Watermelon Sorbet -- Watermelon and Glycemic Index -- Although it has a high Glycemic Index (GI = 72), it has a very low Glycemic Load (GL = 4). GL, which measures how much insulin will be released by your body for a given food measured in standard portions. This is different to GI, which doesn't take the serving size into account. As a result, some foods with high GI could have low GL. Therefore, GL is recommended as the best measure for carbs.