My granpa 90 years old the blood sugar became 900 we took him to the hospital and he is 400 now but still tierd and cannot talkis he ok now or will die ?

Let Doctors handle..: Person, age unstated says My grandpa 90years blood sugar became 900 we took him to hospital and he is 400now but still tired and cannot talk is he ok now or will die? Very high Blood Sugar above 200 can be dangerous to health with thirst, frequent urination, blurry vision, fatigue/extreme tiredness. May lead to the state of Ketoacidosis; nausea, vomiting, difficulty breathing, even Coma. Let Docto