Not all carbohydrates are created equal...?

I’ve noticed that sometimes, with prepackaged foods, the listed carbohydrate counts don’t seem to match up with my insulin requirements (carb counting on an insulin pump).

I can explain some of the issues, but not all. Examples:

  1. At work, I almost always bring my lunch. Sometimes, I bring frozen meals. If I take a frozen Asian meal that lists, say, 50g of carbohydrates from rice plus whatever carbs might be in the sauce and/or vegetables, for this brand, I usually have to tell my pump I only had about 35g. Otherwise, I go low. Every time.
  2. For breakfast, I often eat various flavors of granola bar. I always take insulin for the exact carb count listed on the package. But my blood sugar always spikes rapidly after eating them. I guess the carbs digest too fast for the insulin? The effect is less noticeable if I give myself a longer lag between taking the insulin and eating, but that doesn’t completely prevent it.
  3. Pizza. If I eat restaurant pizza from literally anywhere, I have to take the published carb count and add about 50% or I go high. I’ve found it works best if I take the insulin in stages, some before I eat, some during, and then some after. I’m guessing this is the high fat content coming into play?

I’m careful to make sure I count these correctly, taking into account serving size, etc., so it isn’t that. And these are not one-time events but a steady pattern that I see every time I eat specific foods. There are other instances where I mess up my blood sugar that might be from mis-counting homemade foods or etc., but these are cases where I’m not having to estimate the quantities. They’re literally on the package.

Do you ever have problems with carbohydrate counting like this? Is this because different carbs digest at different rates or that some spike blood sugar levels differently? Or am I just finding that not all packaging is accurate?

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To answer your questions - YES, YES and YES!

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A bit more in depth (pun intended?) …

I find some nutrition label carb counts to be consistently “wrong”. In part, this is because there is actually no testing required to ensure the amounts of carb, protein, fat, fiber etc found on nutrition labels are accurate. It is strictly up to the food manufacturer to place the label there. I like to think of what I learn as just part of MY YDMV solution, so for certain foods produced by certain companies I modify my bolus accordingly. One example for me is 100% juices with cranberry. The labels suggest 35g carb, I bolus for about half.

Next you add in the glycemic index for the food you’re eating, then you have to factor in the effect of added fat and protein (pizza!)

Bottom line is I use the labels as a guide.


It is quite frustrating having to take those labels as guides rather than set values. I mean, I get that fresh foods can have variances – this apple has more carbs than that smaller apple. But a processed food should be fairly predictable over time, I would think.

I do know that some companies do test the label values for accuracy. I worked a little over a year for a food safety / quality laboratory that did such testing (along with salmonella and other microbes). But they tended to focus more on things like vitamin / nutrient quantities than fat, protein, or carb quantities, if memory serves. And, of course, some manufacturers are more diligent about such testing than others!

And then there are the combinations in foods as well as of foods. Combine carbs with fat and/or protein and your digestion time lengthens. Eat a lot of protein, and the carbs generated take hours to appear. The way to counter that is with extended boluses. I use 60/40% (a lot of the time) over 2, 3 or 4 hours, depending upon the food. With MDI I used to inject a bit up front, a bit an hour after eating and a bit maybe 2 hours afterwards. Hard to do with MDI.

Before I switched to this new “closed loop” insulin pump, I used the various extended bolus options pretty often.

Now I kind of have to cheat to achieve that goal, by giving some insulin up front, then adding more “carbs” mid meal and a few more at the end of the meal. Not ideal, but it works.

In the FWIW and WYGNBTD (When You Got Nothing Better To Do) categories, here’s a link that describes what the FDA (USA) tells companies they should do w/r/t nutrition labeling. NOTE: It’s all voluntary.

Nutrition Labeling Manual

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I bought some rolls once, 8 rolls for 16 ounces. I used the carbs-per-serving listed on the package, and was still high! Then I thought to weigh a roll, and guess what? it was about 25% heavier than the package indicated. They can get in trouble for selling less than the package weight, but I don’t know if there are any penalties for selling more. When in doubt weighing is a good idea.

I think the cause of carbs reacting differently to the listed carb amount is because manufactured food does not contain the carbs home cooked food does. Pastry, for example, rarely uses wheat flour. Flours like rice flour, potato flour, tapioca flour would have a different effect on your blood sugars. Try to avoid manufactured foods with numbers listed on the ingredient list, it is not only healthier but also easier to manage your bgs.

Yeah, this is a real PITA to figure out until you can get good with the actual carbs / fat / protein in a particular food. Using the extended bolus feature, I have been able to just about wipe out highs, but it is a bit tricky and even when I think I have it right, sometimes something slips in that requires a correction. For me personally, I need 3 - 3.5 hours for high protein meals to digest, so I take 40% of the protein in grams and bolus for that over that extended time. Generally it works pretty well.