Hi there...reddness and scaling over the glans penis is usually balanoposthitis which could have super added candida infection. First and foremost do not use any soaps or antiseptics solutions like dettol, savlon to wash your genitals. Use only lukewarm water with little salt in it. Also you will have to checked for diabetes, as it very common in diabetics and can be chronic. Ask your wife if she has any white discharge. Then she will have to also be treated. Kindly consult a dermatologist for further evaluation and treatment. You will probably be given oral and topical antifungal.