Fruits are a good source of fibre and essential vitamins we need for health. But they also contain sugar that can raise blood sugar levels. Does this mean you should avoid fruit if you have prediabetes or type 2 diabetes?
Let’s find out!
What is prediabetes?
Prediabetes means your blood sugar is higher than usual but not high enough to be in the diabetes range. It develops for different reasons, including your ethnic background, family history, weight, the quality of your diet and activity levels.
You can’t do anything about your ethnicity and family history, but you can change your weight (if overweight or obese), improve your diet quality and increase your activity levels to reduce your risk of diabetes and manage your blood sugar levels.
Research shows that carbohydrates, including grains, tubers and fruit, have the greatest impact on blood sugar levels. Some people with prediabetes and type 2 diabetes choose to eliminate them from their diet, but we know this is unnecessary, especially because fruits contain compounds that can lower blood sugar.
The health benefits of fruits
Fruits provide vitamins, including vitamins B2, B6 and C, and minerals, such as magnesium, zinc, potassium and phosphorus; studies show that magnesium improves insulin sensitivity and regulates blood sugar. Fruits also supply antioxidants that fight inflammation and infections, reducing the risk of cancers, diabetes, heart disease and depression.
Whole fruits are a good source of soluble fibre, especially pectin. Research shows that pectin slows digestion and reduces the speed at which glucose enters the blood. It also helps people to stay full for longer, promotes weight loss and acts as a prebiotic that feeds probiotic or ‘good’ bacteria, allowing them to flourish and maintain gut health.
How fruits affect blood sugar
Fruits contain carbohydrates, so they can raise blood sugar. However, because they contain soluble fibre that slows digestion, most fruits raise blood sugar slowly to moderately. This means that fruits generally have a low-medium glycaemic index (GI).
Temperate climate fruits like apples, pears, peaches, plums, and grapefruit generally have a low GI value. In contrast, tropical fruits, such as pineapple, banana, mangos and watermelon, have higher GIs. However, this doesn’t mean you should avoid tropical fruits; you can eat all fruits in moderation.
The Glycaemic Index of Common Fruits (per 50g portion)
| Fruit | Glycaemic Index |
| Apple | 44 |
| Apricot | 34 |
| Banana | 57 |
| Blueberries | 53 |
| Cherries | 41 |
| Dates | 54 |
| Figs, dried | 61 |
| Guava | 29 |
| Grapes | 54 |
| Grapefruit | 47 |
| Kiwi | 53 |
| Lychee | 57 |
| Mandarin | 52 |
| Mango | 51 |
| Orange | 42 |
| Papaya (Pawpaw) | 56 |
| Peach | 42 |
| Pear | 38 |
| Persimmon | 61 |
| Pineapple | 82 |
| Plum | 39 |
| Prunes, pitted | 40 |
| Raisins | 49-61 |
| Strawberries | 40 |
| Sultanas | 56 |
| Watermelon, red-fleshed | 48 |
How to eat fruits to prevent blood sugar spikes
Although fruits have a low-medium GI, eating large amounts in one sitting can cause blood sugar spikes. It is best to eat one portion of fruit at a time or a portion that provides roughly 15g of carbohydrates (see the table below).
The best types of fruits to choose from are fresh, frozen or tinned fruit in its natural juice. Avoid tinned fruit with syrup or added sugar. For better blood sugar control, pair fruit with foods containing protein and healthy fats, such as nuts, seeds, nut butter, hummus, cheese or plain Greek yoghurt.
What counts as a portion of fruit?
| Fruit size | Quantity |
| Small, fresh | 2 plums, 2 satsumas, 1 large kiwi, 2 nectarines, 2 small oranges, 1 African star apple (agbalumo), 2 small guava, ¾ cup berries, 12 cherries, 17 grapes |
| Medium, fresh | 1 apple, 1 pear, ½ banana, 1 soursop (graviola, guanabana). |
| Large, fresh | ½ grapefruit, 1 small slice papaya, 2 small slices mango. |
| Dried fruit | 30g or 2 tablespoons raisins, sultanas, prunes, dates, and currants. |
What about fruit juices and smoothies?
Your body absorbs the carbohydrates from fruit juice and some smoothies more quickly than the carbohydrate from a serving of whole fruit. Depending on how you make them, smoothies are better than fruit juice because they still retain fibre, which slows digestion.
Tips
Avoid drinking more than a small glass or 150ml of juice in one sitting, and always drink your juice with your main meal. Also, avoid making smoothies with fruits only and adding sugar or syrups. Instead, consider adding avocados or leafy vegetables like spinach or kale to boost fibre and protein-rich foods like yoghurt, milk, or silken tofu to your smoothies. Vegetable and protein-rich foods will slow digestion, make you feel full and prevent blood sugar spikes.
The Takeaway
- Fruits are a fantastic source of antioxidants that boost health; you don’t need to cut them from your diet if you have prediabetes or type 2 diabetes.
- Aim for two servings of fruit daily and eat one portion at a time.
- Pair fruit with foods containing protein and fat for better blood sugar control.
REFERENCES
- Cosme, F., Pinto, T., Aires, A., Morais, M.C., Bacelar, E., Anjos, R., Ferreira-Cardoso, J., Oliveira, I., Vilela, A., & Goncalves, B. (2022) Red fruits composition and their health benefits – a review. Foods, 11(5): 644.
- Lv, X., Zhao, S., Ning, Z., Zeng, H., Shu, Y., Tao, Q., Xia, C., Lu, C & Liu, Y. (2015) Citrus fruits as a treasure trove of active metabolites that potentially provide benefits for human health. BMC Chemistry, 9: 68.
- Dreher, M.L. (2018) Whole fruits and fruit fibre emerging health benefits. Nutrients, 10, 1833.
- Al Alawi, A.M., Majoni, S.W., & Falhammar, H. (2018) Magnesium and human health: perspectives and research directions. International Journal of Endocrinology, doi: 10.1155/2018/94041694.
DISCLAIMER: Not a substitute for medical advice – All content is for informational purposes only and is not intended to provide medical or nutrition advice or to take the place of medical/nutrition advice or treatment from your doctor or health professional. Since each person’s health conditions are very specific, viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. All content, including text, graphics, images, and information in this post/video, is for general information only and does not replace a consultation with your doctor/health professional.
