You say you've got sugar, I assume you mean you have diabetes, probably type 2. Diabetics aren't supposed to use electric blankets because those who neglect their medications end up with nerve damage and can get burnt by an electric blanket and not realize it.
Having said that, I am a type 2 diabetic who does use an electric blanket because my bedroom is cold due to no insulation. I was sent to a nursing home to recover from cancer surgery and complained to a nurse about my legs always being cold. She spoke to a doctor and I was prescribed Gabapentin and was told it might take a week to get results. 3 nights later my legs felt fine at night. You need to talk to your doctor about your problem, you might be surprised by the results.