May 29, 2003
Daily Care, Insulin Analogs
Question from Longview, Washington, USA:
My daughter is on twice daily injections of NPH with Humalog. Since Humalog peaks at two hours and is gone by three, is it necessary to give a morning snack? If the bedtime number is over 120 mg/dl [6.7 mmol/L], is it necessary to give a bedtime snack?
I think this is such an intelligent question! This means that you really understand the onset and peak actions of your daughter’s insulins. Once you know this, I think half the daily diabetes battle is over! (Maybe I think this is such an intelligent question because I agree with you!)
If the purpose of Humalog is to provide coverage for “a meal”, then you only need to dose it with the meal that is not being covered by other, later-acting insulins. So NPH with Humalog in the morning requires consumption of breakfast and lunch and perhaps an afternoon snack, depending on activities. NPH with Humalog at dinner requires consumption of dinner.
To really know whether a bedtime snack is required, then you need to know how “tight” the fasting glucose levels are and some 2:00-3:00 am glucose readings. Some people choose to give the evening NPH at bedtime, rather than dinner, and thus it will peak even later. In general, on the regimen you describe, I’d agree that if the bedtime glucose is 120 mg/dl [6.7 mmol/L], then no snack is required.
You’d be surprised how many physician’s “automatically” prescribe three meals and three snacks, not really analyzing the insulin doses/onset/peaks, etc.
Additional comments from Dr. Donough O’Brien:
To begin with, I would suggest a minor revision in your timing of Humalog’s action to one that gives the beginning action at 10-15 minutes, the main effect at 30-90 minutes with no effect beyond four hours. This has some bearing on your concern over the need for snacks. In this respect you might talk to your daughter’s doctor about switching to a new insulin called Lantus. This insulin ensures a peakless basal insulin supply for the whole 24 hours and if given at bedtime can be calibrated against the early morning blood sugar. This change has been shown to diminish hypoglycemia at night and with it the need for night time snacks.
Humalog with NPH at breakfast time avoids the need for injections at school. If the morning and supper time Humalog is given just after the meal then its dose can be adjusted for the pre-meal blood sugar and for the ‘carbs’ actually consumed. Such ‘intensive’ therapy makes it possible to adjust the insulin dose much more closely to the carbohydrate load at conventional mealtimes and thus diminish the need for snacks.