What to do about extremely itchy rash caused by diabetes?

See your doctor: Diabetes is a small vessel disorder and the itch is not the classic allergic itch. One thing to do is to use a hypoallergenic lotion as much as you can since the most common cause of itchy skin is dry skin.

Many possibilities: There are many things that could cause a skin rash. Several types of inflammatory conditions of the skin, allergic reactions, sun exposure, insect bites, and sometimes bacterial, viral or fungal infections can cause rashes on the skin. Have it evaluated by a professional and get the appropriate treatment.