A carb ratio is one of the many things to learn when calculating insulin doses. Quick acting insulin, which is currently Humalog, Novolog, or Apidra, is used to correct a high blood sugar and to cover the carbs eaten in a meal.
If you have heard that term “cover the carbs” and don’t quite understand what that means, it means that you let your child eat what his appetite says he needs, determine the carbs in what was eaten, then figure the amount of insulin needed based on a carb ratio.
So the more carbs consumed, the higher the dose of insulin to “cover the carbs.” The dose more accurately matches the food eaten.
So what’s a carb ratio?
A carb ratio is a number given by the doctor that tells you how much insulin you need to give based on how many carbs are eaten. Need help with counting carbs? Here’s a post on Carb Counting. The carb ratio can be different for every child, and even different at one meal than another. Sometimes it seems like the breakfast meal causes more spikes, so a lower carb ratio may be used.
If you are given a number such as 15 for a carb ratio, it means for every 15 grams of carbs eaten, you give 1 unit.
So an example would be:
Your child eats 45 grams of carbs. Your carb ratio is 15. You divide 45 by 15 and get 3. So 3 units would be the dose for that meal.
If your child is on a pump, the pump will do the calculation for you. If injections are used, that requires some math! This is why parents and kids with diabetes should be awarded honorary math degrees!
Several apps are available on smartphones that can do the calculation for you. Here’s one, but you can also search in the app store. Let me know your favorite apps you like for diabetes!
Determining the Total Dose:
To determine the total dose for each meal, a combination of a carb ratio and a correction dose is used. The total of these doses is the exact amount given for the meal.