Hello.
Since it was not healing for a year i would like to ask if there was any biopsy report of that fistula which was operated previously.
A recurrent fistula is common but needs to be evaluated before coming to a conclusion
Since you are a diabetic you should be cautious about
Chronic infections becoming florid or serious infections.
Some possibilities of recurrent fistula
Tuberculosis
Crohns disease
I would like you to
Next Steps
MRI fistulogram
proctoscopy/ sigmoidoscopy
visit a surgeon locally for biopsy of the tract
Health Tips
diabteic control
sitz bath
stool softner