The Glycemic Index and Diabetes

If you think knowing something about the “glycemic index values” of carbohydrate foods might be helpful in managing your blood glucose (glycemic control) you would be correct. But, it’s important to understand the limitations of the glycemic index (GI) where diabetes is concerned – some popular claims may not apply.

You won’t be surprised to learn that some carbohydrate-containing foods digest more quickly than others. Carbohydrate digestion frees glucose previously locked into sugar, starch or fiber compounds. And, the quicker glucose gains its freedom the quicker it gets absorbed into your bloodstream, raising blood glucose levels. When glucose levels begin to rise special cells in your pancreas begin releasing insulin, a hormone which escorts free glucose out of your bloodstream and into storage in muscle, fat and liver cells.

The GI of carbohydrate foods is a measure of how quickly, how high, and for how long blood glucose levels rise in response to eating that particular food after fasting, determined experimentally by measuring the blood glucose response in real people. Foods that raise blood glucose levels quickly and significantly score a value of from 70 to 100 (the GI of glucose is 100), and are called high GI foods. White potatoes, white bread, pretzels and watermelon are high GI foods. Foods with a GI measured at less than 55 are considered low GI foods, and include barley, yogurt, grapefruit, beans, and nonstarchy vegetables.


The confusion may come when we hear claims that low GI foods won’t raiseblood glucose levels, and a calculation called glycemic load often hints that it’s unnecessary to count the carbohydrate. But, the blood glucose response which determines a food’s GI is measured on healthy people, meaning people with a normal response to insulin in bringing blood glucose levels down. By definition, people with type 2 diabetes do not have a normal response to insulin.

There is no downside to adding more low GI foods to your diet – slowly rising blood glucose levels give your body more time to respond to insulin naturally, and most low GI foods are healthy. But, be cautious about looking at the GI and the related glycemic load as an exact science where diabetes is in the picture.

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