Is the Glycemic Index Necessary?
Wojciech Wiśniewski
2026-03-19
4 min. read
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The glycemic index (GI) is a tool that facilitates the selection of food in the diet, especially for individuals with diabetes. The GI can be used to determine how blood glucose levels change after consuming certain foods. How is the GI calculated? On a coordinate system, a curve is presented that reflects the changes in blood glucose levels over time after consuming a product containing 50 grams of available carbohydrates (i.e., carbohydrates minus fiber). Subsequently, the area under this curve is calculated and compared to the area under the curve reflecting blood glucose levels after consuming 50 grams of pure glucose. In this way, for example, a GI value of 50 for sweet corn means that the area under the glycemic curve is half as small as the area of pure glucose.
Glycemic index - its purposes of use
Based on the glycemic index, products are categorized into three groups: high glycemic index (>70), medium glycemic index (56-70), and low glycemic index (55 and below). The lower the glycemic index of a product, the slower the blood glucose level rises after its consumption, which brings many benefits. Knowledge of the glycemic index of products is invaluable for people with diabetes. Prevention of complications from this disease involves controlling blood glucose levels. Monitoring the rise in blood glucose levels can reduce insulin requirements, prevent complications from hyperglycemia, and improve lipid profile. Choosing products with low glycemic index prevents a sudden increase in blood glucose levels, leading to a gentle hormonal response. The sudden release of insulin after consuming easily digestible carbohydrates is also associated with increased lipogenesis in fat tissue. Some studies suggest that a low glycemic index diet can increase the insulin sensitivity of cells. Knowledge of the glycemic index of products or skillful use of tables makes it easier to compose a balanced diet based on products with low and medium glycemic index.
Low- and medium-glycemic index foodstuffs
Foodstuffs with a low to moderate glycemic index should be the primary source of carbohydrates in the diet. As previously mentioned, they are especially important in the diets of people with diabetes. Replacing high-GI items with low-GI ones may contribute to a decrease in glycated hemoglobin levels. Low-GI diets are also recommended for those battling overweight and obesity. They are believed to be effective in reducing body weight, as they provide a longer sense of fullness (they are typically richer in fiber). Further research is required.
When to consume products with a high glycemic index
Foods with a high glycemic index (GI) also have their uses, e.g. in the case of hypoglycemia, i.e. when the glucose level drops below normal. In such a situation it is necessary to raise the blood sugar level immediately, so it is advisable to consume quickly digestible carbohydrates in the form of pure glucose or clear fruit juice. After intense training, when the muscle glycogen stores (glucose stores in the muscles) are depleted and a quick replenishment is required, it is recommended to consume high-GI foods. In this way, glucose is quickly absorbed and used to build glycogen. Foods with a high GI include, for example, mashed potatoes, cornflakes, baguette, white bread, French fries, watermelons, honeydew melons, canned peaches, ripe bananas, gummy bears, and other sweets.
Factors influencing the glycemic index
Our food products have varying glycemic indices, which depend on their fiber content. This fiber is resistant to the action of digestive enzymes in the human body. Beta-glucan is particularly significant, as it is a soluble fiber source. It increases the viscosity of the food content, thereby significantly slowing down the absorption of carbohydrates. Fat also plays a crucial role, as it delays gastric emptying and thus glucose absorption from the intestines. Unsaturated fatty acids can combine with the chains of amylose and amylopectin, forming a complex that impedes the action of beta-amylase. It is recommended to include unsaturated fatty acids in the form of plant oils in the diet, due to their numerous health benefits, including anti-inflammatory effects. Although the glycemic index is not perfect, some studies suggest that a low-IG diet may have positive effects, such as easier blood sugar control, more effective weight loss, and reduction of acne symptoms. We, therefore, recommend trying at least a low-IG diet and individually evaluating its impact on well-being and health.
