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Diabetes and Glycemic Index (GI).

The WHO defined diabetes as: "A chronic disease that occurs when the pancreas does not produce enough insulin or when the body is not able to use the insulin effectively. This results in an increased concentration of glucose in the blood (hyperglycemia). ".

How to calculate this amount of glucose easily through foods we consume every day?

Because of its silent nature and seriousness of complications that it generates, it is considered as a serious pathology in absence of treatment. Two forms of diabetes exist:

• Type 1 diabetes (previously known as insulin-dependent diabetes or juvenile diabetes) is characterized by insufficient insulin production;

• Type 2 diabetes (formerly known as non-insulin-dependent diabetes or adult diabetes) results from inadequate use of insulin by the body. It is also often the result of excess weight and physical inactivity.

My role as a Holistic Nutritionist and Naturopath is essential in my patients’ education to live a better healthy lifestyle with diabetes. It is very important to understand the need to apply simply food hygiene habits to avoid and/or delay any diabetes complications.

Firstly, it is essential to understand the notion of Glycemic Index (GI).

In attempt to quantify the glycemic response induced by different types of carbohydrates, Jenkins introduced in 1981 the concept of the glycemic index (GI).

The GI of various foods were calculated using as reference, the glucose. The GI of a food measures the importance of the change in blood glucose following ingestion of that food. It reflects the speed of digestion and absorption by the body, so the rise in blood sugar following ingestion of this food.

For the same carbohydrate content, not all foods cause the same rise in postprandial glucose.

For example, sucrose (65) has a lower glycemic index than white bread (70) or carrots (71),

starchy foods have very variable glycemic indexes, so pasta and pulses are less hyperglycemic than bread or potatoes.

Numerous studies carried out on this subject have shown that there are significant intra- and inter-individual variations, for instance the way in which the food is prepared, its botanical origin and its use in isolation or in combination with other foods greatly influence glycemic index. Finally, we cannot observe the same glycemic response in a healthy individual and in a diabetic insulin-treated or not.

There are various factors that influence the glycemic response.

- Carbohydrate GI composition of food depends on its composition - simple or complex carbohydrates. Glucose has a high GI (100), sucrose IG (65) and fructose a low GI(23). (Bornet, 1992)

- The speed of gastric emptying. It is not only the rate of carbs hydrolysis that is responsible for the induced glycemic response, but also the speed of gastric emptying. This is one of the parameters that regulates the glucose flow of starchy foods. The control of the gastric evacuation is dependent on the total caloric intake of the ingested meal, the size of food particles in the stomach, and the amount of liquid ingested with solid foods.


Note: you also must take into account the variability of gastric emptying time among individuals. It takes place between 1.15 and 3 hours.

- The structure of the food. Whether mechanical or thermal, manufacturing processes increase the digestibility of starches whose structure is then disorganized (smaller molecules, finer product, solubilization in water). Indeed, the more the structure of the food is aerated, the higher the contact surface with the digestive enzymes, the faster the digestion is of starch. This is the case for bread, crackers, extruded products (breakfast cereals, snacks for appetizers, etc.), cooked potatoes ... For example, you will notice that the GI of the baked potato is 65, while that of potato mashed clay is 80. the higher the potato is transformed => the GI increases. Thus, mashed potato flakes have a higher GI (GI = 90) than home mashed potatoes.

- The least rapidly absorbed carbohydrates are the starches least accessible to amylases. This explains the low glycemic indexes found in dried vegetables, pasta and some pretreated rice varieties.

- The structure of starch. Starchy foods consist of starch particles specific to each species. We meet either linear starches (amylose) or branched starches (amylopectin). A starchy food rich in amylopectin will have a better digestibility and therefore a higher GI.

- Thus, legumes containing 30 to 66% amylose have a lower GI than cereals with an amylose content of 15 to 30%.

- Thermal and mechanical treatments. Cooking modifies the spatial orientation of the starch molecules (destructuring the granule by swelling) and makes them more easily attackable by amylases. So raw pasta has a lower GI than very cooked pasta. The extrusion cooking also increases the GI. We find this type of cooking for biscuits, breakfast cereals.

- Mechanical treatments (masher, blender) modify the physical form of the food, and therefore its bioavailability.

- The presence of fibers. Fibers are grouped into soluble fibers (gums, guar, mucilages) and insoluble fibers (cellulose, lignin). The soluble fibers act by several ways to spread the passage of glucose in the blood, namely: • slowing of gastric emptying; • decrease in digestive enzymatic activity; • transit acceleration; • action on glucagon. Thus, the higher the feed contains fibers, the greater the GI is low. For example, white bread has a GI of 70, while the cereal bread with a GI of 45

- The composition of the meal. At the practical level, it is difficult to study the GI in the healthy subject because the meals are also composed of proteins, lipids, likely to modify the results. These nutrients simply act on the speed of gastric emptying.

To conclude it has been found that a diet rich in low-GI foods has a favorable effect on the reduction of the insulin response postprandial, hence the interest to advise the diabetic patient a diet rich in low GI foods, rich in fiber (whole grains and legumes, vegetable / starch combination with each meal) and focus on the least processed foods possible (al dente cooking, whole and unprocessed foods).

It is also essential to ensure the quality of the meal because, as we have seen, all the nutrients in the meal are related to the carbohydrate response. For that, it will be necessary to eat a varied and balanced diet (as well at the level of the meals as snacks), and rich in fibers.

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