My son has started an intensive insulin management program.(looking to go on the pump soon) and is taking 21 units of Lantus, and an insulin:carb ratio of 1 unit of insulin per 11 grams of carb. We were told that he could try snacks without an injection and see how it affects is blood sugar level, but it seems as though he needs an injection for a snack larger than 15 carbs. However, we are a little confused because it seems that when he takes Humalog for a simple sugar, like a candy bar, the quick sugar runs out before the insulin, and he hits a low within an hour or so. So, I’m not sure if the spike of his blood sugar (without insulin) is worse or the low that seems to follow. Would lowering his insulin:carb ratio for quick sugars help this?

The concept of matching fast-acting insulin to carb intake makes a lot of sense, but has its limitations because we can’t always match the duration of the insulin to the timing of absorption of food. There is a lot of trial and error to this. A few thoughts to discuss with your child’s doctor:

Sometimes insulin/carb ratios need to be slightly different at different times of the day or may only work within a range of carbohydrate intake. This may be due to differences in how much “basal” insulin (in this case Lantus) is working at the different times of the day, to differences in factors that affect insulin action at different times of the day, or to differences in food absorption at different times of the day. Sometimes the insulin may work faster or last longer than when the food is being absorbed and digested.

In the case you describe, lowering the insulin:carb ratio for the snacks may help. Sometimes, some of the insulin given for the previous meal is still working at snack time, and you either need less insulin or no insulin to cover a small snack. If your son doesn’t want to take insulin before each snack as it is too many injections, you can try adding a little bit of Regular to the pre-meal Humalog or substituting a little Regular for some of the Humalog with the insulin given to cover the previous meal. The Regular may act a little longer than the Humalog and be enough to cover an in between snack. If you do this, he won’t be able to skip his snack. There is still a lot of “trial and error” to this process. Some people find the rules work better than others, and they can get more flexibility in the timing and amount of food than others.

If he switches to an insulin pump, you will be able to more finely tune the basal rate and will also have the option of giving a bolus (or part of bolus) for food over an extended period of time (called “extended or square wave” bolus or a “combination or dual-wave” bolus).

TGL