It takes a few weeks to get anywhere at first I'm afraid. But you'll get there.
I was really tired when I was diagnosed. One of the reasons I went to see the doctor in fact.
Then when I reduced my bs, I was even more tired as although I was insulin resistant, I'd got used to a high bs. The metformin helped on one hand with the insulin resistance but my bs coming down through diet negated that effect somewhat, until I got used to it.
So hang in there, exercise does help, but don't worry if you are tired, it does get a lot, lot better.
(The other thing to consider, while you are on a diet to lose weight, which is excellent, you also need to use the time now to test, find which food spikes you, and then adapt the diet to become a long term way of eating,. You'll find it becomes healthy food you like, and that is also good for you long term. A meter is vital now really)