Anger and frustration are part of the challenge when dealing with DM2 management. Lack of constructive communication with health care providers and the ever-increasing numbers of medications looms large. The idea that what worked well yesterday may not work at all today causes enormous frustration. Conflicting information regarding diet, exercise, lifestyle choices, health insurance issues, being attached at the hip to a pharmacy for life... you name it, there is challenge.
I don't know what the causes of your feelings are, so my answer to your question may come off as pat. Education, meditation and, faith may pull you through an acute rage. Sometimes we just have to feel our feelings and come out the other side. Physically, exercise is great stuff. Whatever you can do: walk, run up and down your stairs, lift milk jugs get outside and soak up sun... anything is better than nothing and feeling like a superhero when you are done is worth the price of admission.
Chronic disease teaches you to advocate for yourself. If you leave your doctor's office with more questions than you had walking in, there is a problem. Speak frankly with your docs, and if you aren't getting the information you need, find another doc and get a second opinion.
The takeaway is that we all feel these feelings, regardless of the cause. Don't let them derail you completely from taking care of yourself. I know, easier said than done. One caveat - if you find these feelings are overwhelming, find a good counselor - doesn't matter if it is a social worker, health professional or clergy. Find someone, not a friend, who can help you take the emotional charge out of your situation. Everyone needs a reality check now and then, especially we with chronic illness.
Good luck! I know this is not easy and the path isn't perfect. Do the best you can and that will be ample.