What is the difference between giving my three year old daughter her injection of Lantus at bedtime versus morning? If Lantus works for 24 hours, why does it matter what time it’s given as long as the time stays consistent?

You are correct: If Lantus does in fact remain effective for near the full 24 hours, then it would make no difference when it could be given, as long as you are consistent. In fact, Lantus is now approved for administration in the morning as well as the original indication for bedtime.

The problem arises because clinical experience is showing that some children are relatively “fast metabolizers” of Lantus and it may not last the full 24 hours! Thus, if you give at night, then you KNOW nighttime is covered and if it “wears off” in the middle of the next day, you can adjust by giving a little extra short-acting insulin or adjusting the diet.

But if you give in the morning, and it does not last the full 24 hours, then the child may be relatively deficient in insulin in the middle of the night when everyone is asleep, thus leading to potentially higher, and maybe more worrisome glucose values in the early morning hours.

The way to assess? Check those glucose levels.

I remain partial to bedtime Lantus.

As an aside, as far as I know, Lantus has not yet been FDA approved for use in children under age six years. I may not be current and this does not mean that your physician cannot prescribe Lantus to your preschooler; it means the FDA has no data to show efficacy and potential ill effects in that population of diabetics.

DS