A Psychiatrist can you manage stress and depression. This is related with diabetes because being stressed is a complication of diabetes that i chose earlier. One you find a Psychiatrist you like he can help you to lower your stress and depression, to make it easier for diabetics.
A Nephrologist can help a diabetic with Kidney disease. Which is a complication of diabetes that occurs when you get high blood sugar, which cause your kidneys to work harder than they should. A Nephrologist would be helpful for a diabetic because they specialize in care for specific kidney problems that could be really useful for a diabetic.
When you have Diabetes you high glucose levels. A big part of being a healthy diabetic is having a good and balanced diet meal. A registered dietitian would be greatly helpful for a diabetic because they are trained to educate diabetics and help them set up and follow a daily meal plan for themselves.