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glycemic index and diabetes

Understanding Glycemic Index and Diabetes Connection


The glycemic index and diabetes connection affects those with the disease and those at risk. Diabetes disease occurs when your body is unable to utilize the glucose (or sugar) in your blood properly. As a result, your blood glucose level becomes higher than normal. This usually leads to serious complications.

The type of food you eat can determine how fast your blood glucose rises.  Carbohydrate foods like bread or refined sugars convert more easily into glucose for your energy needs, than other slowly digested carbohydrate-containing foods like whole grains or vegetables.  Eating these easily converted carbohydrates makes harder to control your blood sugar level.

What is Glycemic Index?

glycemic index and diabetesThe glycemic index (GI) is a number ascribed to foods to indicate the effect of the individual food on a person’s blood glucose (sugar) level.  A standard value of 100 represents pure glucose.

The glycemic index provides an idea of how fast your body can convert your food carbohydrate into glucose. The higher the number, the more impact the food has on your blood sugar. Likewise, a lower number represents less impact. Generally, a value of  55 or less represents Low (good) carbohydrate in this context; while 56 – 69 is medium and 70 or higher is high (bad).

You can find the glycemic index on the labels of some packaged foods. Also, a list of the glycemic index of common foods exists on this pdf.

Factors Affecting the GI of a Food

A number of factors actually affect the GI of the food you consumed. For instance, the amount of carbohydrate in the food you consume ultimately determines how much glucose becomes available in your blood at a time. This factor calculated by another measurement known as Glycemic Load (GL).  To calculate GL, multiply the Glycemic Index (GI) of any particular food by the carbohydrate amount or content of the consumed food. For example, while watermelon which has a high glycemic index will have a low glycemic load when consumed moderately; fructose, on the other hand, which has a low glycemic index, will have a high glycemic load if consumed in large quantity.


Easy Breakfast Ideas for Diabetics


The following are some examples of factors that can specifically affect the GI of a food:

  • Natural state or processed.
      • Generally, the more processed or cooked a food is, the higher the GI.


  • Ripeness
    • The more a fruit or vegetable ripens, the higher the GI becomes.
  • Fat and fiber
    • Fat and fiber tend to lower the GI of a food. The glycemic index represents only the amount of carbohydrate available (total carbohydrate minus the fiber) in a food. According to Dr. Howard, an American Heart Association (AHA) volunteer, “it’s very clear that if a certain amount of fat is ingested, it will retard the absorption of sugar no matter what the glycemic index is.”


  • Processing
    • affects the GI of foods. For example, whole wheat bread has a higher GI than stone ground whole wheat bread; whole fruit has a lower GI than commercial juice; a whole baked potato has a lower GI than mashed potato.
  • Cooking method
    • the extent of cooking of a food affects its GI. Soft-cooked pasta has a higher GI than al dente pasta.
  •  Variety
  •  brown rice has a lower GI than short-grain white rice but a higher GI than converted long-grain white rice.


  • Combinations
    •  Two or more different foods combined together and consumed will have a different GI from each of the foods consumed alone. The GI of a food is different when eaten alone than it is when combined with other foods. You can combine a high GI food with other low GI foods to have a better effect on the blood glucose level.
  • Nutritional Value
    • Food with little nutritional value has a lower GI than many nutritious foods. For example, Chocolate has a lower GI than oatmeal. Basic nutritional principles of variety have to be considered along with the use of the GI to ensure healthful foods as well as moderation of foods with few nutrients. The glycemic index shouldn’t be the only consideration when you are making choices on what to eat. Low glycemic index foods are not necessarily the best on their own. There is the need for vitamins, minerals, and calories. For example, oatmeal and green peas have more nutrients than potato chips although the latter has a lower glycemic index than oatmeal and about the same GI as green peas.

Making the connection: Glycemic Index and Diabetes

The glycemic load will help you to accommodate both the quality and the quantity of your carbohydrate at the same time. A less than 10 glycemic load is low, while a more than 20 is high. You can still healthily consume foods with a high glycemic index by doing so in smaller portions while balancing them with nutritious, low GI foods.

Studies have revealed that the total amount of carbohydrate in food is generally a stronger determinant of blood glucose response than the GI.  Research has also shown that carbohydrate counting is the first tool for managing blood glucose for most people with diabetes.

Due to the fact that the type of carbohydrate can affect blood glucose level, the use of GI may be helpful and can enhance blood glucose management. That means that GI in combination with carbohydrate counting may be of additional benefit in achieving blood glucose goals for those who want to and can put extra effort into monitoring their choices of food consumption.

You need a balanced diet

The American Heart Association (AHA ) advises that diabetes glycemic index should be used as a means of choosing a healthy carbohydrate. However, this should be used in conjunction with other considerations like nutrition, in planning the diet of diabetics.  Dr. Howard stated that the healthful benefits of complex carbohydrates like whole grains stem from the nutrient content of the food, rather than the glycemic index.  Furthermore, the fact that a food has high glycemic index does not mean it is not beneficial to you. For instance, “fruits tend to have higher glycemic indices, but they’re also good for you and a great to eat for a snack,” as stated by Dr. Howard. However, Dr. Howard cautioned that “just because something is high glycemic, doesn’t mean you can eat as much of it as you want.” Consequently, managing the issue of glycemic index for diabetics might require the help of your physician or dietician.

Glycemic Index and Diabetes: Weight control

Overweight or obese people constitute about 90% of people with type 2 diabetes. Such people have impaired the ability to make use insulin to adequately control their blood sugar levels. Therefore, they are more likely prone to developing diabetes.

In achieving quick weight loss, saturated fat foods can be replaced by low glycemic index carbohydrate and it is quite desirable; but this is not true of refined, high glycemic index carbohydrate.[1] A Cochrane review has revealed that overweight or obese people can achieve more weight loss and better control of fat by adopting low glycemic foods than by using higher glycemic index/load diets or other strategies.[2] The benefits were even apparent with low glycemic index/load diets where people eat as much as they want.[2] The review authors  concluded that “Lowering the glycemic load of the diet appears to be an effective method of promoting weight loss and improving lipid profiles and can be simply incorporated into a person’s lifestyle.”[2]

Diets based on a low glycemic index/load appear to provide better glycemic and inflammatory control than high glycemic index/load ones. They are therefore possibly more potentially effective in preventing obesity-related diseases.[3]

Glycemic Index and Diabetes: Disease Prevention

Scientific evidence has shown that individuals who adopted a low-GI diet over many years have a significantly lower risk of developing type 2 diabetes, coronary heart disease, and age-related macular degeneration than others.[4] These diseases are promoted by high blood glucose levels or repeated glycemic “spikes” after a meal consumption and also by the direct insulin level increase.[5]

Hyperglycemia following food consumption is also a diabetes-associated risk factor. There is remote evidence to show that it also presents an increased risk for atherosclerosis in the non-diabetic population.[6] Furthermore,  high GI diets, high blood-sugar levels more generally, as well as diabetes[7] are also associated with kidney disease.

Conversely, there are places like in Asia and Peru where people eat high-glycemic index foods such as potatoes and high-GI rice and still have a low level of diabetes or obesity. The high consumption of legumes in South America and fresh fruit and vegetables in Asia is likely responsible for the lowers glycemic effect in individuals from these areas. The mixture of low- and high-GI carbohydrates results in moderate GI values.

A food with a high glycemic index can have a low carbohydrate content or vice versa; this can be taken care of with the glycemic load (GL) where GL= GI% x grams of carbohydrate per serving. Carbohydrate diets with a low glycemic index and calculated carbohydrate intake would result in a stable blood sugar level.


vegan diet for diabetes


  1. Brand-Miller J, Buyken AE (2012). “The glycemic index issue”. Curr. Opin. Lipidol. 23 (1): 62–7. PMID 22157060. doi:10.1097/MOL.0b013e32834ec705.
  2. Thomas DE, Elliott EJ, Baur L (2007). “Low glycemic index or low glycemic load diets for overweight and obesity”. Cochrane Database Syst Rev (3): CD005105. PMID 17636786. doi:10.1002/14651858.CD005105.pub2
  3. Schwingshackl L, Hoffmann G (2013). “Long-term effects of low glycemic index/load vs. high glycemic index/load diets on parameters of obesity and obesity-associated risks: a systematic review and meta-analysis”. Nutr Metab Cardiovasc Dis. 23 (8): 699–706. PMID 23786819. doi:10.1016/j.numecd.2013.04.008.
  4. Chiu CJ, Liu S, Willett WC, et al. (April 2011). “Informing food choices and health outcomes by use of the dietary glycemic index”. Nutr. Rev. 69 (4): 231–42. PMC 3070918 Freely accessible. PMID 21457267. doi:10.1111/j.1753-4887.2011.00382.x.
  5. Temelkova-Kurktschiev TS, Koehler C, Henkel E, Leonhardt W, Fuecker K, Hanefeld M (December 2000). “Postchallenge plasma glucose and glycemic spikes are more strongly associated with atherosclerosis than fasting glucose or HbA1c level”. Diabetes Care. 23 (12): 1830–4. PMID 11128361. doi:10.2337/diacare.23.12.1830
  6. Balkau B, Shipley M, Jarrett RJ, et al. (March 1998). “High blood glucose concentration is a risk factor for mortality in middle-aged nondiabetic men. 20-year follow-up in the Whitehall Study, the Paris Prospective Study, and the Helsinki Policemen Study”. Diabetes Care. 21 (3): 360–7. PMID 9540016. doi:10.2337/diacare.21.3.360.

7 “Diabetes and kidney failure”. Better Health Channel. State Government of Victoria. Retrieved 2012-02-21.