Bananas and diabetes: can you eat them, and how many?
The short answer
Yes, a person with diabetes can eat a banana a day. No fruit is off limits with diabetes. In people with type 2 diabetes, the average glycaemic index of a banana is 48 (average of nine studies), a low GI. It varies with ripeness, from 30 for a still-green banana to about 51 for a fully yellow one. A medium 118 g banana provides 23 g of carbohydrate and a glycaemic load of about 11, which is moderate. The simplest approach: a small banana or half a large one, on the underripe side, with some yoghurt or a few almonds.
This guide gives general guidelines. If you are treated with insulin or with a medicine that can cause hypoglycaemia, your carbohydrate amount per meal should be set with your doctor or dietitian.
What a banana contains
| For | Calories | Carbohydrate | of which sugars | of which starch | Fibre | Potassium |
|---|---|---|---|---|---|---|
| 100 g of banana | 88 kcal | 19.7 g | 15.6 g | 3.8 g | 2.7 g | 320 mg |
| 1 medium banana, 118 g | 103 kcal | 23.2 g | 18.4 g | 4.5 g | 3.2 g | 378 mg |
The Fédération Française des Diabétiques defines a portion of fruit as 15 to 20 g of carbohydrate, roughly what fits in the palm of your hand. A medium banana, with 23 g, is therefore slightly over one portion: a small 100 g banana, with 19.7 g of carbohydrate, or three quarters of a large one, matches it.
Glycaemic index and glycaemic load by ripeness
As it ripens, a banana turns its starch into sugars. A USDA study of supermarket bananas (Phillips et al., 2021) measured about 18 g of fibre per 100 g in green bananas, counting resistant starch, compared with 4 to 5 g in ripe bananas and about 2 g in very ripe ones. Sugars rise sharply between green and ripe bananas, then barely change.
The international glycaemic index tables (Atkinson, Foster-Powell and Brand-Miller, 2008) list measurements made in people with type 2 diabetes, for a 120 g portion:
| Ripeness | Glycaemic index | Available carbohydrate | Glycaemic load | Study |
|---|---|---|---|---|
| Green, underripe | 30 | 21 g | 6 | Denmark, 10 people |
| Yellow with green parts | 42 | 25 g | 11 | United States, 7 people |
| Fully yellow | 51 | 25 g | 13 | United States, 7 people |
| Flecked with brown | 48 | 25 g | 12 | United States, 7 people |
| Very ripe | 52 | 20 g | 11 | Denmark, 10 people |
| Average of 9 studies | 48 | 24 g | 11 | type 2 diabetes |
Two takeaways. First, the big difference is between the green banana and the yellow banana: the Danish study (Hermansen, 1992) found a glycaemic response almost twice as low with the underripe banana as with the very ripe one. Second, between a fully yellow banana and a flecked one, the gap is small, which the USDA sugar analyses confirm.
You will sometimes read that a very ripe banana has a GI of 62 or even 70. Those values exist, but they were measured in people without diabetes, in Canada and South Africa, on bananas whose ripeness was not specified. For a person with diabetes, measurements made in people with diabetes are more relevant. To understand the concept, see our guide to the glycaemic index.
Green banana starch and flour: what the trials tested
Because green bananas are rich in resistant starch, researchers have tested them as a starch or a drink.
- In obese people with type 2 diabetes (Ble-Castillo et al., International Journal of Environmental Research and Public Health, 2010), four weeks of native banana starch led to more weight loss than a soya milk control. Insulin and the insulin resistance index fell compared with baseline, but not significantly compared with the control.
- In 10 healthy women (Zago et al., Plant Foods for Human Nutrition, 2024), adding a cooked green banana pulp drink to a sugary drink lowered blood glucose by 15% two hours later, without changing the digestive hormones measured.
These are small trials using concentrated products. They support the case for a not-too-ripe banana, but they do not justify buying green banana flour supplements.
What about plantain?
Plantain is not eaten as a fruit but as a starchy food. According to Ciqual, cooked plantain contains 28.9 g of carbohydrate per 100 g, nearly one and a half times as much as a dessert banana, and raw plantain has 23.7 g of starch out of 29.6 g of carbohydrate. On the plate, it replaces rice, potatoes or bread rather than being added to them: 100 g of cooked plantain provides almost as much carbohydrate as 200 g of boiled potatoes.
Work out the glycaemic load of your portion
Glycaemic load takes into account the amount eaten: it is the glycaemic index multiplied by the carbohydrate in the portion, divided by 100. Using the Ciqual carbohydrate values and two GIs, underripe (42) and fully ripe (51):
| Portion | Carbohydrate | GL, underripe banana | GL, fully ripe banana |
|---|---|---|---|
| Half a banana, 60 g | 11.8 g | 5 | 6 |
| A small banana, 100 g | 19.7 g | 8 | 10 |
| A medium banana, 118 g | 23.2 g | 10 | 12 |
| A 150 g banana | 29.6 g | 12 | 15 |
How many a day, and when
The Fédération Française des Diabétiques does not set a number of bananas: it advises spreading fruit through the day, for example one in the morning, one as lunchtime dessert and one as an afternoon snack, rather than eating it all at once. One banana a day therefore fits among those fruits, as long as you vary the others.
Should you limit fruit when you have diabetes? A Danish randomised trial (Christensen et al., 2013) followed 63 people at the diagnosis of type 2 diabetes for 12 weeks: one group had to eat at least two pieces of fruit a day, the other at most two. HbA1c fell in both groups, with no difference between them. Restricting fruit brought no measurable benefit.
With protein or fat
Eating the banana with other foods slows stomach emptying and therefore the arrival of glucose in the blood. In practice:
- At the end of a meal, as a dessert, rather than on its own in the middle of the afternoon.
- As a snack, with plain dairy, yoghurt or fromage frais, or with a small handful of almonds or walnuts.
- At breakfast, sliced into porridge made with rolled oats, which provide fibre.
What changes everything: the form
A whole banana does not have the same effect as its derivatives. A smoothie is drunk quickly and fills you up less. Dried banana is a different food: 365 kcal and 47.3 g of sugars per 100 g according to Ciqual, three times as sugary as the fresh fruit, with a portion that disappears in a few bites. As for fruit juice, the Fédération Française des Diabétiques recommends avoiding it, and a large cohort study (Muraki et al., 2013) links it to a higher risk of diabetes, whereas whole fruit is not.
Banana or another fruit: the comparison
The banana is one of the richest fruits in carbohydrate, but its GI remains low. Here are 12 fruits compared per 100 g, with the GI measured in people with diabetes where available:
| 100 g of | Calories | Carbohydrate | Sugars | Glycaemic index | Glycaemic load |
|---|---|---|---|---|---|
| Banana | 88 kcal | 19.7 g | 15.6 g | 48 (9 studies) | 9.5 |
| Grapes | 71 kcal | 16.3 g | 15.4 g | 43 to 49 (2 studies) | 7 to 8 |
| Mango | 71 kcal | 14.3 g | 12.9 g | 41 (1 study) | 5.9 |
| Pear | 57 kcal | 12.3 g | 9.8 g | 38 (4 studies) | 4.7 |
| Pineapple | 52 kcal | 11.7 g | 10.5 g | 51 (1 study) | 6.0 |
| Apple | 54 kcal | 11.6 g | 10.6 g | 36 (5 studies) | 4.2 |
| Kiwi | 61 kcal | 11 g | 8.9 g | 47 (1 study) | 5.2 |
| Plum | 52 kcal | 9.9 g | 9.9 g | 24 to 53 (2 studies) | 2 to 5 |
| Watermelon | 35 kcal | 8.3 g | 7.9 g | 72 to 80* | 6.0 to 6.7 |
| Orange | 42 kcal | 8.0 g | 7.6 g | 45 (5 studies) | 3.6 |
| Peach | 38 kcal | 7.6 g | 6.8 g | 28 to 56 (2 studies) | 2 to 4 |
| Strawberry | 35 kcal | 6.0 g | 5.6 g | 40* | 2.4 |
The case of watermelon shows why the index alone is misleading: its GI is high, but it contains so little carbohydrate that 100 g has a lower glycaemic load than 100 g of banana. Conversely, the banana has a low GI but contains twice as much carbohydrate as an apple or an orange. Pay more attention to the portion than to the index: a small banana equals, in carbohydrate, a large 170 g apple. Our ranking of the least sugary fruits completes this table.
On the prevention side, in the Muraki study of more than 187,000 people followed for up to 24 years, each increment of three servings of banana a week was associated with a slightly lower risk of type 2 diabetes, by 5%. Blueberries, grapes and apples did better; fruit juice did worse, with an 8% higher risk.
Special cases
Gestational diabetes
An Israeli study in women with gestational diabetes measured a GI of 49 for banana, similar to that in people with type 2 diabetes. Banana therefore remains an option, in a small portion and paired with dairy, as part of the spread-out meals recommended by the team following the pregnancy. See also our guide to eating during pregnancy.
Prediabetes
With prediabetes, whole fruit is part of the recommended diet. What matters most is weight loss when needed, physical activity and limiting sugary drinks and juices. The guidelines are in our guide to type 2 diabetes: diet and prevention.
Sport
The banana is a classic snack before or during exercise, as its carbohydrate is easy to carry and digest. For a person with diabetes who exercises, a ripe banana before a long session can help prevent a drop in blood glucose. But to treat a hypoglycaemic episode, it is not the right choice: you need a fast-acting sugar, sugar lumps or juice, according to your care team’s instructions. See what to eat before and after exercise.
Banana or sports drink? A trial in 14 trained cyclists without diabetes (Nieman et al., PLoS One, 2012) compared bananas with a 6% carbohydrate drink, at an equal dose of carbohydrate every 15 minutes over 75 km. Performance and blood glucose were identical. The banana is therefore as effective an exercise fuel as a sports drink, to be dosed with your care team if you are treated with insulin.
Kidney failure
Diabetes can damage the kidneys. With kidney failure, potassium may need to be limited, and a banana contains 378 mg per medium fruit: the amount should be decided with the kidney specialist.
3 suitable snack ideas
- Half a banana and a plain yoghurt: about 12 g of carbohydrate from the banana, and the yoghurt’s protein to slow absorption.
- Porridge made with rolled oats and banana slices: the fibre in the oats accompanies the fruit. See our porridge or our apple and cinnamon overnight oats, to prepare the night before.
- A small banana and a handful of almonds: the fat and fibre in the almonds make a snack that lasts until the next meal. How many to have: see how many almonds a day.
More ideas in our low glycaemic index recipes.
Our banana recipes, in carbohydrate per portion
Values calculated from Ciqual for each ingredient in our recipes:
- Banana and oat cookies: 8.6 g of carbohydrate per cookie. Two cookies equal a small portion of fruit.
- Banana and oat bars with no added sugar: 21.6 g of carbohydrate per bar, more than a portion of fruit despite the absence of added sugar.
- Banana and blueberry smoothie: 27.7 g of carbohydrate per glass, with a yoghurt for protein.
- Banana nice cream: 36.2 g of carbohydrate per serving, one and a half bananas. Half a serving is enough as a dessert.
- Banana protein pancakes: 41.8 g of carbohydrate and 24.8 g of protein per serving. A full breakfast, not a snack.
Frequently asked questions
Can a person with diabetes eat a banana?
Yes. No fruit is off limits. The average GI of a banana in people with type 2 diabetes is 48, a low GI. A small 100 g banana equals one portion of fruit, or 15 to 20 g of carbohydrate.
How many bananas a day with diabetes?
One a day, among the day’s fruit, spread over several moments. Two small bananas on the same day are still possible if they are not eaten together and the other fruit is varied.
Green or ripe banana for someone with diabetes?
The underripe banana: its GI is 30 in the Danish study, against 52 for the very ripe banana, because its starch has not yet turned into sugars.
What is the glycaemic index of a banana?
48 on average in people with type 2 diabetes (nine studies), from 30 for a green banana to about 51 for a fully yellow one. In people without diabetes, measurements range from 47 to 70 depending on the country.
Does a banana raise blood glucose?
Like any food that contains carbohydrate, yes, but moderately: a medium banana has a glycaemic load of about 11. Eaten at the end of a meal or with dairy, the effect is more gradual.
Banana or apple for someone with diabetes?
Weight for weight, an apple contains half as much carbohydrate as a banana, 11.6 g against 19.7 g per 100 g, and its GI is lower, 36 against 48. Both have their place; alternating is the best choice.
Is plantain suitable with diabetes?
Yes, counted as a starchy food: cooked, it provides 28.9 g of carbohydrate per 100 g according to Ciqual. It replaces the rice or potatoes in the meal.
Does green banana flour lower blood glucose?
The trials are too small to say. In obese people with diabetes, banana starch mainly helped with weight loss, with no clear effect on insulin compared with the control.
The foods and diabetes series
Glycaemic index, glycaemic load and the right portion, food by food: apples and diabetes, pears and diabetes, oranges and diabetes, grapes and diabetes, dates and diabetes, melon and diabetes, strawberries and diabetes, pineapple and diabetes, cheese and diabetes, mango and diabetes, honey and diabetes, dark chocolate and diabetes, lentils and diabetes, potatoes and diabetes, avocado and diabetes, rolled oats and diabetes, bread and diabetes, kiwi and diabetes, sweet potato and diabetes, rice and diabetes.
Going further
How many bananas a day, type 2 diabetes: diet and prevention, glycaemic index, least sugary fruits, banana nutrition facts.
Our sources
- Atkinson FS, Foster-Powell K, Brand-Miller JC. International Tables of Glycemic Index and Glycemic Load Values: 2008. Diabetes Care, 2008.
- Hermansen K et al. Influence of ripeness of banana on the blood glucose and insulin response in type 2 diabetic subjects. Diabetic Medicine, 1992.
- Phillips KM et al. Dietary fiber, starch, and sugars in bananas at different stages of ripeness in the retail market. PLoS One, 2021.
- Christensen AS et al. Effect of fruit restriction on glycemic control in patients with type 2 diabetes, a randomized trial. Nutrition Journal, 2013.
- Muraki I et al. Fruit consumption and risk of type 2 diabetes: results from three prospective longitudinal cohort studies. BMJ, 2013.
- Fédération Française des Diabétiques, « Quels fruits choisir en été ? »: fruit portion and spreading through the day.
- Table Ciqual 2025 (Anses): banana, dried banana and raw fruit; USDA FoodData Central, SR Legacy: weight of a medium banana.
- Ble-Castillo JL, Aparicio-Trápala MA, Francisco-Luria MU et al. Effects of native banana starch supplementation on body weight and insulin sensitivity in obese type 2 diabetics. International Journal of Environmental Research and Public Health, 2010. PMID 20623003.
- Zago L, Pessoa HR, Rosado CP et al. Acute Consumption of Cooked Green Banana Pulp Beverage (Musa cavendishii) Decreases Plasma Glucose in Healthy Women. Plant Foods for Human Nutrition, 2024. PMID 38951375.
- Nieman DC, Gillitt ND, Henson DA et al. Bananas as an energy source during exercise: a metabolomics approach. PLoS One, 2012. PMID 22616015.
- Table Ciqual 2025 (Anses): raw and cooked plantain, boiled potato. Recipes on the site: values per portion calculated from Ciqual.
