My son’s blood sugar levels fluctuate at times even when proper carb-counting, insulin injections, and appropriate activity levels are maintained. Last night at supper blood-sugar check, he was almost 600 mg/dl [33.3 mmol/L] and was also spilling ketones. After an increased dose of Humalog, and more than an hour and a half, he was still over 400 mg/dl [22.2 mmol/L]. It was not until 2 am that he was in range. The doctor suggested he may be coming down with something. Could you shed some light on common reasons that children’s blood sugar fluctuates? What should you do about it?

Yours is a common question and a frustrating situation for anyone with type 1 diabetes mellitus. Most of the problem occurs because insulin injection is not as precise as we would all like it to be. For instance, there is some error in how well anyone can draw up a given dose on a syringe. Even when using a pen, there is lower error rate but still some. Small bubbles matter and whether you draw to the top, mid or bottom of a dose line also matters. To make things even worse, the insulin that is deposited under the skin is absorbed slightly differently after each injection. If there has been a change in activity, the blood circulation to that part of the skin is potentially different. In addition, of course, food is also absorbed differently from time to time and also depending upon whether there is a large or small amount of fat with the carbs. So you have three slightly varying factors and sometimes all three vary in the same direction, sometimes in opposing ways. If there is an infection brewing inside the body, then there is extra adrenalin and other hormonal factors that counteract the way insulin functions and this also can add to the variability.

If there are several days of wide variability, then it is not likely an infection. In the midst of a growth spurt, then more likely some other hormone factors are counteracting insulin action. Most other day to day variability can be decreased using more stable insulins (Humalog or NovoLog instead of Regular insulin, and Lantus instead of NPH or Lente insulins as basal insulin), using insulin delivered in small overlapping doses (MDI system), or using an insulin pump.

Some of us believe that paying attention to site selection also matters with more stability in the belly than extremities. In a four shot rotation, it may be more stable and therefore more predictable to use leg in the morning, arm at lunchtime, other arm at afternoon snack, belly at supper and buttocks/hip at bedtime and to not make other rotations at set times.

All this should be reviewed with your diabetes team so that they can help you identify possible causes of the variability and then possible solutions to try. Lots of this variability gets better after growth is finished in the late teens or early twenties.

SB