Because both soluble and insoluble fiber aren't digested and absorbed in the digestive tract, they doesn't raise blood sugar the way that digestible carbs do. However, some people with type 1 diabetes report that eating large amounts of fiber does seem to affect their blood sugar as a result of intestinal distension. For example, Dr. Richard K. Bernstein, a physician with type 1 diabetes who specializes in diabetes management, has spoken of a patient who experienced a pronounced spike in blood glucose level after eating a large head of lettuce that contained very few digestible carbs.
Generally speaking, though, it is best to deduct all fiber carbs from the total in order to avoid injecting more insulin than needed. Therefore, if you eat a meal containing 25 grams of total carbohydrates, 7 grams of which are fiber, it is safest to bolus for 18 grams of carb. However, if you find that your post-meal blood sugar is consistently too high when you deduct all fiber, you can try bolusing for only half the fiber carbs, which in the above case would be 21 grams of carb.
Answered By dLife Expert: Franziska Spritzler, RD, CDE
Certified diabetes educator and registered dietitian living in Southern California.
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