My nine year old daughter was diagnosed about nine months ago and still has sugar readings in the 400s and 500s mg/dl [22.2 and 27.8 mmol/L] at times. How dangerous is this in the future if we don’t get it under control?

In general terms, if the glucose readings that you get in the 400s and 500s mg/dl [22.2 and 27.8 mmol/L] are sporadic and rare, and if her overall glycemic control is good as reflected by her hemoglobin A1c, then I think these values now hold little worry for danger in the future. On the other hand, if the values are associated with blood or urine ketones, this in of itself can pose danger in the form of DKA [diabetic ketoacidosis], and that warrants more immediate attention.

If the values seem to have a recurring patterns such that they are often in these ranges at specific times of the day (for example, first thing in the morning) or if her HbA1c is rising, then she may well need ongoing adjustment in her insulin/meal plan/activity schedule as directed by her physician.

DS