My little brother just got diagnosed literally 2 hours ago.

My little brother just got diagnosed with this condition literally 2 and a bit hours ago, it’s type 1 and we found out due to him being extremely thirsty and drinking a load of water. He’s just been so unlucky, with his autism and his epilepsy. He’s 11, nearly 12 and is there anything I need to know health-wise, like in case I’m alone with him and something happens? Thanks! :) -Sincerely, a concerned big bro!