What is the best course of action to treat afternoon hyperglycemia in a patient on insulin degludec (insulin degludec) with afternoon blood glucose levels in the hyperglycemic range and morning blood glucose levels around 130 mg/dL?

Management of Afternoon Hyperglycemia in a Patient on Insulin Degludec

For a patient on insulin degludec 12 units with afternoon blood glucose levels of 300-400 mg/dL and morning levels around 130 mg/dL, the best course of action is to add prandial insulin before lunch to target the postprandial glucose excursion.

Understanding the Pattern

The patient's glucose pattern shows:

• Controlled morning blood glucose (~130 mg/dL)
• Significant afternoon hyperglycemia (300-400 mg/dL)

This pattern indicates:

• The basal insulin (degludec) is adequately controlling overnight and fasting glucose
• There is inadequate insulin coverage during daytime, particularly after meals

Treatment Algorithm

Step 1: Assess Basal Insulin Coverage

• Morning glucose of 130 mg/dL suggests adequate overnight basal coverage
• Current degludec dose (12 units) appears appropriate for fasting control
• No need to increase basal insulin as this could lead to nocturnal hypoglycemia

Step 2: Add Prandial Insulin

• Add rapid-acting insulin before lunch to target afternoon hyperglycemia 1
• Starting dose: 4 units or 10% of basal dose (approximately 1-2 units) 1
• Titration: Increase by 1-2 units or 10-15% twice weekly until target achieved 1

Step 3: Monitoring and Adjustment

• Monitor blood glucose before and 2 hours after lunch
• Target postprandial glucose: <180 mg/dL 2
• Adjust prandial insulin dose based on postprandial readings
• For hypoglycemia: determine cause; if no clear reason, lower dose by 10-20% 1

Evidence-Based Rationale

The American Diabetes Association guidelines specifically recommend adding prandial insulin when significant postprandial glucose excursions occur (>180 mg/dL) despite adequate fasting glucose control 1. This approach is supported by the "graduated approach" recommended in guidelines, which suggests adding prandial insulin before the meal responsible for the largest glucose excursion 1.

Insulin degludec is an ultra-long-acting basal insulin with a steady-state profile characterized by a near-constant effect 3. Its primary role is controlling fasting glucose, which appears adequate in this patient. Adding prandial insulin is the appropriate next step rather than increasing basal insulin, which could lead to overnight hypoglycemia without adequately addressing the afternoon hyperglycemia 1.

Important Considerations

• Avoid overbasalization: Increasing basal insulin beyond 0.5 units/kg/day often leads to hypoglycemia without addressing postprandial excursions 1, 2
• Meal timing: Ensure the patient is eating consistently timed meals
• Carbohydrate counting: Consider teaching the patient to adjust prandial insulin based on carbohydrate intake
• Hypoglycemia risk: Monitor for and educate about signs, symptoms, and treatment of hypoglycemia
• Alternative approach: If the patient is resistant to multiple daily injections, consider switching to premixed insulin (such as 70/30 degludec/aspart mix) taken before breakfast and dinner 1

By targeting the specific time of hyperglycemia with prandial insulin rather than increasing basal insulin, this approach addresses the underlying problem while minimizing the risk of nocturnal hypoglycemia.