What is the best approach to manage insulin in a patient with type 1 diabetes (T1D) who needs to be nothing by mouth (NPO) for a procedure?

Management of Insulin in Type 1 Diabetes Patients Who Are NPO for a Procedure

Continue basal insulin at 60-80% of the usual dose and monitor blood glucose every 4-6 hours while NPO, adding short- or rapid-acting insulin for correction as needed. 1

Critical Principle: Never Stop Basal Insulin

The most important rule in managing type 1 diabetes patients who are NPO is that basal insulin must never be completely discontinued 1, 2. Patients with type 1 diabetes lack endogenous insulin production, and stopping basal insulin—even when not eating—leads to rapid metabolic decompensation, hyperglycemia, and risk of diabetic ketoacidosis 1, 2.

Specific Dosing Algorithm

For Long-Acting Basal Insulin (Glargine/Lantus, Detemir/Levemir)

• Administer 60-80% of the patient's usual basal insulin dose on the morning of the procedure or the evening before 1, 2
• The American Diabetes Association specifically recommends giving half of the NPH dose or 60-80% of long-acting analog doses 1
• A recent study found that approximately 25% reduction in insulin dose the evening before surgery achieved better perioperative glucose control with less hypoglycemia 1

For Patients on Insulin Pumps

• For minor procedures: The pump may be continued if the patient can manage it autonomously and the procedure does not involve the abdomen 1
• For major surgery or abdominal procedures: Discontinue the pump and transition to intravenous insulin infusion at least 30 minutes before stopping the pump to prevent rapid hyperglycemia 1
• The 24-hour basal rate programmed in the pump provides an excellent guide for IV insulin requirements 1

Blood Glucose Monitoring Protocol

Monitor blood glucose every 4-6 hours while the patient remains NPO 1, 3, 2. This is the explicit recommendation from the American Diabetes Association Standards of Care 3.

• Do not extend monitoring intervals beyond 6 hours, even if glucose appears stable, as this increases risk of undetected hypoglycemia 3
• For patients on IV insulin infusion, monitor every 30 minutes to 2 hours 3

Correction Insulin Strategy

• Use short-acting (regular) or rapid-acting insulin (lispro, aspart, glulisine) for correction doses based on blood glucose monitoring results 1, 2
• Administer correction insulin as needed when blood glucose exceeds target range 1, 2
• The preferred regimen is basal plus correction insulin for NPO patients 1, 2

Target Glucose Range

Maintain blood glucose between 80-180 mg/dL (4.4-10.0 mmol/L) during the perioperative period 1. Tighter glycemic control does not improve outcomes and increases hypoglycemia risk 1.

Common Pitfalls to Avoid

• Never use sliding scale insulin alone without basal coverage 1, 2. This reactive approach is strongly discouraged and leads to poor glycemic control with increased risk of both hyperglycemia and hypoglycemia 1, 4
• Do not withhold basal insulin completely when a patient becomes NPO, as this can lead to significant hyperglycemia and metabolic decompensation 1, 2
• Do not assume that because the patient is not eating, they don't need insulin 1. Type 1 diabetes patients require continuous basal insulin to prevent gluconeogenesis and ketogenesis regardless of nutritional intake 1, 4

Resuming Normal Insulin Regimen

• Once the patient can eat, resume the full basal-bolus insulin regimen 1
• Administer rapid-acting insulin immediately before or after meals, adjusting for carbohydrate content 1
• If transitioning from IV insulin, continue the IV infusion for 2 hours after restarting subcutaneous basal insulin to establish adequate subcutaneous depot 1