My Husband Is A Type 1.5 Diabetic. He Just Went

My husband is a type 1.5 diabetic. He just went on an insulin pump. His recent blood work showed that his kidney function was borderline. I'm a bit concerned. Should he be drinking a certain amount of water each day. Some days he has very little fluids. I am a firm believer in drinking 8 glasses of water each day. Should I be concerned?