Not all carbohydrates are equal! GI is a relative measure of carbohydrates in foods which tells you how they influence your blood sugar levels. GI is a value from 0 to 100 assigned to every food item, with pure sugar benchmarked as 100. Carbohydrates with a low GI value (< 55) cause a slower rise in blood glucose.
In general, carbohydrate-rich foods low in fiber have high GI values. Examples include many sugar-sweetened beverages. By contrast, intact whole grains, legumes, fruits, and vegetables with high fiber content have low GI values.