Glycaemic index and how it can help in the management of diabetes

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The standard first line management of type-2 diabetes is diet and lifestyle modification often referred as medical nutrition therapy (MNT) .

As a person with diabetes, one would often wonder about the food items that can one can eat to maintain a healthy blood sugar level.

Most of the guidelines recommend glycaemic index and carbohydrate counting as two of the important methods for diet planning.

In a systematic review published in Diabetes Care, it was found that there is a clear positive association between Glycaemic Index and increasing incidence of type 2 diabetes.[1]

A low GI diet may help you:
  • decrease risk of type 2 diabetes and its complications
  • control blood sugar values
  • decrease risk of heart disease and stroke
  • feel full longer
  • maintain or lose weight
In this article, we will focus on Glycaemic Index and its role in the management of diabetes.

Glycaemic index:

When you consume a food that contains carbohydrates, your body gets down to work by converting them into glucose.

The glycaemic index will rate the carbs according to how quickly they will raise the blood sugar levels.

A low-GI food will cause blood glucose levels to increase more slowly and steadily, which leads to lower postprandial (after meal) blood glucose readings.

Glycemic index (GI) values range from 0 to 100 with pure glucose arbitrarily given the value of 100, which represents the relative rise in the blood glucose level two hours after consuming that food.

A number of factors influence glycemic responses to foods, including the amount of carbohydrate, type of sugar (glucose, fructose, sucrose, lactose), nature of the starch (amylose, amylopectin, resistant starch), cooking and food processing (degree of starch gelantinization, particle size, cellular form), and food form, as well as other food components (fat and natural substances that slow digestion—lectins, phytates, tannins, and starch-protein and starch-lipid combinations)

A related term is GL or Glycaemic Load that will rank carbs according to their GI and the amount of carbs in the said food.

Lets quickly rate carbs according to their Glycaemic Index (GI):

  • Green = Go

Low GI (55 or less) Choose Most Often

  • Yellow = Caution

Medium GI (56 to 69) Choose Less Often

  • Red = Stop and think

Foods in the high GI category can be swapped with foods in the medium and/or low GI category to lower GI.

Example of some food items based upon their glycaemic index (GI):

Meat, poultry and fish do not have a GI because they do not contain carbohydrate.

GI for diabetes and managing your meal:

Remember that checking your blood glucose before and 2 hours after a meal is the best way to know how your body handles the meal.

Also using the Glycemic Index to choose foods is only one part of healthy eating.

Also remember that eating at regular times, choosing a variety of foods from all food groups, limiting sugars and sweets, reducing the amount of fat you eat, including foods high in fibre, limiting salt, alcohol and caffeine is also very important in managing your diabetes well.

[1] Darren et al Diabetes Care 2013 Dec; 36(12): 4166-4171.