Recently diagnosed with diabetes and have noticed an extreme change in my vision. Who should I see?

Temp vision change. More than likely your vision will shift back once your blood sugar has been lowered and stabilizes for 4-6 weeks. You need a good eye exam, and a temporary change in glasses may help in the interim.
Your diabetes doctor. Many people know that a rapid rise in sugar can cause blurred vision. The same thing can happen when sugar levels drop quickly. This is because sugar and water diffuse into and out of the lens more slowly than in other tissues. When the lens and the muscle that controls it have mismatched sugar levels, the lens stays the wrong shape, and things look blurry for a few weeks until it levels out.