There are primarily three types of sugar: glucose, fructose and sucrose. Of the three sugars, fructose is the sweetest and glucose the least sweet, so typically less fructose can be used than table sugar (sucrose) – if sucrose has a sweetness of one, fructose is 1.7 and glucose 0.74. Fructose is known as the fruit sugar as its make source in the diet is fruits and vegetables.