I'm sorry about your daughter's recent diagnosis. When either of you have questions be sure to check here. People are really knowledgeable and there are a lot of teens.
I was developed a ????Necrobiosis Lipoidica Diabeticorum on my shin when I was about 10. At that point I'd had diabetes 6 years. For a long time it was dark red and shaped like Italy. People usually thought it was a burn from a motorcycle exhaust pipe or some kind of scrape. It's actually provided a good way for me to tell people I'm diabetic.
Over the years the shape has blobbed out and it's gotten veiny and lighter in color. I wasn't self conscious about it when I was younger, but stopped wearing shorts a few years ago when it got veiny.
As a kid I had steroid injections around the perimeter but they were incredibly painful and didn't help the spot at all. I've seen other posts online from people who had success with steroids or with newer laser treatments.
????Necrobiosis Lipoidica Diabeticorum happens in diabetics and a few non-diabetics. The skin is more fragile there and doesn't heal well... still have a scar on mine where I got kicked playing soccer as a kid.
Guess they're fairly unusual. When I was in the hospital after giving birth to my son, one of the doctors noticed I had it and I became instantly popular with the interns who'd read about them in med school but hadn't seen one in real life.
Take care. -Jenna