how much sugar does a banana have
exists and is an alternate of . In a medium sized banana which is usually around 126g, there is at least 21g of sugar. In a medium sized banana which is usually around 126g, there is at least 21g of sugar. Bananas raise are high enough in sugar and starch to contribute to high glucose levelsâ¦, especially since they are often consumed without other fats and proteins, which could at least slow the absorption of glucose. Not good.