Diabetes and eating by the Glycemic Index

Sep 28, 2007 at 9:29 p.m. ET

The Glycemic Index (GI) can help lower blood sugar levels and keep them steady throughout the day. This means no heavy-duty bingeing or out of control snacking at the end of the day.

Why GI?
The glycemic index indicates the after-meal response your body has to a particular food compared to a standard amount of glucose, according to the Joslin Diabetes Center in Boston.

In layman's terms, it's basically how quickly what you have eaten turns to sugar and how high your sugars go up.

In general, fiber-rich foods are often the same foods that are thought to be low-glycemic foods and seem to have less effect on blood sugars, according to Joslin. Unbelievable but true, table sugar has a lower glycemic index than such starches as potatoes.

The glycemic index is a measurement of the effect a food has on one's blood sugar level. Some foods, which have a high amount of sugar in them such as, maple syrup, honey and candy, as well as starchy foods like carrots, potatoes and some cereals, are rated high on the glycemic index.

They are rated this way because when you eat these foods you will experience a rapid rise in your blood sugar level, says Joanne Larson, MS, a registered dietitian. Other foods, especially those high in fiber, are rated low on the GI because they do not produce a rapid rise in blood sugar after eating them, she explains.

"It is important to understand that high-GI products are not unhealthy and do not have to be avoided. However, the evidence is pointing to the reality that overall lower GI-diets are to be preferred, says Jennie Brand-Miller, co-author of The New Glucose Revolution.

Studies bear this out and indicate that consumption of low-glycemic index foods could be key to both prevention and management of diabetes. "The studies are quite clear -- in people with type 1 diabetes, children and adults, and people with type 2 diabetes, short to medium term consumption of a low-GI diet improves diabetes control," says Dr Stephen Colagiuri of the Diabetes Center at Prince of Wales Hospital in Sydney, Australia and co-author of The New Glucose Revolution. "With respect to prevention of type 2 diabetes, there appears to be a significant link between dietary glycemic load (i.e., GI plus carbohydrate intake) and the development of diabetes."

Counting carbohydrates versus the Glycemic Index
According to Joslin, most dietitians and other healthcare professionals refer to the number of carbohydrate grams in a food, rather than the food's GI. There are a number of reasons for this.

Joslin contends that GI is a complex meal planning tool, and the fact that people's blood sugars can react differently to so-called "low" and "high" glycemic index foods has limited the usefulness of the index in teaching patients with diabetes how to manage their food intake to keep their blood sugars under control.

Further, carbohydrates have the greatest effect on blood sugar, so in general two foods that have the same number of grams of carbohydrate will have a similar effect on blood sugar level.

A dietitian can work with you to determine, based on your weight, how active you are and other factors, how many grams of carbohydrates you can eat at each meal and snack to keep your blood sugars under control.

This type of meal planning is easier to use, offers greater flexibility and enables many people to manage their diabetes successfully, Joslin concludes. According to Joslin, many health professionals agree that the more complex a meal plan, the less likely people will follow it. However, the glycemic index may be used in tandem with a carb-counting program or other meal planning system.

Registered dietitians often encourage patients to determine their own individual GI of foods based on how their blood sugar responds to the various meals and snacks they tend to eat, Joslin reports.

Here are some examples of foods and where they sit on the glycemic index:

Yogurt, low-fat, fruit, with aspartame 14
Yogurt, low-fat, fruit, with sugar 33
Apricot fruit spread, reduced sugar 55

White rice, type not specified, boiled 45
Apple, oat muffin, made from packet mix 54
Oat bran 50
Oatmeal made from raw rolled oats 75

Water crackers, plain 78
Soda crackers 74
Rice cracker, plain 91

Baked Beans, canned 56
Blackeyed beans/peas (Cowpeas), boiled 50
Chickpeas (Garbanzo beans), dried, boiled 36
Haricot/Navy beans, boiled 39

Low Glycemic Index food (less than 55)
Foods with GI index between 55 and 70 are considered intermediate
High Glycemic Index food GI (more than 70)

For more information, visit The University of Sydney's Glycemic Index Database. Click on GI database at the left and add a food of your choice to look up.