Going for surgery @ this age that too with
diabetes is not recommended.
Healing of post surgical wound becomes too delayed, in fact healing of fistula track is delaying because of diabetes.
Treatment of diabetes is not just making
sugar level readings normal, have to stop the pathology then healing will be faster.
If FBS reading is between 80 to 90 &
HbA1c between 6 to 7 its good.
Initiate a private chat to get better solution for your father's problem.