hi robin, penile skin issues are common in diabetics. good local hygeine and regular inspection is needed. drying of foreskin occurs, when one tries to retract the foreskin, there can be small cracks which heal and cause further narrowing, eventually foreskin cannot be retracted (phimosis). this requires circumcision
(removal of foreskin). get checked by a urologist
to rule out skin infection
(commonly fungal) and whether you need circumcision. donot apply antiseptics. clean with warm water, dry and apply bland cream like nivea. take care.