Diabetic in old ages

Patient: I am writing this for my father a 70 year old retired School teacher had diabetic for last 30 years. As he was controlling the diabetic through medication and his intensive diet, 2 year ago he badly affected with Chicken Gunia Virus and this made him very week. His palm and mussils were seriously melted after thishs has shivaring on his both arms. and he will not know if his slippers are off while walking.now he is taking insuline every day 1 unit (10)now he can walk slowly, but swelling on both legs , face,can you please suggest , what i can do to reduce sewlling