Hello,  Up to one third of people with diabetes will experience skin problems related to the disease. If caught early, most conditions can be treated and resolved. Although the most common skin infections in a diabetic are bacterial infections and fungal infections but since you are not complaining of any itching or pain,they seem to be ruled out. Other important skin conditions which don t cause any pain or itching are.. Diabetic dermopathy  Diabetic blisters called as bullosis diabeticorum etc. I would advise you to consult a dermatologist for the proper diagnosis of cause. In general the treatment for such conditions is meticulous control of blood sugar levels. Thanks