Sis in law in coma for five days?

My sis in law went to hospital for low electrolytes. She was doing well. On the 4th day in hospital they had checked her vitals at 3 in the morning and she was up watching tv, communicating and doing quite well. At 4 a.m. she was unresponsive and is now 5 days into coma. The doc says that the medicine they had given her was all glucose based and when they did sugar test was over 1200 because of this but he does not admit that this is what caused the coma. Her MRI showed her brain was normal but she is completely unresponsive. She is on a ventilator and they are talking about putting in a trach. Her hands are balled into fists. They cannot or will not tell us what exactly is causing this or what the prognosis will be. Can anyone help?