What is the best approach to manage blood glucose levels in patients who are nil per os (NPO) due to aspiration risk and are not receiving insulin?

Management of NPO Patients Not on Insulin with Aspiration Risk

For diabetic patients who are NPO due to aspiration risk and not currently receiving insulin, preoperative glucose infusion is not necessary, and you should monitor blood glucose every 4-6 hours while withholding all oral antidiabetic medications except metformin (which should be stopped the evening before). 1

Medication Management Strategy

Oral Antidiabetic Agents

• Withhold all oral hypoglycemic agents on the morning of procedures or when NPO status begins to prevent hypoglycemia 2
• Stop sulfonylureas (like glipizide) immediately when the patient becomes NPO, as these carry the second-highest risk of hypoglycemia after insulin and should never be given to NPO patients 2
• Discontinue metformin from the evening before the NPO period begins 1
• Non-insulin drugs should not be administered on the morning of intervention 1

When Insulin Becomes Necessary

If blood glucose rises above 180 mg/dL while NPO, initiate correction insulin rather than restarting oral agents: 2

• Use short-acting (regular) insulin every 6 hours, OR
• Use rapid-acting insulin every 4 hours for correction doses 2
• Avoid sliding-scale insulin as the sole method - this reactive approach is strongly discouraged and can lead to both hyper- and hypoglycemia 1, 3

For patients with good metabolic control previously treated with oral agents at home, sliding scale insulin alone may be acceptable initially 1

• However, basal insulin may be required if glucose levels cannot be maintained below 180 mg/dL (10.0 mmol/L) 1

Monitoring Protocol

Blood Glucose Surveillance

• Monitor blood glucose every 4-6 hours minimum while NPO 3, 2
• Increase monitoring frequency to every 1-2 hours if:
  • Hypoglycemia has occurred 3
  • Glucose trends downward 2
  • Patient is on insulin infusion 3

Target Glucose Range

• Maintain blood glucose between 100-180 mg/dL (5.55-10.0 mmol/L) for NPO patients 1, 3
• A blood sugar level <180 g/L (10 mmol/L) before intervention decreases the risk of death, infection, and duration of stay 1

High-Risk Populations Requiring Increased Vigilance

Patients at highest risk for hypoglycemia while NPO include those with: 4

• Multisystem organ failure (41% of hypoglycemic events)
• Soft tissue infections
• Acute or chronic liver failure/cirrhosis
• Polytrauma

Critical Pitfalls to Avoid

Medication Errors

• Never give scheduled sulfonylureas to NPO patients - this is strongly discouraged due to high hypoglycemia risk 2
• Do not use sliding-scale sulfonylureas in any NPO patient 2
• Avoid premixed insulin therapy (70/30) as it is associated with unacceptably high rates of iatrogenic hypoglycemia 1

Management Errors

• Do not provide preoperative glucose infusion in non-insulin-treated patients - this is unnecessary 1
• Do not rely solely on sliding-scale insulin if insulin becomes necessary - add basal insulin if glucose cannot be controlled below 180 mg/dL 1
• Recognize that most hypoglycemic events (59%) in NPO patients are iatrogenic and preventable with appropriate medication adjustments 4

Special Considerations for Aspiration Risk

For patients with gastroparesis (common in diabetes and contributing to aspiration risk):

• This creates a risk of gastric content stasis and aspiration at induction of anesthesia 1
• Requires use of rapid sequence induction technique if anesthesia is needed 1
• The NPO status is particularly important in this population to minimize aspiration risk

Transition Planning

When oral intake resumes:

• Restart home oral antidiabetic medications once the patient is tolerating oral intake consistently
• If insulin was initiated during NPO period, reassess need for continuation based on glucose control
• Document all hypoglycemic episodes (if any occurred) to identify patterns and prevent recurrence 3