning 55 or below.^[1] People who search for high glucose fruits usually mean high GI fruits. Fruit sugar is a mix of glucose, fructose and sucrose, so the glucose in a fruit is not the same thing as its GI.^[7]

Think of GI as how fast a food raises glucose, and GL as how big the rise can get in a normal serve. Apple has a GI of 39 and a GL of 6. Pineapple has a GI of 66 and a GL of 6. Pineapple acts faster, yet a serve of each gives a similar glucose load.^[2] That is why sugar levels in fruits are read with GL per serve as well as GI, since GL also counts the carbohydrate in a serve.^[6]

GL is per serve as defined in the tables. A serve is usually 120 g (about 4 oz). Values come from different studies and countries, so read each number as a guide.^[2] Your own readings may differ, and our guide to self-monitoring glucose explains how to check them.

A portion is a size, not a rule. The NHS portion is 80 g (about 3 oz) while the GL figures above assume a 120 g serve (about 4 oz). A bigger bowl brings a bigger glucose load, whatever the GI says.^[5][2]

Do fruits that spike blood sugar need to be avoided?

No. Large studies link whole fruit with slightly fewer new cases of type 2 diabetes, not more. A 2021 review covered 23 cohort studies. In the 20 that looked at fruit alone, the highest intake went with a relative risk of 0.93 (95% CI 0.90 to 0.97) against the lowest.^[8]

An earlier meta-analysis found a relative risk of 0.93 (0.88 to 0.99) per extra daily serving.^[9] These are observational findings in people who did not have diabetes at the start. They show an association. They do not show that fruit protects anyone from diabetes.

A US analysis followed 66,105 women, 85,104 women in a second cohort and 36,173 men. In all, 12,198 developed type 2 diabetes. The table shows the hazard ratio for every three extra servings a week.^[4]

The cohorts were US health professionals with self-reported diet.^[4] A later review noted that most single-fruit findings rest on few studies.^[8]

A trial gives firmer ground. It randomised 63 adults with newly diagnosed type 2 diabetes. They were told to eat at least two pieces of fruit a day or no more than two. After 12 weeks HbA1c had changed in both groups. The gap between them was 0.19% (95% CI -0.23 to 0.62), about 2 mmol/mol, and not significant.^[3]

The authors advised against restricting fruit. The trial was open label, small and short. It is not a promise about your own result.

A trial that asks people to eat more or less fruit tests a habit. It cannot tell you how a slice of watermelon suits you. Your own meter or sensor can, and your diabetes team can help you read the result.^[3]

Which fruits fit a diabetes eating plan?

No single fruit suits everyone, and the evidence does not rank fruits in people with type 2 diabetes. The 2026 American Diabetes Association Standards of Care say whole fruit that is fresh, frozen or canned in its own juice or with no added sugar are all acceptable options.^[6] Diabetes UK adds that having diabetes does not mean you cannot have fruit.^[10]

In the GI table strawberries and oranges had the smallest GL per serve. Apples and wild blueberries sit below 55 for GI.^[2] Blueberries went with fewer new cases in the cohorts. No human berry trial in type 2 diabetes turned up.

Our guide to smart nutrition choices covers wider planning.

Can diabetics eat bananas?

Yes. People with diabetes can eat bananas. The NHS counts one banana as one portion of fruit, and an adult portion is 80 g (about 3 oz).^[5] Banana GI ranges from 47 to 70 across studies, so it is not one fixed number.^[2]

An Australian study gives a GI of 47 and a GL of 11. A Canadian study gives 62 and 16. A South African study gives 70 and 16.^[2]

In the US cohorts, three extra banana servings a week went with a hazard ratio of 0.95 (0.91 to 0.98) for type 2 diabetes.^[4] If you want to know how a banana affects you, check with a meter or sensor and bring the readings to your diabetes team.

Do dried fruit and fruit juice count?

Yes. Both pack more carbohydrate into a small amount. Diabetes UK sets a dried fruit portion at 30 g (about 1 oz), such as 1 heaped tablespoon of raisins or sultanas. A fresh fruit portion is 80 g (about 3 oz).^[10] By weight, seedless raisins pack 79.2 g (2.8 oz) of carbohydrate and 3.7 g (0.13 oz) of fibre per 100 g (3.5 oz) compared with 13.8 g (0.49 oz) of carbohydrate and 2.4 g (0.08 oz) of fibre in raw apple with skin.^[7]

In a trial of 10 healthy adults, dried apricots, raisins and sultanas had GI values of 42, 55 and 51. All sit below white bread at 71. The trial was small, in people without diabetes, and some of its authors declared funding from the dried fruit trade.^[12] Diabetes UK warns it is easy to overdo dried fruit, grapes and tropical fruits.^[13]

For juice the cohort evidence is mixed. A meta-analysis of 14 cohorts found no significant link between overall fruit juice and type 2 diabetes (RR 1.06, 95% CI 0.98 to 1.15). Non-100% juice was linked with higher risk (RR 1.15, 1.03 to 1.28), and 100% juice showed no benefit.^[14]

How much fruit a day with type 2 diabetes?

No guideline reviewed here sets a daily fruit amount for type 2 diabetes alone. The nearest UK guidance is the NHS adult portion of 80 g (about 3 oz), with fruit juice, vegetable juice and smoothies together kept to 150 mL (about 5 fl oz) a day.^[5]

The trial above split people at two pieces a day and found no HbA1c difference.^[3] Ask your dietitian how fruit fits your plan. This matters most if you use insulin or other medicines that can cause low blood sugar.

1. Choose whole fruit that is fresh, frozen or canned in its own juice with no added sugar.^[6]
2. Use an 80 g (about 3 oz) portion for fresh fruit and a 30 g (about 1 oz) portion for dried fruit as a practical starting point.^[5][10]
3. Swap fruit juice for water or whole fruit, or keep juice and smoothies combined to no more than 150 mL (about 5 fl oz) a day.^[5][6][13]
4. Pair higher-GI or higher-carb fruit such as banana or grapes with protein or fat, such as plain Greek yogurt or nuts, and check your meter two hours after eating.^[2][11]
5. Talk to your diabetes team or dietitian before changing your fruit or carbohydrate intake if you use insulin or a sulfonylurea.^[6][15]

If you use insulin or a sulfonylurea such as gliclazide or glimepiride, changing how much fruit or carbohydrate you eat can shift your readings and raise the risk of a hypo unless your medicine plan is reviewed.^[15] Low blood sugar usually means below 4 mmol/L (72 mg/dL) in the UK or below 70 mg/dL (3.9 mmol/L) in the US.^[15][16] Our guide to low blood sugar lists the warning signs. In the UK, the NHS says to call 999 if someone may have very low blood sugar and is not responding normally or is unconscious, and a glucagon injection is not available or you do not know how to use it, or they have not recovered within 10 minutes of a glucagon injection, or they have been drinking alcohol.^[15] In the US, the ADA says to call 911 right away if someone is unconscious and glucagon is not available or no one knows how to use it.^[16]

Questions to ask your diabetes team

• How many portions of whole fruit fit my daily meal plan and glucose targets?^[3][5][6]
• If I change how much fruit or fruit juice I have, do any of my insulin or tablet doses need to be adjusted?^[6][15]
• What post-meal blood glucose range should I aim for two hours after eating fruit?^[11]
• Can you refer me to a registered dietitian to help me plan snacks and portions?^[6]

Frequently asked questions

Which fruits spike blood sugar the most?

Watermelon (72 to 80), cantaloupe (65 to 70), pineapple (66) and dark cherries (63) sit above the low-GI threshold of 55.^[2][1]

Should people with type 2 diabetes avoid fruit?

Not on current evidence. In a 12-week trial of 63 adults with newly diagnosed type 2 diabetes, HbA1c did not differ between high-fruit and low-fruit advice. Ask your diabetes team about your own plan.^[3]

Is fruit juice as good as whole fruit?

No. Diabetes UK says juice and smoothies have most of the fibre removed and limits juice to one small 150 mL (about 5 fl oz) glass a day. The ADA advises replacing any juices with water or no-calorie drinks.^[13][6]

Is a banana a high-GI fruit?

It depends on the study. Tables list banana GI as 47 in Australia, 62 in Canada and 70 in South Africa, with a GL of 11 to 16. That straddles the threshold of 55.^[2][1]

What is the sugar level in fruits?

It varies a lot. Per 100 g (3.5 oz), raw watermelon has 7.55 g (0.27 oz) of carbohydrate and raw strawberries 7.68 g (0.27 oz). Raw grapes have 18.1 g (0.64 oz) and raw banana 22.8 g (0.80 oz).^[7]

Where to go next

For more on checking your own response to meals and planning balanced portions, see:

• Know your numbers, to see how a food affects your own readings.
• Smart nutrition choices, for how fruit fits into a whole day of eating.
• Is Diabec legit?, for what is in our supplement and what it does not do.

Note: If you are pregnant, breastfeeding, or considering giving any supplement or herbal product to a child, consult your healthcare provider before making any changes to your diet, supplement routine, or prescribed medications.

Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Talk to your doctor before changing your diet, your activity or your medicines, and before starting any supplement.