What is the Glycemic Index and How Do I Use It to Help Manage My Diabetes?
Managing your diabetes can be difficult and stressful, but counting your carbohydrates and using those levels to your advantage to get a leg up on your diabetes can be a huge helping hand! Let us explain what this all means and how to use it to help plan your meals.
Carbohydrate counting is a way to plan your meals so that you are eating less carbohydrates because these raise your blood sugar levels. Carbohydrate counting is easiest when you’re using the glycemic index to it’s fullest potential.
Lets start off with the basics: what exactly is the glycemic index?
Well, the glycemic index (GI) is a scale that ranks carbohydrate-rich foods by how much they raise blood glucose levels compared to a standard food (standard being glucose, or white bread). The purpose of this being that you would eat foods that are less likely to cause large increases of blood sugar levels. High GI foods raise blood glucose faster and higher, where the low GI alternatives raise it slower and lower. Some people can use the glycemic index as a way of diet tracking in order to lose weight, but for this explanation, we’re going to talk about it as a preventative or a way to manage diabetes.
Eating foods with a low glycemic index (low GI) may help to control blood glucose levels, to control cholesterol levels, to control your appetite, to lower your risk of developing heart disease, and may lower your risk of developing type 2 diabetes. In my opinion, that’s a lot of benefits that may be worth it for you to start giving this way of eating a try.
So what is a “low GI” food vs. a “high GI” food?
High GI foods are those that cause an immediate and significant increase in your blood sugars right after eating, where as low GI foods only slightly raise your blood sugars and do it over a longer period of time. It’s the spike of an immediate raise in blood sugars that this diet is trying to prevent. Think of it like that old children’s story, the Tortoise and the Hair. Low GI raises your sugars slow and steady, but high GI sprints right off the starting line. Slow and steady always wins the race.
GI is calculated as a percentage of the value for glucose, so the glycemic index can only be a number out of 100. Low GI is classified as 55 or less, a medium GI can range from 56–69 and high GI is anything 70 or higher.
The GI of a food can fluctuate based on a variety of factors, including how you eat it and what other foods it’s eaten with. So what factors can affect the glycemic index rating?
  1. Types of Starch: amylose vs. amlopectin. Amylose is made from molecules that form tight clumps making the food in question harder to digest. In this case, harder is a good thing! It means that it will digest slowly, causing a lower GI rating. Amylopectin, however, is more processed and refined, leaving the molecules more open and easier for the system to digest. This quick digestion is what spikes the blood sugars, resulting in a higher GI. Refined starches (like white bread) should be avoided as much as possible.
  2. Cooking: cooking foods can increase the GI rating of a given food. Cooking can swell starch molecules, which softens the food, making it faster to digest. Again, fast digestion is what causes the increase in blood sugars. For example: white grain spaghetti when boiled for 5 minutes has a GI rating of 34, but if you boil the same pasta for 10–15 minutes, it increase to a GI rating of around 40.
  3. Food Processing: highly processed foods are digested faster as well. Using white bread as an example again, your typical white bread would have a GI rating of around 73, but unprocessed grains, like pumpernickel, has a GI of 46.
  4. Fat Content: Fat content changes how your body digests foods. Foods with a higher fat content tend to have a lower GI rating. This kind of disproves the idea that low fat foods are the healthier option. Potato chips have a rating of 75 (which isn’t good either), but a baked potato has a super high rating of 93.
  5. Acid Content: acid present in foods slows down the body’s process of digesting that food. Slower digestion means slower rise in glucose levels. Adding vinegar, lemon, pickles, etc. will help to lower the overall GI of a meal.
Of course, using GI is only one part of healthy eating. You should also follow the food guide for choosing your portions and make sure to eat at regular times, limit sugar and sweets, limit alcohol and caffeine, and include many high fibre foods!
According to the Canadian Diabetes Association, here are some examples of foods that fall within the three GI categories.
Examples of low GI options (55 or less):
  • Whole wheat, mixed grain, and pumpernickel breads
  • All bran, bran buds, oat bran cereals
  • Barley, bulgar, pasta/noodles, parboiled or converted rice
  • Sweet potato, lentils, chickpeas, kidney beans, peas, soy beans, baked beans
Examples of medium GI options (56–69):
  • Whole wheat, rye bread and pita bread
  • Puffed wheat cereals, oatmeal, quick oats
  • Basmati rice, brown rice, couscous
  • Potato, corn, popcorn, wheat thins, pea soup, bean soup
Examples of high GI options (70 or more):
  • White bread, bagels
  • Bran flakes, corn flakes, rice crispies
  • short-grain rice
  • Baked potato, french fries, pretzels, rice cakes, soda crackers
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