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The 15 minute rule

Why are people with diabetes (PWD) constantly told to bolus (take insulin) 15-20 minutes before meals? It’s incredibly inconvenient, but let me share with you why we need to do it as well as a personal tip.

With insulin, timing is everything. Incorrect timing is the MOST COMMON reason for post-meal BG spikes. Why? Because current “rapid-acting” insulin is just not rapid. Carbohydrate digestion is much quicker and when a bolus is taken immediately before a meal (or worse, after a meal), the carbs are digested long before the insulin can effectively stabilize BGs. This causes a significant BG spike and then once the insulin kicks in, normalization (if we took the correct dose, of course).

So, if our BGs eventually normalize, why should we worry?

Current research regarding the development of DM complications has indicated that it is not only hyperglycemia and high HbA1c levels that lead to complications, but BG fluctuations as well. Plus, it feels terrible! If the bolus is given 15-20 minutes early, the insulin will kick in at the same time as carb digestion, eliminating the spike all together.

Commonly, when there is a significant post-prandial spike, it is thought to be due to an inaccurate dosage of insulin. Instead of strengthening your carb factor and giving more insulin for the meal, try giving the bolus earlier. If your timing is the problem, you may have been giving the correct dose all along. Increasing the amount of insulin given could potentially cause lows later.

So how do we know if our post-prandial spikes are caused by timing or by inadequate amounts of insulin? If the BG normalizes 4-5hrs after a meal (without additional insulin), then the problem is most likely time related. If the BG is elevated 4-5hrs post-meal, then insulin amount is more than likely the problem. If the BG spikes and is then followed by a low, then the problem is both; less insulin is needed and the bolus needs to be taken earlier.

Sometimes, planning can be difficult. It is not always easy to predict what you will eat or how much. I totally get it, and I have that problem often. Here is what I do…

On average, I eat about 20 grams of carbs or more with my meals. If I am not sure what I am going to eat or if I will finish my meal I input 20 grams of carbs into my bolus wizard 15-20 minutes before my meal. I call this my “pre-bolus bolus”. Then, once my meal arrives, I bolus for the remaining amount of carbohydrates. This allows my insulin to begin working early, while still reducing my risk of hypoglycemia if my meal is later than expected. This method is easily done with a pump, but can also be done with injections you will just need to take two injections instead of one). Try it! .

Anyone else have timing techniques to share?

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