My 11 year old daughter was diagnosed with type�1 diabetes at the age of five. For the past three weeks, her blood sugar has been erratic ranging from 300 to almost 600 mg/dl [16.7-33.3 mmol/L] during the day. Her eating habits,exercise, and school have not changed prior to this. How much do hormones affect blood sugars in a girl this age?

I presume you mean hormones of puberty (estrogen primarily in girls — but they also make some male hormones, too). Yes! Those pubertal hormones can play a large role, but not usually the sudden and dramatic changes in glucose as you imply.

I’d consider looking at more immediately rectifiable solutions for now like:

Changing bottles of insulin. After opening, Insulin bottles should be replaced every 30 days. Even if you have had a relatively new bottle, if things go funny suddenly, I’d look for “bad” insulin as the culprit first.
Look for a concurrent illness. Her physician can guide you here.
Watch the meal planning really carefully. Extra snacks or timing of meals during the crazy holiday season?
Teens (and pre-teens) do periodically miss (or even deliberately omit) doses of insulin, and would never admit to do doing so. Sometimes it is attention seeking; sometimes to get ill enough to get to miss a test a school, sometimes as a matter of weight control — especially, it seems, in girls. Can you actually provide her the insulin injections for a week and see what her sugars do?

If she has glucose readings this high, I hope you are checking her urine (or blood) for ketones.

DS