Question from Aiken, South Carolina, USA:

My 14-year-old daughter has had type 1 for six years. In July, her basal rate was 1.9 units per hour. She started having frequent lows, which was unusual for her, so I began decreasing her basal insulin. A few weeks ago, I changed her insulin to carbohydrate ratio from 1:10 to 1:15 because the lows continued. She is currently down to 1.7 units per hour of basal. I changed her insulin sensitivity factor from 60 to 70 because all corrections were making her go down to around 50 mg/dl [2.8 mmol/L]. I do feel that she is pretty much done growing. Is this drastic change in insulin requirements typical at the end of puberty or is something else going on?

She had blood work for her endocrine appointment in July and everything was normal. The blood work included a thyroid screening. Her doctor also measures her thyroid at every appointment and it had not changed. She is only slightly more active since school has started, but the lows began prior to this when her activity level had not changed at all. In fact, she was probably less active when this began due to the extreme heat. She was spending most of her time indoors in the air conditioning.