Thanks for your query.Based on the facts that you have posted it appears that you have fungal infection
of the foreskin.
Fungal infection of the foreskin is common amongst person with Diabetes
Please get your blood sugar levels done on empty stomach and post lunch to rule out Diabetes.If positive consult Diabetologist
or Physician for proper control of Diabetes.
Please take anti fungal medications like Fluconozole twice daily orally along with topical anti fungal jelly like Daskyl for application over foreskin twice daily.
Ensure to wash your genitals with warm water twice daily.It should get resolved within a week.