What insulin dose adjustments are recommended for a 47-year-old type 2 diabetes patient on Lantus (insulin glargine) 55 units who will be NPO (nothing by mouth) at midnight and has undergone multiple tooth extractions?

Perioperative Insulin Management for NPO Patient After Dental Extraction

Reduce the Lantus dose to approximately 41 units (75% of usual 55 units) the evening before the procedure, monitor blood glucose every 2-4 hours while NPO, and use rapid-acting insulin for correction doses if glucose exceeds 180 mg/dL. 1

Basal Insulin Dose Adjustment

The most critical intervention is reducing the evening basal insulin dose by 25% the night before the procedure. 1, 2

• Give 41 units of Lantus (75% of the usual 55 units) at the patient's usual evening administration time 1
• This 25% reduction is specifically recommended by the American Diabetes Association to achieve perioperative blood glucose goals with lower hypoglycemia risk 1, 2
• Do NOT discontinue the basal insulin entirely - this leads to hyperglycemia and worse perioperative outcomes 2

Blood Glucose Monitoring Protocol

Monitor blood glucose every 2-4 hours throughout the NPO period, with particular attention overnight when hypoglycemia risk peaks. 1, 2

• The 2-4 hour monitoring interval is explicitly recommended by the American Diabetes Association for NPO patients 1, 2
• Overnight monitoring is especially critical as 78% of hypoglycemic episodes occur during nighttime hours in patients on basal insulin 2

Target Blood Glucose Range

Maintain perioperative blood glucose between 100-180 mg/dL. 1, 2

• Stricter targets (tighter than 80-180 mg/dL) do not improve outcomes and increase hypoglycemia risk 1
• This target should be achieved within 4 hours of the procedure 1

Correction Insulin Protocol

Administer short- or rapid-acting insulin for correction when blood glucose exceeds 180 mg/dL. 1, 2

• Use rapid-acting insulin (lispro, aspart, or glulisine) or regular insulin for corrections 1, 2
• Continue basal insulin coverage even while NPO - the correction insulin addresses hyperglycemia while basal insulin prevents ketosis 2

Dextrose Infusion Considerations

Dextrose infusion (D5) is NOT routinely necessary but should be initiated if hypoglycemia occurs or blood glucose falls below 70 mg/dL. 2

• Start D5 infusion if glucose is trending downward despite the reduced basal insulin dose 2
• The 25% dose reduction typically prevents the need for routine dextrose supplementation 2

Post-Procedure Considerations for Dental Extraction

The patient may have difficulty eating after multiple tooth extractions, requiring continued monitoring and potential further insulin adjustments. 1

• If the patient cannot resume normal oral intake, continue monitoring every 2-4 hours 1
• Consider liquid nutritional supplements if solid food intake is limited
• Adjust insulin doses based on actual carbohydrate intake once eating resumes

Critical Pitfalls to Avoid

The most dangerous error is failing to reduce the basal insulin dose the evening before the procedure - this significantly increases overnight hypoglycemia risk. 2

• Another common mistake is completely stopping basal insulin while NPO, which leads to hyperglycemia and metabolic decompensation 2
• Do not use continuous glucose monitoring (CGM) alone for perioperative glucose monitoring - point-of-care testing is required 1
• Metformin should be held on the day of surgery if the patient is taking it 1