Three weeks ago, my 15 year old daughter, who is on four injections per day, was changed from Actrapid (Regular) to Humalog and she takes Insultard (NPH) at night. The problem is, she has very high oscillations in her blood sugar (with more tendency toward hyperglycemia). We are trying to figure out how to calculate her doses of insulin. Is there a method (an algorithm) to do this?

There are many “rules of thumb” to estimate insulin doses when insulin is first started or when changing insulin regimens, but you are describing a person who now has been prescribed very rapid-acting Humalog insulin with an intermediate insulin, the Insulatard. You did not clearly state this in your letter, but since you indicated that there are four injections of insulin daily, then I am presuming that there is Humalog at breakfast, Humalog with lunch, Humalog with dinner, and the Insulatard at bedtime.

The best avenue that you should take with this basal/bolus regimen is to properly dose the Humalog relative to the meals taken. Your daughter’s diabetes team (especially the dietitian) should talk with you about carbohydrate counting and give you guidelines as to how much insulin you should give for a given quantity of carbohydrates eaten.

The advantages of this regimen include increased flexibility to meals and activity planning, but it also requires the Humalog to be given with virtually every meal. So if someone eats three meals but seven snacks daily, they could conceivably require 10 shots of Humalog daily.

Discuss meal planning as suggested. Your daughter’s doctor might suggest that Regular (Actrapid) be restarted, with the dose based on carbohydrate counting, if the meals and snacks are routinely eaten. The Actrapid can cover the meal and subsequent snack, if dosed well. Other options include an even longer acting insulin than the Insulatard, called Lantus, in conjunction with the Humalog or perhaps an insulin pump. It is important to keep in mind that all of these basal-bolus insulin plans warrant careful and accurate carb-counting to dose the meal-time boluses appropriately.

DS