The best site to begin with, I believe, is
Blood Sugar 101. She explains in laymen's terms what's going on with diabetes, what the blood sugar meter shows, what the different medicines do, and how YOU can take control of your own disease. She also has sections that go through various studies, and explains them clearly, because there's SO much info out there it's easy to be overwhelmed. It's not the prettiest site, but it's chock-full of amazing information. It was the first major place I started reading after my diagnosis with pre-D, and I'm SOOOOO glad I found it!
For a book, I've heard "
The First Year: Type 2 Diabetes" recommended over and over on the D boards. It is great for new diabetics, because we all deal with fear and denial and anger as we begin to accept that this disease will be with us the rest of our lives.
Another one that is recommended a LOT is "Dr. Bernstein's Diabetes Solution". He works with both T1 and T2 diabetics. He touts very low carb, at least to begin, so you can see how your body reacts to various carbs. Plus, he teaches the "law of small numbers", where if you are taking medicine to counter-act the carbs you eat, it's easier to estimate the meds when you eat small amounts of carbs than when you eat large amounts.
If she's on insulin, she might want "Think Like a Pancreas". It's also recommended on the D boards a lot, especially for those who are beginning to use insulin and need to understand how it all works.
I've not read these three books but these are the ones that get recommended a lot on the three D boards I follow.