In an adult with type 2 diabetes taking insulin glargine (Lantus) 16 units daily who will be NPO starting at midnight, how should the basal insulin be managed and what glucose monitoring is recommended?

Management of Basal Insulin in a Type 2 Diabetes Patient Who Will Be NPO at Midnight

Continue Lantus 16 units at the usual time (typically bedtime) on the evening before the procedure, but reduce the dose by approximately 25% to 12 units to minimize hypoglycemia risk while maintaining basal glucose control. 1

Basal Insulin Management Strategy

Pre-Procedure Evening Dose

• Administer 75-80% of the usual basal insulin dose (12-13 units instead of 16 units) on the evening before surgery to achieve target glucose levels with decreased hypoglycemia risk 1
• The dose reduction accounts for the absence of overnight and morning food intake while still providing essential basal coverage to prevent hyperglycemia 1
• Basal insulin should never be completely withheld in patients with diabetes, even when NPO, as it controls hepatic glucose production independent of food intake 2, 1

Timing Considerations

• If the patient normally takes Lantus at bedtime (20:00 or later), administer the reduced dose at the usual time 1
• Lantus provides relatively constant basal insulin coverage for approximately 24 hours without significant peaks, making it suitable for NPO periods 3, 4

Glucose Monitoring Protocol

Monitoring Frequency

• Check capillary blood glucose every 2-4 hours while the patient is NPO peri-operatively 1
• Measure glucose on arrival to the facility before any procedure 2
• Continue monitoring until oral intake resumes 2

Target Glucose Range

• Aim for peri-operative glucose of 80-180 mg/dL 1
• For ambulatory/same-day procedures, target 90-180 mg/dL (5-10 mmol/L) 2

Correction Insulin Protocol

When to Administer Correction Doses

• If glucose exceeds 180 mg/dL, administer correction doses of rapid-acting insulin (e.g., lispro, aspart) 1
• Use 2 units of rapid-acting insulin for glucose >250 mg/dL 1
• Use 4 units of rapid-acting insulin for glucose >350 mg/dL 1

Hypoglycemia Management

• Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate if the patient is awake and able to take oral intake 1
• If the patient cannot take oral intake and glucose drops below 70 mg/dL, administer intravenous dextrose (typically D10W at 40 mL/hour or D5W at higher rates) 2
• If hypoglycemia occurs, the basal insulin dose was likely too high and should be reduced by 10-20% for future procedures 1

Resumption of Normal Regimen

When Oral Intake Resumes

• Once the patient can eat normally, resume the full usual dose of Lantus 16 units at the regular scheduled time 2
• If the patient leaves recovery before 10:00 AM and can eat breakfast, serve the meal and have the patient take morning medications at that time 2
• If discharge occurs between 10:00 AM and noon, provide a light meal and resume usual medications 2

Post-Procedure Monitoring

• Continue measuring capillary blood glucose before meals and at bedtime until stable 2
• If glucose remains >180 mg/dL (10 mmol/L) after resuming oral intake, the patient should remain under observation and receive correction insulin until glucose decreases to 90-180 mg/dL 2
• If glucose exceeds 300 mg/dL (16.5 mmol/L) post-procedure, consider hospital admission for closer monitoring 2

Foundation Therapy Considerations

• Continue metformin unless specifically contraindicated (e.g., contrast dye administration, renal impairment, or prolonged NPO status) 2
• Metformin can typically be resumed once oral intake is established and renal function is stable 2
• Hold sulfonylureas on the day of the procedure due to hypoglycemia risk when NPO 2

Critical Pitfalls to Avoid

• Never completely withhold basal insulin in a patient who will be NPO—this leads to uncontrolled hyperglycemia and potential ketosis 2, 1
• Do not rely solely on sliding-scale correction insulin without basal coverage, as this approach is condemned by all major diabetes guidelines and leads to dangerous glucose fluctuations 1
• Avoid giving rapid-acting insulin at bedtime as a sole correction dose, which markedly increases nocturnal hypoglycemia risk 1
• Do not use the full usual basal dose without reduction when the patient will miss meals, as this significantly increases hypoglycemia risk 1

Special Considerations for Extended NPO Periods

• If NPO status extends beyond 12-24 hours or the patient has poor oral intake post-procedure, consider reducing basal insulin further to 0.1-0.15 units/kg/day (approximately 7-10 units for a typical adult) 1
• For prolonged NPO periods, check glucose every 4-6 hours rather than every 2-4 hours 1
• Maintain intravenous dextrose infusion (D5W or D10W) if NPO status is prolonged to prevent hypoglycemia while providing minimal basal insulin 2