What are your instructions to a type1 diabetic in regards to their medication before they have surgery?

Several. Depending on type and length of surgery, i generally advise my patients to reduce their Insulin dose the night before by a certain percentage and to allow IV fluids during the operation to have dextrose as aesthetic agents can cause hypoglycemia. Close bs monitoring also needed during the first 8-12hrs.
Basal insulin. Theycan stop taking their bolus / meal or short acting Insulin but continuetheir long acting or basal insulin.