I have a 7 year old son who has had type 1 diabetes since he was 2 and 1/2 years old. He gets 4 units of Humalog and 12 and 1/2 units of N in the morning. When does the N insulin start to work? I’ve heard that the N peaks at different times for different people. When is the best time to check him to determine when the N is peaking for him? His readings have been high (300 or over) in the afternoon. We want to know if he needs more insulin or if he may be getting low and having a reaction.

The generally accepted ranges for NPH insulin to act is that it starts in 2 to 4 hours, has maximal effect between 6 and 8 hours and is all gone in between 12 and 15 hours. From the rest of your question, I take it that what you really want to do though is to assess control in the latter part of the day and at the same time be sparing in the need to do extra needle sticks. The first step would be to talk to your son’s doctor about an A1c or glycohemoglobin test. You may have been taking these every three months or so for a long time; but if not, they are a good indication of the overall level of blood sugars for the past three months. At the same time they reflect an average so that a ‘good’ value might be exactly that or it could be a mixture of levels, some of which were too high and some in the hypoglycemia range.

The other component , and I sense that this may not be a popular one, is to build up a profile of blood sugars that includes an occasional one in the middle of the night that will help you decide both on an average pattern of blood sugars and also tell you something about the effects of vigorous exercise and the vagaries of appetite and mood.

With all this information I think it may well be that you will decide that your son needs some realignment of his insulin dose with a second injection before the evening meal; but again this would be something to work out with the doctor. Something to look forward to though will be to try wearing the GlucoWatch sometimes on his calf or to wait until the smaller version is available.

To solve this issue is important because in the next few years I am sure there will be pressures to start moving towards some form of what is now called intensive insulin therapy, whose objective is to minimize the chances of the long term complications of diabetes.

DOB