Diabetes and The Glycemic Index
With many different dietary approaches and guidelines circulating social media, bookstores, and marketing platforms, understanding what is most appropriate for your body can become very confusing. Diets, in general, should never be treated as a one size fits all choice, and it is very important to take into consideration your unique health and medical needs. In fact, a “one-size-fits-all” eating plan is not evident for the prevention or management of diabetes and sets an unrealistic expectation considering the broad spectrum of people affected by diabetes and prediabetes (6).
WHAT IS THE GLYCEMIC INDEX?
Founded in 1981 by two physicians, David Jenkins and Thomas Wolever, the Glycemic Index first focused on plotting curves to show how specific amounts of glucose (sugar) raised blood sugars over a period of two hours time(11). Over time, the Glycemic Index has developed into a system that reviews and compares how specific carbohydrate sources digest and whether they cause a spike or a steady rise in blood sugar(11). This scale follows a 0 to 100 score based on how much carbohydrate source causes blood sugar to rise, and is categorized as follows(11):
- Low-GI Foods: scores of 55 and under
- Medium-GI Foods: scores of 56-69
- High-GI Foods: scores of 70 or higher
If you were to follow a Glycemic Index friendly diet, you would optimize sources that are rated as low (55 and under) to ensure a steady rise in blood sugars without the spike and crash effect caused by some medium and nearly all high scored sources. This type of dietary programming would be extremely beneficial to individuals with precursors to, or a diagnosis of, diabetes.
THE GLYCEMIC INDEX-DIABETES RELATIONSHIP
In the U.S. more than 34 million people have diabetes. This is nearly double the number of cases over the last 20 years as a result of rapid population obesity(3). Now more than ever, Americans need to shift their focus on to more sustainable dietary habits and programming to fight against the increased risk of developing diabetes, or to proactively manage it.
Most of the food we eat is broken down into sugar and released into the bloodstream, as blood sugar rises, the pancreas releases insulin to allow the blood sugars into the body’s cells for energy use(4).
Diabetes is classified as either Type 1 and Type 2(5):
TYPE 1 – The body is unable to produce insulin and breaks down carbohydrates into blood sugar for energy use
TYPE 2 – The body doesn’t use insulin correctly
It is important for prediabetics, or those managing a diagnosis, to understand the Glycemic Index-diabetic relationship. Increasing evidence shows that choosing foods with a low GI has a favorable glycemic response, indicating a slower rate of entry to the bloodstream which reduces insulin response(9). In addition, there is a positive correlation between high-GI food consumption and increases in Type 2 diabetes, supporting that an overall decrease in the glycemic index of one’s diet could improve insulin sensitivity and reduce the risk for diabetes and/or disease(9).
Studies further support findings that the replacement of high-GI foods with low-GI foods improves blood sugar control while reducing hypoglycemic episodes in those with Type 1 diabetes(1).
BENEFITS vs. RISKS
As a nutrition professional, I view the Glycemic Index as a resource and guideline whos benefits outweigh the risks. However, due to the medical complications that can arise with prediabetes and diabetes, it is very important to acknowledge and discuss any potential risks associated with it.
First, it is crucial to consider that the true GI rating of a food can change based on several factors(8):
- Type or variety (i.e. white potato vs. red potato)
- How it is cooked
- How it is stored
It is also important to consider that any individual can experience a different response to a food’s glycemic content. There is a large body of evidence supporting that the following factors influence such responses. Keep in mind that to truly understand the effects of the glycemic content, you would need to check your blood sugar before and after eating(2):
- Changes in sugars after indigestion of equivalent carb exchanges can vary
- Food factors such as final physical and chemical state of the starch
- Viscosity and structural integrity of the source’s fiber
- Nature of the mono and disaccharides present in the carb source
And finally, with regard to the Glycemic Index scoring system, it can be easily misinterpreted as some healthy foods have a very high GI value than some unhealthy foods. Unfortunately, the Index does not specify serving sizes or specific intake amounts such as grams(1).
THE GLYCEMIC INDEX FOOD SOURCES
Here are some examples of low, medium, and high Glycemic Index food sources for reference(10):
LOW (55 or less)
- Fruits – apples, blueberries, peaches, tangerines
- Vegetables – broccoli, avocado, lettuce, mushrooms, spinach
- Grains – barley, rye, wild rice
- Nuts – almonds, peanuts, pecans, sunflower seeds
- Fruits – banana, grapes, kiwi, oranges
- Vegetables – carrots, beets, sweet potatoes, corn
- Grains – cornmeal, brown/white rice, couscous
- Nuts – cashews, macadamia
HIGH (70 or higher)
- Fruits – watermelon, pineapple
- Vegetables – winter squash, parsnips, potatoes (mashed/baked/broiled)
- Grains – instant rice, tapioca rice
- Snacks – candy, crackers, chips, cakes, cookies
Want to learn more about the Glycemic Index? Would you like to discuss how a GI focused nutrition program would benefit your health and wellbeing? Please reach out to me today to set up your free nutrition consultation. I would love to hear from you!