As most parents, we want to keep our son’s control using as few as possible shots. He’s now six years old and we have been doing okay with two shots a day mixing NPH and Humalog. Now, his averages are higher than we want, 140 to 150 mg/dl [7.8 to 8.3 mmol/L]. I’ve read there are some forbidden insulin mixtures, but this is not clear to me. Which are the insulins that could be mixed?

While it is reasonable to consider fewer shots, you pose some problems for achieving control and flexibility with this approach. Most of the intensified treatment regimens utilize combinations of basal and bolus/prandial insulins. You can mix Regular and NPH, Regular and Lente, Humalog and NovoLog with NPH. Lente insulin is being taken off the market in the U.S. so it will soon become unavailable since it is so rarely used. Same with Ultralente. Lantus does not mix very well with most insulins and this is not recommended. The most common approaches are Humalog or NovoLog before meals with bedtime Lantus; if the Lantus does not work for a full 24 hours, then a small amount of morning Lantus is added for a twice-a-day Lantus basal insulin regimen coupled with three to five doses of analog insulins to cover meal time excursions. Another previously popular regimen involved fast acting insulins (analogs now supplanting regular insulins) at breakfast, lunch and dinner plus NPH at breakfast and bedtime; problems with peaking of NPH especially in the middle of the night limited its use to get all the way to the next morning. All of these should be based upon food intake since this changes considerably in different cultures (i.e. big meal at 1 to 2 p.m. instead of at 5 to 6 p.m. requires different insulin strategies; time of bedtime also important just as number of snacks). We would make such decisions based upon detailed detective work with frequent blood glucose monitoring to determine patterns and then try to match the food and/or insulin regimens available on this basis. I would urge you to work closely with your diabetes team to determine A1c and blood glucose target goals and then see how these may be matched for you and your child.

SB

[Editor’s comment: Recently, some endocrinologists have been experimenting with the mixing of Lantus and NovoLog in the same syringe (see a recent question). It is important that the mixed shot be given immediately.

BH]