Why the Glycemic Index is Crap if you use Insulin

I like to click on the ads here to support the site. So I checked out one advertising info about the “Glycemic Index” and further clicked through to the list they’ve published of the glycemic indexes of foods. The page is headed with a carb-porn picture of a huge loaf of bread.

That made me think it might be a good idea to direct your attention to this blog post I published a couple weeks ago Why The Glycemic Index Fails for Many People with Diabetes

Do check this out. It’s really disturbing how many people with Diabetes are told to eat foods their bodies can’t handle because they are better for people who DON’T have diabetes.

For those T1’s (like myself) that have chosen to keep carbs as a significant part of our diets, the GI is very helpful. It’s just one more tool in my toolbox that helps me manage my T1. Since getting my CGMS it becoming even more useful.

It’s all about timing. Timing my bolus activity with the digestion of low GI food is a lot easier than timing it with high GI food. Both can be done and still keep post-prandial below 140 (often even 120), but it’s simply easier with the low GI foods.

You’re right about pasta, that’s very tricky (but with a pump and CGMS you can still keep BG’s under control while enjoying a small serving of yummy spaghetti).


It sounds like with your pump/CGMS combination you are able to simulate 2nd phase insulin response.

Using shots and limited test strips, I don’t see that much difference with most of the supposedly low GI foods. Oatmeal, brown rice, and most whole wheat bread. The sourdough wholewheat that could double as a doorstop is slower, but a slice also tends to be larger because it is so dense.

No way my insurer will ever pay for the fancy equipment, either. They just wrote an exclusion into my coverage specifically aimed at the CGMS!

I honestly have no idea what the GI is of most of the foods I eat, but I do know that my bloodsugars do much better with high fiber carbohydrates than with processed carbohydrates. Of course, I don’t really like bread, and I keep my pasta or rice to one cup at a time.


You’re right, with a pump & CGMS I can combine 2 boluses to function very much like an actual healthy pancreas. The difference between oatmeal (low GI) and corn flakes (high GI) isn’t huge, but you can see the difference on the CGMS. The difference between carrots (moderate GI) and broccoli (very low GI) is more evident.

But trying to emulate this with MDI and finger tests would not be near impossible.

Y’know - it’s enough work to keep track of what has carbs and what doesn’t. I don’t burden myself with figuring out what carbs are faster than other carbs. It’s a simple matter for me to bolus a good 15 to 20 minutes before eating.

I don’t ignore the type of carbs I consume. I know for instance that the carbs in an extremely ripe peach are going to have a more severe affect on my BG than a crunchier peach of the same size. I know that high-fiber bread is going to have a less severe affect on my BG than as similar slice of so-called ‘whole wheat’ bread.

The differences in the GI index of food on the various lists I’ve seen seem so inconsequential as to be meaningless to me.


I agree with you completely - I pretty much can’t eat carbs of ANY kind - they all shoot my sugars up - fast or slow - it doesn’t seem to matter - they just go UP!