Adjusting Insulin for a Planned Activity

Family playing baseball

Most children welcome routines, but once in a while schedules change. If you don’t plan properly, the blood sugar balance may be upset. Parents, and in time children, can learn to assess the impact of regular events. Then when an opportunity for a new activity comes along, everyone will be better able to cope with the change.

Exercise both lowers blood glucose and increases the speed of insulin absorption by the body. For that reason, it’s a good idea to match it whenever possible with extra food. After a while, you’ll become more familiar with how your child responds to activity and you’ll have a better idea of how much food, if any, to offer. Some, usually older, children learn to decrease insulin on days of extra activity rather than taking extra food.

Here are some ideas to deal with planned activity:

  • In general, provide extra food for extra exercise. Children need about 10 to 15 grams of carbohydrate for every 30 minutes of activity outside the usual. This could come from a 4-ounce, or 125 mL, juice box, or half a sandwich.
  • If possible, check blood glucose levels before and after the activity. These levels will provide important information for future activities. For example, if the sugar level is very high after an activity, then less or no extra food may be needed. If the sugar level is low, even more snacks will be needed.
  • Always make sure children have enough food with them, especially if the activity goes on a long time or is off the beaten track. Examples of food could be glucose tablets, fruit roll-ups, juice boxes, or granola bars.
  • If your child starts to have a low blood sugar reaction, stop the activity immediately and treat the reaction. Don’t start the activity again until the symptoms have gone away and your child has eaten some extra food.

How to prevent delayed low blood sugar

  • Monitor blood glucose levels long after exercise. Lows can occur up to 12 hours later.
  • Children doing activities after supper should have a bigger evening snack. Doing a midnight or middle-of-the-night (2 to 4 a.m.) check will help detect late-night lows.

Extra activity: Michele’s story

Twelve-year-old Michele has always taken her ballet lesson on Saturday afternoon. To get ready for an exam, she’s planning to add an extra hour to the lesson. To prepare for the change in her schedule, Michele’s parents first think about her current routine. Michele always has an afternoon snack of a fruit and starch. The longer practice means that she’ll be dancing when her morning intermediate-acting (NPH) insulin is reaching its peak. Michele will be home for her usual 6 p.m. supper. Without the extra class, her blood glucose level is usually between 8 and 12 mmol/L (145 and 220 mg/dL) at suppertime. However, her blood glucose level often drops in the night after vigorous exercise late in the day. Michele’s parents work out the following plan:

  • Eat an extra fruit and starch choice before her second hour of dance.
  • Take blood glucose monitoring equipment to the lesson, as well as a small juice box and granola bar, in case her blood glucose starts to drop during the lesson.
  • Check the blood glucose level at the end of the lesson to see how effective the plan was.
  • Eat an additional starch choice at bedtime to balance the delayed effects of the exercise.

Another choice would be to decrease the morning dose of NPH by about 20%. You will need to monitor often to see the effect of this adjustment, and to detect or prevent hypoglycemia.

Marcia Frank, RN, MHSc, CDE

Denis Daneman, MB, BCh, FRCPC