January 24, 2014
Daily Care, Insulin
Question from Stow, Massachusetts, USA:
How important is pre-bolusing before meals? My 11-year-old is at school and doesn’t always know how much he is going to eat (we have lunch provided and students do not bring a lunch). The nurse checks his blood sugar. then looks at his plate and gives him a bolus. Sometimes he begins eating before the bolus. Is this a bad habit to start with him? How do we help him wait to pre-bolus when all the other kids are eating around him? My wife and I are concerned about the habit he is developing around eating and not bolusing until later. What if he forgets to bolus?
Pre-bolusing before meals is very important to overall glucose control, as shown by a study published in 2010 (Timing of meal insulin boluses to achieve optimal postprandial glycemic control in patients with type 1 diabetes). Based on this study, a bolus of rapid-acting insulin 20 minutes prior to a meal results in significantly lower postprandial glucose levels than when the mea bolus is given just prior to the meal or 20 minutes after the meal.
This graph, from the study referenced above, clearly shows the dramatic impact of pre-bolusing on post meal glucose levels:
Another study (Poor adherence to integral daily tasks limits the efficacy of CSII in youth) from 2011 reported on the impact of missed meal boluses. To summarize:
Missing breakfast boluses twice a week results in a 1.0% increase in HbA1c Less than two food boluses on any day within two weeks results in a 0.8% increase in HbA1c Seven or more boluses per day for half of the days results in a 1.0% decrease in HbA1c
Given the importance of pre-bolusing, I would recommend working out a schedule that allows your son to check his pre-lunch blood sugar and pre-bolus at least 20 minutes before lunch, rather than immediately before lunch.