So, I was reading To Think Like a Pancreas (as I’m often found doing these days) and I got into Chapter 7 - Bolus Calculations. I am continually learning SO much! So…I read about something called the Glycemic Index of foods, which most of you already know plenty about…but I knew NOTHING, literally zero, about it…BUT…it from my understanding, it sounds like GI DETERMINES how little, or how much our BG “spikes” after a meal. The higher the GI (100 being the ceiling, which glucose has an index of), the more rapidly the blood sugar rises after meals. KNOWING GI of different foods and knowing when to bolus can SIGNIFICANTLY cut down on the “after meal” spikes…spikes that we are experiencing with our son.
So…
I took some of his common foods and I created an Excel workbook to show how they rate on the GI scale, as well as other factors, then, based on those, I have a “guide” (that I will be adding too) for when we should bolus our son for meals. I have included a screenshot and attached the workbook if anyone finds it of interest. I know I find tremendous benefit from it because, if GI matched with BG levels is done correctly, spikes can be controlled!
The IF-ELSE formulas used for two columns where formulas were used are as follows:
Column Formula
“High, Moderate or Low GI?” =IF(B2 > 70,“High”,IF(B2 < 45,“Low”, “Moderate”))
“Bolus When?” =IF(C2 = “Moderate”,“5 - 10 Minutes before Meal”,IF(C2 = “High”,“20 - 30 Minutes before Meal”, “Bolus soon after eating or Split the bolus into two parts; 25 - 33% directly after meal and the rest over 2 hours”))
I don’t use glycemic index in any scientific way but I do understand its basis. All other factors held equal, the glycemic index determines how fast BG will rise after eating. It is the total quantity of carbs that will determine how far the post-meal BG will elevate.
The GI factor, however, interacts dynamically with pre-bolus insulin timing, exercise, insulin dose size, and the quality of all the other food eaten at the same meal. It’s interesting to note that the order in which the food is eaten can also be a factor in post-prandial BGs.
I will generally avoid high GI foods like fruit juices, steamed carrots, and mashed potatoes when I choose what to eat. Any breakfast cereal, whether it contains any added sugar or not, will always skyrocket my post-meal BGs. Oatmeal is a little slower, but I avoid it as well. For me, bread will act as fast as directly eating spoons-full of table sugar.
Yes, “How many” carbs you eat will determine how much insulin you need to get, but the GI of the carbs you eat (along with BG level) determine WHEN you should receive the insulin.
Agreed. I find the GI of foods mildly useful for dosing insulin. The quantity and timing of carbs relative to the insulin dose is a much weightier factor in my calculation.
I have heard Gary speak on this subject. Basically he says that with T1, GI is an “indicator” of whether the carbs will digest slow or fast. A carb is a carb. And the GI confuses things because you can eat simple carbs with fat and essentially make them low GI since they will digest slower. And the Glycemic Load (GL) is just the carb count. I somewhat account for GI in my timing and injection strategy but the amount of protein and fat in the meal is just as important.
I also consider the GI index concept as more of a general concept than an exact mathematical formula that I follow… It’s certainly an important underlying understanding that different types of carbs process at different speeds… I take it into even more consideration with afrezza than I do with injected bolus…
If I have both Apidra and a somewhat slower bolus insulin like Humalog or Novolog in my quiver, I’ll choose one or the other, or even both, based on how many carbs in a meal are high GI. This works pretty well for me with an MDI regimen.
For my T2 hubby who has not yet converted completely to low carb, the GI is helpful in meal planning. For my T1 daughter it had limited use when she was forced into higher carb by her insulin regimen, & almost no use at all since going on the pump & back to low carb. Protein & fat content is more helpful in determining a bolus for her, particularly in deciding how long to extend it.
The biggest complaint I have is it doesn’t consider important data (ripeness of fruit, cooking method/timing etc) in the impact on BG.
The biggest reason Glycemic Index is a factor is that Type 1s don’t produce amylin. So, while our fast-acting insulins take a while to kick in, we digest our food a lot faster than insulin normal (and Type 2s), which causes BG spikes. It makes it much more difficult to predict how a certain food will impact BG.
High levels of fat in food can cause slower and delayed glycemic action, which makes places like Olive Gardens or high-end steakhouses dietetic annoyatoriums.
“Hey, my BG is great after two hours…”
Cue to four hours after that, “Three frakkin’ fifty! Due I need to change my set?!”
This is a classic example of YDMV. I don’t find the GI very useful, partly because I just avoid a lot of the high-GI foods to begin with, irrespective of GI considerations, and partly because it doesn’t seem to make as much difference for me as it does for some others. I’m super-sensitive to carbs no matter what form they’re in. For that reason as well as others, I prebolus pretty religiously to suppress the extreme peaks (unless I’m dining out, a peak much over 140 is a rare event). I also eat LCHF, so my meals are dominated by protein and/or fat and digest more slowly because of that, too. We each have to play the hand we’re dealt.
But, as mentioned, YDMV. For some, GI is a very potent yardstick. C’est la diabetes.
This study shows that the GI varies a lot between members of a population and even within the same member at different times. This makes any broad generalizations difficult to make. We can figure out what foods will rocket our post-meal BGs if we eat to our meter, and usually drop those foods from our diet. As I said before, the whole concept of a glycemic index as an everyday tool for me is only mildly useful, at best.
I have read the study and I have heard what everyone’s said. Having said that, I can promise you that I will thoroughly test this on MY son to see if there is any applicability. Studies (or, a single study) as well as other peoples perspectives help me in making my determination on importance, but before I firmly believe one way or another, it will require testing, which I definitely have in progress. If it works, it’ll be another tool! If it doesn’t, at least it was thoroughly tested!
I think we should all use every available tool we have to the best of our abilities. None of them are perfect, but they’re what we have for now. But we also have to remember that because something works perfectly (or fails) one day, there’s never a guarantee of the same results the next day. Lower GI foods can also be some of the most difficult to bolus for, so learning to use the extended bolus with a pump is very important. I have a feeling you’ll do fine.
GI was most useful in my daughter’s case for determining menus & the order she ate each food. If I served a higher GI food, she started with a protein or fat to slow the spike. She still eats that way now, just with lower carb foods.
Those two examples were not hyperbole, but my last two big family get-togethers. My nephew making Eagle Scout and then that same young man and his girlfriend graduating high school.
The second place was Daniel’s Broiler in Bellevue, where I had the Veal Rib Chop and garlic mashed potatoes, which had garlic and equal parts butter and spuds. Yum!
I see the Glycemic Index as a good first-pass guide when deciding when to bolus. So let’s say we’ve never eaten, buckwheat before… do I bolus all upfront, prebolus by a significant amount, combo bolus for the rest after the meal? Depending on the GI the answer may vary.
But that’s just the first pass. You’ll soon realize that your child’s response to foods is both variable and very determined by the precise food. So I use the GI as a good indication for unknown foods, but rely on a food log (a book I keep recording timing and dosing of insulin for given foods and then BG over the next several hours) for the second time and onward. I think it’s ultimately more useful to have a list of foods like pizza, pasta, pancakes, etc. and then base your bolus off historical responses to these specific prepared foods, rather than trying to determine how the component parts that have been processed, cooked and mashed together interact. And though it is annoying for record-keeping, the more detailed the better: A pancake at this one brunch place we go, which is roughly the size of Andre the Giant’s head, has a totally different BG profile for us than one at our neighborhood joint that presumably is not just smaller but uses a different recipe.
The other thing is that with my son, if he eats more than, say, 50 grams of carbs, his stomach is full and his body is fully occupied with digesting that food, so we often wait to bolus for the some of the carbs till we see a slight rise. My estimate is that he typically can’t process more than 30 grams of carbs per hour, so I usually won’t bolus for more than 30 g upfront. He was at a birthday party recently and ate some ungodly amount of totally unhealthy carbs – cupcakes, cake, juice chocolates, and flaky pot pie – maybe 120 grams of high GI foods over a 3 hour period? He never spiked above 130 and was continually low and we had to give him gummies and glucose tabs on top of that because we made the mistake of not waiting to bolus for all those carbs until his stomach had a chance to catch up.
