My Brother Was 2 Days With Diabetic Coma Unattended, By

My brother was 2 days with diabetic coma unattended, by the third day he was taken to the hospital now he is still in coma for 5 days. What Chances does he has of severe brain damage? Will he wake up? He seems stable. Also he is alcoholic. He was drinking before the coma. He is 36 years