hello, you have written you are diabetic ,it means u aye more prone for infection and other complication of diabetes
.the one of the commenest cause or red patch in penis is balanoposthitis
.most common etiology is diabetes and candidal infection ,so if you are complaining itching ,no history of sexual exposure,creamy discharge ,the diagnosis goes towards balanoposthitis. and the treatment is take.
tab (200mg)single tablet
cream) or low-potency steroid creams apply locally twice daily
3)proper sanitation of affected area
4) control of blood sugar is necessary