Ask Dana: Rethinking the “Rule of 15”
by IDS Director of Technology and Applied Research, Dana Roseman, MPH, CDCES, RDN, LDN
- QUESTION
Dear Dana,
No matter how hard I try, every time I treat a low blood sugar, I end up way too high afterward. I follow the instructions from my doctor to give 15g of carbs and wait 15 minutes. What am I doing wrong?
Molly Weiss
Portland, OR
- ANSWER
Dear Molly,
You are not doing anything wrong; you are doing exactly what you were taught. But that is where the problem begins.
The ‘Rule of 15’ or “Eat 15 grams and wait 15 minutes” rule has been around for decades, but it has not been updated despite the fact that we have updated our way of managing diabetes.
For one, the ‘Rule of 15’ does not take into consideration if you are using an Automated Insulin Delivery (AID) system. These systems predict lowering blood glucose (BGs) and begin to reduce or suspend insulin that is being delivered sometimes long before the numbers are in a lower range. Oftentimes, if left without intervention, BGs will start to naturally come back up as a result of the insulin adjustments from the AID system. So, if using one of these systems, consuming 15 grams of fast-acting carbohydrates is just too much added sugar and there will be an exaggerated high BG as a result.
The ‘Rule of 15’ was also created long before we had directional arrows with continuous glucose monitors (CGM) and technology to help keep track of insulin on board (IOB). Depending on the rate of change of the BG or the amount of IOB, there may not be much need to use carbohydrate intervention. A rapidly falling BG with lots of IOB, however, there may be a need for a larger amount of fast-acting carbohydrates.
Additionally, the size of the person with diabetes matters. The glucose response is dependent on someone’s size, or body weight. An adult weighing 250 pounds will have a different glucose response than a school-aged child at 80 pounds. The amount of glucose needed is different for different individuals. These variables are not taken into consideration by simply following the ‘Rule of 15’.
It is also worth noting that being low and seeing a low CGM number are not always the same thing. Calibrating your CGM and making sure your technology is accurate is an important part of wearing technology. Many people will respond to alerts and alarms before checking with a fingerstick on a glucometer, and that can cause an unnecessary high blood sugar as well. These alarms need to work for you, not waking you up for a low in the middle of the night that is not really a low BG.
Learning how to treat a low BG is related to learning more about the way you are managing your diabetes.
If you are using an AID system, then using less glucose will also help prevent those rebound highs you are seeing. If you are unsure of why the lows are occurring, that might also be a good place to start. Using the fastest tool available in treating low BGs is also key. Sticking to a dextrose-based product will help BGs respond faster and help avoid feeding your lows long after they need extra sugar.
Foods containing protein and fat, like chocolate, cookies and candy bars, have a delayed reaction compared to dextrose-only products and will cause additional overtreating (even though tasting delicious!).
Learning to treat your lows is a vital skill for diabetes management.
While lows should be avoided with strategies and feeling confident in your diabetes management, lows are part of living with diabetes. But the treatment of the lows should work for you and not against you.
At Integrated Diabetes Services, we work hard to help folks like you understand their insulin delivery systems with the goal of limiting your lows and highs.
We can help you better understand how to treat your lows for your unique lifestyle and personal goals.
