Lantus Dose Adjustment for NPO Patients
For patients who are NPO prior to surgery, reduce the Lantus (insulin glargine) dose to 60-80% of the usual dose, with the most recent evidence supporting a 75-80% dose (or approximately 25% reduction) given the evening before surgery. 1, 2
Specific Dosing Algorithm
Evening Before Surgery
- Administer 75-80% of the patient's usual long-acting insulin analog dose the night before the procedure 2
- This 20-25% reduction achieves perioperative blood glucose targets while significantly decreasing hypoglycemia risk, particularly during overnight hours when 78% of hypoglycemic episodes occur 2
- The American Diabetes Association guidelines specify giving "60-80% doses of a long-acting analog" for NPO patients 1
Blood Glucose Monitoring While NPO
- Monitor blood glucose every 2-4 hours while the patient remains NPO 2
- Earlier guidelines recommended every 4-6 hours 1, but current recommendations have tightened this to every 2-4 hours for enhanced safety 2
- Increase monitoring frequency overnight when hypoglycemia risk peaks 2
Correction Insulin Protocol
- Continue basal insulin coverage even while NPO—never discontinue it entirely 2
- Add short-acting or rapid-acting insulin for correction doses when blood glucose exceeds 180 mg/dL 1, 2
- Target perioperative blood glucose range of 100-180 mg/dL to minimize both hypoglycemia and hyperglycemia 2
Dextrose Supplementation
- D5 infusion is NOT routinely required for all NPO patients on reduced basal insulin 2
- Start D5 infusion only if blood glucose falls below 70 mg/dL or trends downward despite the reduced basal dose 2
- Reserve dextrose for patients at high risk for hypoglycemia or those experiencing actual hypoglycemia 2
Critical Pitfalls to Avoid
Most Common Error
- Failing to reduce the basal insulin dose the evening before surgery is the most critical mistake, significantly increasing hypoglycemia risk 2
- This error is particularly dangerous because most hypoglycemic episodes occur overnight in the perioperative period 2
Second Most Common Error
- Discontinuing basal insulin entirely while NPO leads to hyperglycemia and worse perioperative outcomes 2
- Even NPO patients require basal insulin coverage to prevent hyperglycemic crises 2
Evidence Quality Note
The 20-25% dose reduction recommendation is supported by recent comparative data showing that this approach more effectively achieves target perioperative glucose levels with decreased hypoglycemia risk compared to giving the full usual dose 1. Tighter glycemic control (stricter than 80-180 mg/dL) does not improve outcomes and increases hypoglycemia 1.