heart and diabetes existing) woul would the person that died not feel it and just like leave in their
sleep and does it cause the person to turn blue ?? Lack of blood ? hopefully not painful

i dont believe the person would feel anything but just be asleep. the person can become blue due to lack of oxygen.

It depends, every case it's different.

Remember actor Heath Ledger? He accidentally overdosed himself with too much medication (6 different medications not prescribed to him) he then went to sleep; later he was found on the floor in his bedroom, that means that he woke up most likely in pain, short of breath, scared and trying to get help...a very sad way to die.

Besides nobody have come from death to tell us if it was painless or not, so people is just really guessing.