My four year old daughter has type 1 diabetes and uses Humalog and long-acting NPH insulin. We have trouble figuring out how many grams of carbohydrates to give her in proportion to the amount of insulin she gets. She gets two units of NPH at night, and Humalog, although the amount of Humalog varies according to her dinner time and morning blood sugar levels. She also gets four units of NPH in the morning. Her lunch time and dinner time blood sugar levels are high, 200 to 300 mg/dl [11.1 to 16.7 mmol/L]. Are we giving her too many carbohydrates? Is there a scale or ratio of insulin to grams of carbohydrates for each meal and snack? And, is this wide range of blood sugar levels normal for children? We just seem so helpless at times and it is frustrating.

I think there are several things that may be needed to be looked at here.

First of all, it is helpful, I think, to review that different types of insulin have different times as to when they start to work and different times that they have their maximal effect (sometimes called “peak effect”) and different durations of practical effect in the blood stream.

So ‘N’ insulin (actually properly called ‘NPH’) is NOT a long-lasting insulin; it is actually an intermediate acting insulin with an onset of action of about two hours after you give it and a peak effect that is typically about six to eight hours later. The duration of action lasts a little longer than that.

Humalog insulin is a rapid-acting insulin. It begins to work within 15 minutes after an injection with a peak effect about 90 minutes later and shortly thereafter not much of a further effect.

So, if the lunchtime glucose readings are high, it may mean that the dose of Humalog is inadequate and/or that you are giving excessive calories (carbohydrates, typically) at breakfast. Are you giving a mid-morning snack? I feel that if a child is on Humalog, the typically prescribed mid- morning snack, such as was typically prescribed for the person on Regular insulin, is not required, given the duration of action of Humalog.

The evening/dinner time reading may be elevated as a consequence of the higher glucose at lunchtime or could reflect that the dose of morning NPH is inadequate.

You might want to talk to your diabetes team about reviewing the insulin types and dosages relative to the meal and activity plans. Perhaps starting to dose Humalog insulin based on carbohydrate counting is appropriate: if she eats many carbohydrates, then she takes more Humalog; if she eats fewer carbohydrates, then she takes less Humalog. This is the essence to initiating a more physiologic basal-bolus insulin plan.

DS