Although many people know about exchange lists (foods grouped by similar
nutrients) and carbohydrate counting as useful ways to plan their meals
and help control blood sugar, many more are asking questions about a relatively
new (and still controversial) concept called the glycemic index.
The glycemic index , developed in 1981 by. Dr. David Jenkins, a nutrition
professor at the University of Toronto , distinguishes between types of
carbohydrates and measures how quickly they become glucose in the body.
He looked at the speed at which different foods affect blood glucose levels
and compared the numbers to a slice of white bread. White bread is given
the glycemic index value of 100. Foods that have a value less the 100
are converted into sugar more slowly than white bread. Foods that have
a glycemic value greater than 100 turn into sugar more quickly than white
bread (1). Looking at the table below may surprise you.
Foods such as milk and fruit tend to have a lower glycemic index value
than common starchy foods such as bread, rice, potatoes and some breakfast
cereals. Even table sugar (sucrose) has a glycemic index of 83, slower
than some starchy foods.
Selecting foods with a low glycemic index value may help you to manage
your diabetes. Increasing the number of low glycemic foods such as legumes,
barley, pasta and whole grains in your diet may have real benefit in controlling
blood sugar levels (2). Most low glycemic index foods are higher in fibre
and low in fat, something dietitians have been advocating for years. Il
is important to remember that while table sugar may produce a slower rise
in blood sugar than potatoes it also lacks the vitamins, minerals and
fibre provided by the potato. Decisions on food choices must be made on
overall nutrition as well as the impact on blood sugar.
Where I think using the index shows interesting promise is in helping
to regulate blood sugars during exercise. Faster carbohydates (higher
numbers) could be used for raising low blood sugars and for covering brief
periods of intense exercise. Slower carbohydrates (lower numbers) could
be used before long periods of exercise as well as after to help prevent
delayed onset hypoglycemia.
However it may not be as easy as it sounds. The actual glycemic (blood
sugar) impact of a given food depends not just on its glycemic index value
but on preparation method and cooking time, the amount eaten, and what
other foods are eaten at the same time (such as proteins and fats). It
is important to remember that glycemic index tables are an average of
the glycemic response of many individuals. For this reason I usually recommend
the table be used as a starting place and that with regular self monitoring
of blood glucose and good note taking you can develop your own personal
Here are some suggestions on how to how to get started.
- Eat whole grain, pumpernickel and oat bran bread more often than white
- Eat pasta, sweet potato or beans more often than mashed or instant
- Experiment with using foods such as rice cakes, corn flakes or white
bread and jam for snacks prior to a short, intense workout.
- iSee if snacking on fruits, milk or yogurt, or whole grain breads
help to sustain your blood sugars through longer exercise periods. Try
them as after exercise snacks as well.
Good luck and I'd love to hear about your experiences.
- Whitham, D. and Hamilton, T. (2000). The Index in Depth.
- Diabetes Dialogue. Spring 2000. Canadian Diabetes Association.
- Wolever, TMS. (1997). The glycemic index : flogging a dead horse
? Diabetes Care.; 20. 452 - 456.
Additional Reading :
·Powell, K.F. and Miller, J.B. (1995). International tables of
glycemic index. American Jounal of Clinical Nutrition, 62, 871S - 93S.
Carbohydrates in human nutrition. Report of a Joint FAO/WHO Expert Consultation,
Rome, 14 - 18 April, 1997, FAO Food and Nutrition Paper 66. Rome 1998.