Friday, November 18, 2011

Fun? With Advanced Carb Counting

The bad thing about diabetes management is that it isn't perfectly simple. The good thing is that, with glucose test strips, you can measure blood sugar any time and find out if things are working, so you never have to be in the dark if you don't want to be.

If you eat the same meals over and over, which is what Karl prefers to do anyway, you can nudge you insulin doses up and down until you hit your targets. The same meal at the same time of day should require the same insulin time after time. This trial-and-error approach means that the theory behind dose calculation doesn't have to be very precise, which is just as well, because it isn't.

We're using what's called "advanced carb counting," which we use like this:
  • Add up all the "net carbs" in the meal
  • Divide by Karl's "carb factor" (20 for breakfast and lunch, 16 for dinner)
  • Adjust if his blood sugar is high or low
  • Inject the indicated amount of insulin

What are Net Carbs?

Net carbs, or net carbohydrates, are "the carbs that matter to you." What these are depend on context. What kind of carbs don't matter?

  • Fiber doesn't matter, because it's not digestible and doesn't effect blood sugar.
  • Sugar alcohols, artificial sweeteners like sorbitol and xylitol, don't matter for people on the Atkins diet (at least, they don't matter for me), but they matter at least some to diabetics.
  • "Slow carbs" are in the same boat as sugar alcohols.

What We Do About Fiber

Fiber is technically a carbohydrate, but it's indigestible and has no effect on blood sugar, so if you give insulin for it, you're giving more insulin than you should, which can result in low blood sugars.

We were told to ignore fiber values under 5 grams, but if there were 5 grams or more, to subtract the entire amount of fiber from the total carbohydrates, and use this smaller number.

Why use two rules? Apparently, most people (a) hate subtraction, (b) have hardly any fiber in their diets anyway, and (c) don't much care about an error of up to 4 grams in their calculations. So the "Ignore fiber amounts under 5 grams" rule allows them to skip the subtraction almost all the time, at the expense of accuracy.

I find the five-gram rule more annoying and confusing than the subtraction, and I don't like the inaccuracy it imposes, so I always subtract the fiber.

What We Do About Sugar Alcohols

Most artificially sweetened candies, ice cream, and so on use sugar alcohols as sweeteners. If you're non-diabetic, sugar alcohols are "slow carbs" that metabolize so much more slowly than other carbs that they're almost like proteins or fats as far as low-carb diets are concerned. If you're diabetic, on the other hand, this doesn't seem to work. Being metabolized slowly is good, but it's not enough.

Apparently, different people react differently to sugar alcohols, and some people can count a gram of these as being equivalent to half a gram of ordinary carbs, but for Karl we have to count them at 100%.  This works fine (and it's what our diabetes team told us would happen), though it makes us wonder, "What's the point of using this stuff at all, if diabetic customers have to use as much insulin as with regular sugar?"

Fortunately, some low-sugar foods, like the no-sugar-added Umpqua ice cream that Karl likes, have zero-calorie artificial sweeteners doing most of the heavy lifting, though they also have sugar alcohols, so the total carbs really are a lot lower than with regular ice cream, with a half-cup serving of vanilla weighing in at only 11 net carbs.

What We Do About Slow Carbs

We like Dreamfields Pasta for low-carb meals. Karl isn't interested in pasta, so we haven't seen what effect it has on him. The word on the Web is that the "unavailable" carbs in this stuff aren't as unavailable as all that, and they get digested slowly over a period of hours, which is great for non-diabetic low-carb dieters, but for insulin-dependent diabetics, their mealtime insulin tends to run out of steam before the digestion is done, causing delayed high blood sugar.

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