What adjustments should be made to a 72-year-old male's diabetes regimen, currently on metformin (Metformin) 1500 mg, prednisone (Prednisone) 30 mg daily, and NPH (Neutral Protamine Hagedorn) insulin 17 units, requiring an additional 12 units, who refuses to engage in correction or carb counting?

Insulin Regimen Adjustment for Elderly Patient on Prednisone

For a 72-year-old male on metformin 1500 mg, prednisone 30 mg daily, and NPH insulin 17 units requiring an additional 12 units who refuses correction or carb counting, the most appropriate approach is to switch to a morning-only NPH insulin regimen using 70% of his total daily insulin dose (approximately 20 units) with scheduled dose adjustments based on fasting glucose patterns.

Understanding the Current Situation

• The patient is currently on:

  • Metformin 1500 mg daily
  • Prednisone 30 mg daily
  • NPH insulin 17 units
  • Requiring an additional 12 units (suggesting inadequate control)
  • Patient refuses correction insulin or carbohydrate counting 1

• Key considerations in this case:

  • Advanced age (72 years) requires special attention to medication management 1
  • Prednisone therapy significantly affects glycemic control, causing disproportionate hyperglycemia during the day 1
  • Patient's preference against complex insulin regimens must be respected 1

Recommended Insulin Regimen Adjustment

Step 1: Simplify the Insulin Regimen

• Change from current regimen to a simplified morning-only NPH insulin regimen 1
• Calculate new dose:
  • Current total daily insulin = 17 units (basal) + 12 units (additional) = 29 units
  • Use 70% of total daily dose = approximately 20 units of NPH insulin 1
  • Administer as a single morning dose 1

Step 2: Titration Protocol

• Monitor fasting blood glucose daily 1
• Target fasting glucose range: 90-150 mg/dL (5.0-8.3 mmol/L) 1
• Adjust dose based on patterns:
  • If 50% of fasting glucose values are above target: increase dose by 2 units 1
  • If >2 fasting glucose values/week are <80 mg/dL: decrease dose by 2 units 1

Step 3: Address Prednisone-Induced Hyperglycemia

• Morning-administered NPH insulin is particularly appropriate for patients on morning prednisone regimens 1
• NPH's intermediate-acting profile helps counter the afternoon/evening hyperglycemia commonly seen with prednisone therapy 1
• The peak action of NPH (4-10 hours after injection) aligns well with prednisone's peak hyperglycemic effect 2

Rationale for This Approach

• Simplification is appropriate for older adults to reduce treatment burden while maintaining adequate glycemic control 1
• Morning administration of NPH insulin better matches the glucose profile induced by morning prednisone doses 1
• Single daily injection improves adherence and reduces risk of medication errors in older adults 1
• Maintaining metformin is appropriate as it remains effective as a first-line agent for older adults with adequate renal function 1, 3

Important Considerations and Monitoring

• Continue metformin as long as estimated GFR remains ≥30 mL/min/1.73m² 1
• Monitor for gastrointestinal side effects from metformin that may be problematic in older adults 1
• Evaluate renal function regularly, as both age and potential diabetes complications may affect kidney function 1
• Be vigilant for hypoglycemia, especially if prednisone dose is reduced 1
• Avoid rapid-acting or short-acting insulin at bedtime to prevent nocturnal hypoglycemia 1

Common Pitfalls to Avoid

• Do not use complex sliding scale regimens since the patient refuses correction insulin 1
• Avoid bedtime NPH insulin in older adults due to increased risk of nocturnal hypoglycemia 1
• Do not abruptly discontinue metformin unless contraindicated by renal function or other factors 1
• Remember that glucocorticoid-induced hyperglycemia requires special consideration in insulin dosing 1
• Avoid using premixed insulins which may be too complex for this patient's preferences 1

By following this simplified approach, the patient's glycemic control can be improved while respecting his preference against complex insulin regimens and accounting for the effects of prednisone therapy on blood glucose patterns.