My 10 year son was diagnosed four months ago and is still “honeymooning”. I understand the 1500 rule and have a good idea how much his blood sugar will be lowered by an amount of insulin. If he wants to eat birthday cake and ice cream in addition to dinner, is there a formula to determine about how much his blood sugar will go up with the addition of a certain amount of extra carbs (in this case about 90 grams)? Our pediatric endocrinologist ‘s response was, “Let him eat cake and give him a few extra units”, but could not get any kind of “formula” to figure out how much, although I know there must be one.

Usually, we estimate 1 unit to cover about 15 grams of carbohydrate, more if there is mostly fast acting carbs, less if there is significant fat and/or fiber with the carbs. However, everybody is a bit different so that this needs to be individually learned by doing enough pre-food blood glucose readings and coupling these with one to two hour post-meal blood glucose readings to see what you are achieving. Trial and error should answer this question.

You may also want to get some of the American Diabetes Association publications about carbohydrate counting to answer these questions. There have also been some nice summary articles in past issues of Diabetes Forecast. If you do this a lot of the time, there will be significant weight gain — so caveat emptor.

SB