How do you manage blood glucose levels in a patient with Maturity-Onset Diabetes of the Young (MODY) who is Nil Per Os (NPO) for an upcoming operation?

Management of MODY Patients Who Are NPO for Surgery

For patients with Maturity-Onset Diabetes of the Young (MODY) who are NPO for surgery, maintain blood glucose between 100-180 mg/dL (5.6-10.0 mmol/L) by continuing basal insulin at 60-80% of usual dose and monitoring glucose every 2-4 hours with correction doses of short-acting insulin as needed.

Understanding MODY in the Perioperative Setting

MODY is a monogenic form of diabetes with several subtypes that require different management approaches:

• Different from both Type 1 and Type 2 diabetes
• Autosomal dominant inheritance pattern
• Early onset with absence of pancreatic islet autoimmunity 1
• Treatment needs vary by subtype:
  • GCK-MODY (MODY2): Often requires no treatment
  • HNF1A-MODY (MODY3) and HNF4A-MODY (MODY1): May be responsive to oral agents 2

Preoperative Assessment

1. Evaluate recent glycemic control:

   • Target A1C <8% for elective surgeries 3
   • Review recent blood glucose values and patterns
   • Identify any recent episodes of hypoglycemia or hyperglycemia 3

2. Medication adjustments day of surgery:

   • Withhold metformin on the day of surgery 3
   • Withhold SGLT2 inhibitors 3-4 days before surgery 3
   • Withhold all other oral hypoglycemic agents the morning of surgery 3

Intraoperative and NPO Management Algorithm

For MODY patients on insulin:

1. Basal insulin adjustment:

   • Give 60-80% of usual long-acting insulin analog dose 3
   • If on NPH insulin, give half of the usual dose 3
   • If using insulin pump, remove pump and transition to IV insulin 3

2. Blood glucose monitoring:

   • Monitor blood glucose every 2-4 hours while NPO 3
   • Use arterial or venous blood samples rather than capillary readings when possible 3
   • Target range: 100-180 mg/dL (5.6-10.0 mmol/L) 3

3. Correction insulin:

   • Use short-acting or rapid-acting insulin for correction doses 3
   • Avoid tight glycemic control (<80 mg/dL) as it increases hypoglycemia risk without improving outcomes 3

For MODY patients not on insulin:

1. Monitor blood glucose every 2-4 hours
2. Initiate correction insulin if glucose exceeds 180 mg/dL
3. Consider IV insulin infusion for persistent hyperglycemia

IV Insulin Protocol for Significant Hyperglycemia

If blood glucose remains >180 mg/dL despite correction doses or if the patient has Type 1 MODY variants:

1. Start IV insulin infusion with glucose administration:

   • Administer IV glucose equivalent to 4 g/hour 3
   • Monitor potassium levels every 4 hours to avoid insulin-induced hypokalemia 3

2. Target blood glucose range of 90-180 mg/dL (5-10 mmol/L) 3

Common Pitfalls and How to Avoid Them

1. Avoid "hold-the-insulin" routines:

   • Never completely withhold insulin in insulin-dependent MODY subtypes 4
   • Basal insulin needs continue even when NPO

2. Prevent hypoglycemia:

   • A 25% reduction in evening insulin before surgery reduces hypoglycemia risk 3
   • Any unexplained malaise should be considered potential hypoglycemia 3
   • Define hypoglycemia as <70 mg/dL (3.9 mmol/L) and treat promptly 3

3. Avoid excessive hyperglycemia:

   • Hyperglycemia >180 mg/dL increases infection risk and complications 5
   • Basal-bolus insulin regimens are superior to sliding scale alone 3

4. Recognize subtype-specific considerations:

   • GCK-MODY (MODY2) patients may require minimal intervention
   • HNF1A-MODY (MODY3) and HNF4A-MODY (MODY1) patients will likely need more aggressive management

Resuming Oral Intake

When oral intake resumes:

• Return to pre-surgical insulin regimen with appropriate dose adjustments
• Resume oral medications according to renal function and clinical status
• Continue monitoring blood glucose closely during transition

By following this structured approach to managing MODY patients who are NPO for surgery, you can minimize the risks of both hyperglycemia and hypoglycemia while optimizing perioperative outcomes.