Ah yes, the great debate in the diabetes world; right next to, ‘what’s the difference between novolog and humalog’. When it comes to carbohydrates (carbs), are you supposed to bolus off of Total Carbs or Net Carbs? What are Net Carbs anyways? And why is the consensus so split?
What are Net Carbs?
Net carbs are total carbs minus fiber. For example, if your breakfast has 20g of total carbs and contains 5g of fiber, then the amount of net carbs would be 15g.
Some people bolus of net carbs and others bolus off of total carbs. But why would someone bolus off of Net Carbs instead of Total Carbs?
Why Would I Subtract Fiber?
Fiber is a type of carbohydrate that does not get digested by the small intestine (the place where food gets broken down and pushed into your bloodstream). And since the small intestine lacks the proper enzymes to break down fiber it therefore does not have any effect on blood sugar levels.
Fiber does not raise blood glucose levels because it is not broken down by the body, the fiber in an apple or a slice of whole grain bread has no effect on blood glucose levels because it isn’t digested. The grams of fiber can actually be subtracted from the total grams of carb you are eating if you are using carbohydrate counting for meal planning.
(Joslin Diabetes Center source)
Side note… If you’re wondering, ‘well then why the heck do I eat Fiber if my body can’t even digest it? I thought Fiber was good for you’. It is! It’s great for you! It isn’t until fiber reaches the large intestine (a place where it has no effect on blood sugar) that it gets broken down and eaten by your good gut bacteria.
It’s for this reason that many diabetics bolus off of net carbs instead of total carbs; Net carbs are the amount of carbs that your body will break down come digestion time. Net carbs are the amount of carbs that affect your blood sugar levels.
But I’ve Been Bolusing off of Total Carbs for all These Years…
Sometimes the amount of fiber in a food is so small that bolusing off of net or total carbs makes little difference. For example, if your snack has 20g of total carbs and 1g of fiber, bolusing for 20g carbs vs 19g carbs isn’t going to make much of a difference.
And if your diet is lacking in the fiber department then for the same reason above, you might not have noticed a difference between bolusing for net carbs vs total carbs.
This is sometimes why dietitians will say not to worry about subtracting fiber unless it’s more than 5g. However this is crazy talk because having an accurate carb count is the foundation to stable blood sugar numbers. Especially since some people (myself included) are sensitive to 5g carbs… and by bolusing for an extra 5g of carbs when my body isn’t getting 5g of carbs will most certainly drop me.
How Do You Bolus for Carbs?
I’m curious, how do you bolus for carbs? And what has your experience been like?
Earn good karma points. Share this with a T1D.