The glycemic index, glycemic index, or GI is a measure of the effects of carbohydrates in food on blood sugar levels. It estimates how much each gram of available carbohydrate (total carbohydrate minus fiber) in a food raises a person’s blood glucose level following consumption of the food, relative to consumption of glucose.Glucose has a glycemic index of 100, by definition, and other foods have a lower glycemic index.
| Classification | GI range | Examples |
| Low GI | 55 or less | most fruits and vegetables; legumes/pulses;some whole, intact grains; nuts; tomatoes; fructose;kidney beans; beets; chickpeas |
| Medium GI | 56–69 | whole wheat products, basmati rice, sweet potato,sucrose, baked potatoes |
| High GI | 70 and above | white bread, most white rices, corn flakes,extruded breakfast cereals, glucose, maltose,maltodextrins |
Scientific evidence have shown that individuals who followed a low-GI diet over many years were at a significantly lower risk for developing both type 2 diabetes, coronary heart disease, and age-related macular degeneration than others. High blood glucose levels or repeated glycemic “spikes” following a meal may promote these diseases by increasing systemic glycative stress other oxidative stress to the vasculature and also by the direct increase in insulin levels.
A study from the University of Sydney in Australia suggests that having a breakfast of white bread and sugar-rich cereals, over time, may make a person susceptible to diabetes, heart disease, and even cancer
A study published in the American Journal of Clinical Nutrition found that age-related adult macular degeneration (AMD), which leads to blindness, is 42 percent higher among people with a high-GI diet, and concluded that eating a lower-GI diet would eliminate 20 percent of AMD cases
