This is to Neliii:
Two of our kids have type 1, one dx at age 18 mos and she's now 8yo. The other is our eldest son, who was dx just over a year ago at age 22yo.
I highly recommend a great website: www.childrenwithdiabetes.com
It's full of very good information, research, advice and btdt experience. Their CWD Forums are the best and you can learn a lot from reading there. They have one for adults too.
One of the reasons it's common to gain weight after a type 1 dx is because once you are getting insulin via injections or pump after your beta cells have quit producing it, your body no longer has to burn fat for fuel. That's a basic way to explain it. Get a good carb counting book, a scale if you want to weigh your food for more accurate carb counts. I think the Calorie King book is a good one.
I've thought about becoming a CDE eventually, since I have personal experience with 24/7 management of a child with diabetes. I'd have to learn a lot about type 2's and the other aspects, though.
Good luck to you!