How to manage a patient with impaired renal function on Lantus (insulin glargine) and prednisone, requiring additional insulin coverage, but refusing intensive management?

Management of Insulin Therapy for an Elderly Patient with Renal Impairment on Prednisone

For this 72-year-old male with impaired renal function (GFR 55) on prednisone who requires additional insulin but refuses BID NPH, correction scale, or carb counting, the most appropriate approach is to switch from Lantus to morning NPH insulin at 70% of his total daily insulin dose (approximately 17 units) to better match the hyperglycemic effect of prednisone.

Current Situation Assessment

• 72-year-old male with renal impairment (Cr 1.37, GFR 55) 1
• Currently on Lantus 13 units daily 1
• On prednisone 30 mg daily, causing significant hyperglycemia 2
• Required additional 12 units of Novolog to manage blood glucose 1
• Patient refuses twice-daily NPH, correction scale insulin, or carbohydrate counting 1

Why Current Regimen Is Inadequate

• Prednisone causes hyperglycemia predominantly between midday and midnight 2
• Lantus provides uniform insulin coverage throughout the day and night 1
• This mismatch between prednisone-induced hyperglycemia pattern and Lantus action profile requires additional prandial insulin 2
• The patient's renal impairment (GFR 55) requires careful insulin management to avoid hypoglycemia 3

Recommended Insulin Regimen

1. Switch from Lantus to morning NPH insulin 1, 4

   • NPH has a peak action that better matches prednisone-induced daytime hyperglycemia 2, 4
   • Administer in the morning to coincide with prednisone's hyperglycemic effect 1

2. Initial NPH dosing 1

   • Use 70% of total daily insulin dose (Lantus 13 units + Novolog 12 units = 25 units total) 1
   • Starting dose: approximately 17 units of NPH in the morning 1

3. Monitoring and adjustment 1, 5

   • Monitor blood glucose before lunch and dinner 1
   • Target glucose range: 90-150 mg/dL 1
   • Adjust NPH dose by 2 units every 3 days if 50% of readings are above target 1
   • Decrease dose by 2 units if experiencing hypoglycemia (<80 mg/dL) 1

Rationale for NPH Over Lantus

• Studies show NPH may be more effective than glargine (Lantus) for prednisone-induced hyperglycemia 4
• NPH's peak action (4-10 hours after injection) better matches the hyperglycemic effect of prednisone 2, 4
• Lower total daily insulin doses are typically needed with NPH compared to glargine in patients on prednisone 4
• Morning NPH administration provides coverage during the day when prednisone effect is strongest 2

Special Considerations for Renal Impairment

• Lower insulin doses are required with decreased GFR 1
• More frequent glucose monitoring is necessary to avoid hypoglycemia 3
• The patient's GFR of 55 ml/min requires careful insulin dose adjustment 3
• Risk of hypoglycemia and duration of insulin activity increases with impaired renal function 1

Avoiding Common Pitfalls

• Avoid relying solely on sliding scale insulin, which is strongly discouraged by guidelines 1, 5
• Do not mix insulin glargine (Lantus) with other insulins due to its acidic pH 1
• Avoid abrupt discontinuation of insulin therapy when transitioning between regimens 5
• Do not use rapid-acting insulin at bedtime to prevent nocturnal hypoglycemia 1

This approach simplifies the regimen to accommodate the patient's preferences while providing appropriate glycemic control for a patient with renal impairment on prednisone therapy.