October 3, 2007

Study: The So-Called Glycemic Index is Nonsense for Type 2s!

Diabetes In Control points today to a study published in Diabetes Care that proves what I've been saying for years.

The Glycemic Index is meaningless for people With Type 2 Diabetes.

Interindividual Variability and Intra-Individual Reproducibility of Glycemic Index Values for Commercial White Bread

The glycemic index is a measure of the impact a food has on blood sugar. The study found that while the average glycemic index of white bread was 71, in the individuals who participated in the study the actual glycemic response could be anything from 44 to 132. In short, it was meaningless.

This is no surprise. As I wrote in an earlier blog entry, The "glycemic index" is meaningless for people with diabetes because all that supposedly "high glycemic" foods do is slow down the digestion of the carbohydrates they contain.

If you have enough phase two insulin to mop up carbs 2 or 3 hours after eating, a slower digesting high carb food will be a bit better for your blood sugar. But most people with longstanding Type 2 diabetes have little or no second phase insulin. So it doesn't matter how long it takes a food to digest. Every gram of carb they eat will hit their blood sugar and raise it. For them, it doesn't matter if they're eating Oatmeal or drinking regular Pepsi, 50 grams of carbs in either form will push up their blood sugar to damaging levels.

If you don't understand what "second phase insulin response" is, read this page: How Blood Sugar Control Deteriorates. It will explain a lot of things your doctor forgot to mention--or doesn't know.

Because there is so much individual variation in response to a given amount of carbohydrate, the only way you can decide what foods make a healthy diabetes diet--FOR YOU--is to test each food you eat with your meter. If the food keeps you at a healthy blood sugar target, which, at a minimum should be under 140 mg/dl at 1 hour and under 120 mg/dl at 2 hours, eat it. If it doesn't, cross it off your list.

The main reason you've heard so much about the so-called glycemic index, is that it allows makers of high carb foods to market their damaging wares to people with diabetes as "health food." When the ADA chimes in with their magazines full of supposedly "healthy" very high carbohydrate pasta and oatmeal recipes, you can see how effective this marketing strategy is.

Too bad it causes blindness, amputation, kidney failure and heart attack death. But marketers (and the ADA) don't seem to worry about that kind of thing.

The one thing that has me scratching my head here, is this. Why is it that I could figure out years ago that the Glycemic Index was nonsense when PhDs and MDs can't. Do these people know anything about the physiology of diabetes beyond the "facts" that drug company salespeople, many recruited--I kid you not--from Big 10 Cheerleading squads--have told them?


matingara said...

Bravo! That is what i thought from the beginning - a gram of carb is a gram of carb. end of story.

the logical conclusion is that because the body converts protein into glucose (slowly and inefficiently) - that protein should be "marketed" as the ULTIMATE low GI food!!!

-- Joel.

Anonymous said...

Type 2 means your pancreas is not dead. It still has life and with proper diet you can live without being on insulin.in my opinion Glycmic Index may help them.

Jenny said...


It may be your opinion, but the research suggests that blood sugars that routinely go over 140 mg/dl after every meal will kill those remaining live beta cells.

Insulin used early in the diabetic process is MUCH more effective when there are living beta cells left, than insulin used late, when they are dead.

If you can eat low glycemic foods and maintain blood sugars less than 140 at all times, and ideally blood sugars that return to a baseline in the 80s, go for it.

If you can't, don't. The problem is that most people with Type 2 diabetes of any duration cannot.

Annie Nguyen said...

Hi Jenny,

This fact really worries me as i am just about to begin my final year project (i'm at University) on developing a low GI snack food. I wanted to put it as "suitable for diabetes", but after reading numerous articles and news, i think i better off removing that phrase....

And i must say your blog is very helpful for my research. It is always great to hear an insider's opinions on such a comprehensive and specific subject. Please keep blogging, and I wish you good health:)