Applying GI to real-life diets is complex, weigh all information before relying on glycemic index.
If you check different sources on the GI of foods, the numbers don’t always match.
The glycemic index takes into account only the type of carbohydrate, not the amount of carbohydrate, in a usual serving. Some foods are more concentrated sources of carbohydrates than others. For example, chocolate cake has 52 grams of carbohydrate in a usual serving, while carrots deliver only 6 grams of carbohydrate in a serving. So even though the glycemic index of carrots is higher (47, vs. 38 for cake) chocolate cake is going to have a much greater total effect on blood sugar, because it takes 81 servings of carrots to equal the carbohydrate in a serving of cake.
The GI in a given food can vary, depending on where it is grown and how it is processed and cooked. Australian potatoes have a higher GI than American potatoes. In general, the more processed the food, the higher the GI.
Even cooking pasta for a longer time can raise the GI.
Generally, whole grains have a lower GI than refined grains. But glycemic index rankings are often confusing: