I Think My Husband May Have Diabetes, Kindly Advice Me

He s showing the classic symtoms of going to the toilet more often, drinking loads, pains in his chest , feeling weak and then fine after a meal . He won t go to the doctor . What can I do? He had an illness last year called labyrinthitus, mainly the same symtoms but was given tablets from the doctor but they don t seem to work very well. Hes very overwieght but refuses point blank to eat ANY fruit or veg, with the exception of potatoes. I am really struggling here, so any serious answers would be greatly appreciated.