After my Dad passed away, Mom pretty much gave up. She won't help me with anything even though I've asked her to. She also doesn't help financialy other than maybe chip in when we eat out. I get very frustrated with her when it's time to go somewhere because she doesn't remember to or doesn't want to get ready to go. I can tell her 3 times to get ready and she still sits there. We've been late to appts. for this reason. I feel like I'm yelling at her all the time to do things but she won't listen. I need help dealing with her. I feel like she does things to antagonize me, but I'm sure it's just her diabetes and dimentia. Suggestions? She also doesn't want to take showers. She will do sponge baths but not showers. I feel like we argue all the time.
So my first question would be, what else is going on with your mother medically, besides diabetes. I imagine she sees her doctor at least quarterly (unless her blood sugars are very stable, and then it would be less often). When is her next appointment? I suggest contacting her doctor in advance and explain your concerns. Even if the doctor is a diabetes specialist and can't address other issues, he or she may be willing to refer her to someone else.
No, it is not "normal" to sit around and do nothing. Try to find out what is behind this change in behavior.
(By the way, did your dad pass away last month or four years ago?)