Thanks for your query.You are known diabetic and on oral anti diabetic medication.You are facing a problem of delayed erection .Diabetes
is one of the main known reasons for erectile dysfunction
.Have you checked your Blood sugar Levels frequently to asses whether your diabetes is under control or not.Please get it checked frequently. Practice some yoga
Do some moderate exercise and spent more time in arousal All these things will help you in achieving good erection and improve quality of sperm.