Breath a sigh of relief - you'll be in good hands soon.
Sorry you had to go through such difficulties with your GP. Sounds like you've got a few more things to address than he could handle but, he's doing the right thing by referring you now. To be fair, most GPs follow a pretty standard protocol when faced with patients with blood sugar issues. Most patients get with the program fine but, there are some with added issues that would require a specialist. Lucky you
The Endo is the endocrine and metabolism specialist. I like to think of them as the "hormone" docs. He may order more blood tests to check thyroid and cholesterol levels and/or urine tests to check kidney function if you haven't had them already done. He'll basically get an idea of how your body functions metabolically, look at the meds you're on, and determine the best course of action. Keep in mind that sometimes it is trial and error and that changes in regimen (meds, diet) can take some time to get figured out. Everyone is unique when it comes to the D.
Keep your GP for the aches, pains and colds but the blood pressure, diet, and meds will be in the hands of your Endo.
Cheers.
Kris