Prebolusing improves A1C

 In a recent study of 4768 participants of the T1D exchange, a nation-wide consortium of clinics and electronic health records of persons with diabetes, one simple behavioral change has been shown to have a major impact on A1C reduction.

This study found that persons with diabetes, using fast acting insulin to bolus for meals, showed a marked reduction in A1C when bolusing before a meal rather than during or after that meal. Persons who bolus before eating had an average A1C of 8.4, while those who bolus during or after the meal averaged and A1C of 8.8. Those who bolus before the meal, also called pre-bolusing, are also 1/2 as likely to forget to bolus for the meal entirely. Persons who forgot to bolus for a meal more than once a week had an average A1C of 9.8 and were nearly twice as likely to experience a DKA event! This study clearly shows that one small adjustment in when we give our insulin can improve our overall glucose control and reduce our risk for dangerous high blood sugars.

The reasons or the differences are twofold.
First is that it is simply all too easy to get caught up once a meal has begun. From sharing a meal with friends and family, or simply enjoying the food, a plan to bolus after the first bite is very easy to forget. By the end of the meal we may get a phone call, kids interrupt our train of thought, or we clean up and just never think back to that bolus. Our minds go on “autopilot” with tasks we perform routinely. It becomes very easy to forget a bolus once we begin a meal because the exact timing does not stand out. We remember the time we bloused in the past as if it had just happened. Time passes and we find ourselves looking at the insulin trying to recall, did I bolus? Best case scenario; our blood sugar goes high, we catch it with a post-parandial blood sugar check and correct. But, we all know those corrections can take hours to bring us back in range, so we are looking at hours of elevated blood sugars. Worst case scenario is when this happens at a dinner meal, we go to bed without checking blood sugar and wake up to blood sugars still high, perhaps even dangerously so. In this case we have spent nearly 1/2 of our day with elevated blood sugar levels.

Secondly, the rapid acting insulin we use to bolus for meals is fast, but not nearly as fast as carbohydrates are absorbed into our bloodstream. Bolusing during or after a meal gives the carbohydrates a long head start on insulin action. This means that rather than heading off high blood sugar and maintaining relatively level blood glucose control like our pancreas would, insulin is constantly battling our blood sugar down from the heights. These spikes leave us at higher risk for micro-vascular complications as well as DKA.

Ideally, taking rapid acting insulin ahead of a meal by 15-20 minutes allows insulin action to most closely match the blood sugar rise after eating. This one change can vastly reduce time spent with high blood sugar. As the study shows, changing the timing of meal bolus to pre meal dosing can have a major impact on our wellness and A1C goals with minimal change in our lifestyle.

There are times when bolusing before a meal would not be recommended. First is anytime blood sugars are low or trending toward low quickly. In these circumstances it is best to hold bolusing for food until blood sugars are back within target range, and to only bolus for the carbohydrates eaten beyond those needed to raise blood sugar to the target range. Another time pre-bolusing 15 minutes in advance would not be recommended is if one is eating out and not sure when their food may arrive. It would be safest to wait until food arrives before bolusing to ensure that we are not stranded with a lot of insulin on board, gulping down glucose tabs or juice instead of the meal we had planned. Pre-bolusing with a very slow digesting meal such as high fiber, high protein meals may not require the additional 15-20 minute pre-bolus for persons using injection therapy (a split bolus dose may be helpful). For those using pump therapy pre-bolusing coupled with an extended bolus allows for the benefit of pre-bolusing without risking an initial drop in blood sugar.

For more information on adjusting your bolus timing to improve your blood sugar management contact Integrated Diabetes Services. Our educators would be happy to help you find the best strategies to make the most of your therapy options and fitting them into your lifestyle.

For more information on this study, you can view the abstract here https://www.ncbi.nlm.nih.gov/pubmed/28895431#

For more information on this study, you can view the abstract here https://www.ncbi.nlm.nih.gov/pubmed/28895431#