Can I add Basaglar (insulin glargine) and Humalog (insulin lispro) to a patient's regimen of metformin and glipizide (glyburide) if their Hemoglobin A1c (HbA1c) is still elevated?

Adding Insulin to Metformin and Glipizide for Elevated HbA1c

Yes, you can add Basaglar (insulin glargine) and Humalog (insulin lispro) to a patient's regimen of metformin and glipizide when their HbA1c remains elevated, starting with Basaglar at 10 units daily or 0.1-0.2 units/kg/day and Humalog at 4 units or 10% of the basal dose before meals.

When to Add Insulin

When a patient on metformin and sulfonylurea (like glipizide) therapy has an elevated HbA1c despite optimized oral therapy, progression to insulin therapy is appropriate and recommended by guidelines 1. This progression follows the natural history of type 2 diabetes, where beta cell function progressively declines over time.

Starting with Basal Insulin (Basaglar)

1. Initial dosing:

   • Start Basaglar (insulin glargine) at 10 units per day or 0.1-0.2 units/kg/day 1
   • Administer once daily at the same time each day

2. Titration:

   • Adjust dose by 2-4 units every 3-4 days based on fasting blood glucose levels
   • Target fasting glucose of 80-130 mg/dL
   • Continue until fasting glucose targets are achieved or dose exceeds 0.5 units/kg/day

3. Medication adjustments:

   • Continue metformin at the current dose 1
   • Consider maintaining glipizide initially, but be prepared to reduce the dose or discontinue if hypoglycemia occurs 1, 2

Adding Mealtime Insulin (Humalog)

If HbA1c remains elevated despite optimized basal insulin (Basaglar):

1. Initial dosing:

   • Start Humalog (insulin lispro) at 4 units, 0.1 units/kg, or 10% of the basal insulin dose before meals 1
   • Begin with the largest meal of the day first, then add to other meals if needed

2. Titration:

   • Adjust by 1-2 units every 3-4 days based on 2-hour postprandial glucose values
   • Target postprandial glucose <180 mg/dL

3. Medication adjustments:

   • Continue metformin 1
   • Consider discontinuing glipizide when using multiple daily injections of insulin to reduce hypoglycemia risk 1

Monitoring and Safety Considerations

1. Hypoglycemia risk:

   • The combination of sulfonylureas (glipizide) with insulin significantly increases hypoglycemia risk 2
   • Monitor blood glucose closely, especially during initial titration
   • Educate patient on hypoglycemia recognition and treatment

2. Weight considerations:

   • Both insulin and sulfonylureas can cause weight gain 1
   • Maintaining metformin can help mitigate some weight gain

3. Blood glucose monitoring:

   • Require frequent self-monitoring of blood glucose
   • Check fasting glucose daily for basal insulin adjustment
   • Check pre-meal and 2-hour post-meal glucose for mealtime insulin adjustment

Alternative Approaches to Consider

Before advancing to a full basal-bolus insulin regimen, consider these intermediate steps if appropriate:

1. Basal insulin plus single mealtime injection:

   • Add Humalog only before the largest meal initially 1
   • This simplified approach may improve adherence while addressing postprandial hyperglycemia

2. GLP-1 receptor agonist plus basal insulin:

   • Consider adding a GLP-1 receptor agonist instead of mealtime insulin 1, 3
   • This combination provides similar glycemic control with less hypoglycemia and weight gain

Key Pitfalls to Avoid

1. Inadequate dose titration: Failure to aggressively titrate insulin doses is a common cause of continued poor glycemic control.

2. Maintaining sulfonylureas with multiple insulin injections: This increases hypoglycemia risk without significant benefit once on a basal-bolus regimen.

3. Insufficient patient education: Ensure the patient understands insulin administration, glucose monitoring, and hypoglycemia management.

4. Ignoring lifestyle factors: Reinforce consistent meal timing and carbohydrate content to match insulin dosing.