Basal insulin / NPH / insulin pumps
Insulin requires an individual perioperative plan. Type 1 diabetes requires ongoing basal insulin coverage even during fasting. A blanket instruction to stop all insulin is unsafe, and omission of basal insulin in type 1 diabetes can precipitate ketoacidosis.
What the plan needs to cover
The perioperative plan needs to address the regimen, dose timing, monitoring and correction of glucose levels before surgery. Basal analogues, NPH, mixed insulin and pumps require different approaches.
Renal impairment, previous hypoglycaemia, usual dose, fasting duration and procedure timing affect the plan.
The ADA guidance describes regimen-specific dose reductions, rather than a single rule to omit insulin. The size and timing of an adjustment depend on the insulin preparation, diabetes type, usual control and hypoglycaemia risk. The full guidance and institutional protocol are needed to prescribe the actual dose; this page is not a dosing chart.
Monitoring and targets
The ADA describes a perioperative blood glucose target of 100–180 mg/dL (5.6–10.0 mmol/L), with individual adjustment where appropriate. Recent glycaemic control can inform preparation, but an HbA1c value alone is not a universal pass/fail threshold for surgery. CGM is not used as the sole intraoperative glucose measurement. A local plan typically addresses:
- Monitoring frequency before, during and after surgery
- Correction insulin thresholds
- Hypoglycaemia treatment compatible with fasting status
- Criteria for variable-rate intravenous insulin infusion
Insulin pumps
Pump continuation depends on the procedure and institutional support. ADA 2026 states that pump use may continue during surgery where consistent with institutional policy, with an interprofessional approach, and that an alternative plan (insulin infusion or basal plus correction insulin) should be started before surgery if the pump cannot be used. Factors usually considered include:
- Expected procedure duration and haemodynamic stability
- Whether the patient will be able to manage the pump, or whether staff trained in pump management are available
- Access to the infusion site and its distance from the surgical field and electrosurgical equipment
- Imaging requirements
When a pump cannot continue, alternative insulin delivery is needed before interruption.
Practical application
- Early scheduling, where feasible, may reduce disruption to the usual insulin and meal schedule.
- Written, regimen-specific instructions can distinguish the evening-before and morning-of-surgery doses.
- The patient’s glucose meter, monitor details and insulin supplies may be useful, depending on hospital policy.
- The transition back to the usual regimen depends on recovery, nutritional intake and glucose control.