How long can a diabetic coma last? When a person comes out of it, is it possible to have amnesia?

I think it really depends on the cause of “diabetic coma.” This is not really a good, descriptive term. The loss of consciousness that comes from severe hypoglycemia usually does not last long, but if low enough, the brain could be without fuel long enough to cause brain injury and even with later correction of the blood glucose, still be associated with a “coma.” That scenario could lead to a prolonged coma, and the brain injury I am sure could lead to memory problems and others.

Extremely high blood sugars with or without DKA [diabetic ketoacidosis] can lead to brain swelling which can cause brain injury, coma and presumably injury to lead to memory or other problems. That type of coma, I think, has a better possibility of lasting longer and causing more injury than low blood glucose.

So, without understanding the circumstances that lead to your question, this is the general answer that I can provide.

DS