Carbohydrates are classified on the basis of their physiological effect as glycemic and non-glycemic. Glycemic carbohydrates are those that have an effect on blood glucose levels. According to the American Diabetic Association, the glycemic index (GI) measures how a carbohydrate-containing food raises the blood sugar level. Glycemic index is a relative indicator of blood glucose response to the carbohydrate present in the foods. Some carbohydrates break down faster than other and the glucose that is obtained upon digestion is absorbed rapidly into the bloodstream, raining blood sugar quickly. Such carbohydrates are said to have a high GI, eg. Foods such as rice, sugars; such as sucrose and glucose etc. In comparison, there are carbohydrates that break down relatively slowly, hence the glucose is released more gradually into the bloodstream and blood sugar levels will not be raised very quickly. Such foods and carbohydrates are said to have a low glycemic index.
Although GI does not indicate the carbohydrate content of the food or the type of carbohydrate, it signifies the physiological impact of the carbohydrate. Therefore, it is helpful in meal planning for people having diabetes, insulin resistance, hyperlipidemia, polycystic ovary syndrome (PCOS) and weight problem. The Glycemic index is useful for the dietary management of diabetes mellitus.
The highest possible GI is 100 indicating that the test food will raise blood sugar to the same extent that the reference food or glucose do. Foods categorized into three groups as follows:
Low Glycemic foods are those with a glycemic index of 55 or less. Examples are non-starchy fruits, whole unprocessed unrefined grains, pulses, vegetables. Foods rich in fiber generally have low gycemic index .e.g. Green leafy vegetables, whole pulses, beans, sweet potato, fruits like papaya, apple, pear, orange, milk, pasta, bulgur, wheat.
Medium Glycemic foods are those with gycemic between 56 and 69 e.g. brown rice, basmati rice
High glycemic foods are usually foods with a glycemic of >70%. These foods show a higher potential for rapid rise in blood sugar. With the consumption of high glycemic foods for a prolonged period, more insulin is frequently produced to manage the intake and cells receptors are frequently bombarded and eventually, the insulin secretion or the sensitivity of the insulin receptors of the cells are either insensitive or dysfunctional, leading to insulin resistance and diabetes. High glycemic foods contain large amounts if starches that are easily digested, e.g. potato, rice, refined cereals like white bread, large amounts of disaccharides that will be rapidly broken down into glucose, all candies, confectionery, bakery, fruit juice.