What is the typical dosing regimen for NPH (Neutral Protamine Hagedorn) intermediate-acting insulin?

NPH Insulin Dosing Regimen

The typical dosing regimen for NPH (Neutral Protamine Hagedorn) insulin is to start with 10 units per day or 0.1-0.2 units/kg per day, with subsequent adjustments of 2 units every 3 days based on fasting blood glucose monitoring until target range is achieved. 1, 2

Initial Dosing

• Start with 10 units per day OR 0.1-0.2 units/kg per day 1
• For insulin-naive patients, consider starting at the lower end of the range (0.1-0.2 units/kg/day) 2
• Total daily insulin requirement typically ranges from 0.4-1.0 units/kg/day for most patients 2

Administration Schedule

NPH insulin can be administered in different schedules depending on glycemic control needs:

Once-daily regimen:

• Typically administered at bedtime
• Useful when initiating insulin in type 2 diabetes patients previously on oral agents 1

Twice-daily regimen:

• Morning and bedtime dosing
• When converting from once-daily to twice-daily NPH:
  • Total dose = 80% of current bedtime NPH dose
  • 2/3 given in the morning, 1/3 given at bedtime 1
• More effective for controlling glucose throughout the day 1

Special situations:

• For patients on glucocorticoid therapy: NPH insulin is particularly useful as its peak action (4-6 hours) aligns with the peak glucose-raising effect of intermediate-acting steroids like prednisone 1
• For enteral/parenteral nutrition: NPH can be given every 8-12 hours to cover nutritional requirements 1

Dose Titration

• Set fasting plasma glucose (FPG) target (typically 90-150 mg/dL) 1, 2
• Increase dose by 2 units every 3 days until FPG target is reached without hypoglycemia 1, 2
• If hypoglycemia occurs, determine the cause; if no clear reason, lower dose by 10-20% 1
• For older adults, consider less stringent targets (90-150 mg/dL) to reduce hypoglycemia risk 2

Combination Therapy

• NPH can be used alone or in combination with:
  • Oral antidiabetic agents (particularly metformin) 3, 4
  • Prandial insulin (regular or rapid-acting analogs) 1
• When adding prandial insulin to NPH:
  • Start with 4 units per day or 10% of basal dose 1
  • Consider reducing NPH dose by 10% if A1C <8% 1
  • Increase prandial dose by 1-2 units or 10-15% twice weekly 1

Monitoring

• Check blood glucose before breakfast daily during titration 2
• Additional checks before lunch and dinner may help assess 24-hour control 2
• Monitor for hypoglycemia, especially during the first 12 weeks of therapy 4

Clinical Considerations

• NPH has an intermediate duration of action with onset at approximately 30 minutes, peak effect between 2-12 hours, and duration up to 24 hours 5
• NPH insulin must be thoroughly mixed before administration by gently rotating the vial or pen (do not shake) 5
• Compared to long-acting insulin analogs (e.g., glargine), NPH has:
  • Higher risk of nocturnal hypoglycemia 6
  • Less consistent 24-hour coverage 6
  • More pronounced peak effect 6

Common Pitfalls and Caveats

1. Inadequate mixing: NPH is a suspension that settles; failure to mix thoroughly can lead to dosing errors 5
2. Fixed timing: NPH should be administered at consistent times each day to maintain stable glucose levels 5
3. Nocturnal hypoglycemia: Due to its peak action, bedtime NPH carries higher risk of overnight hypoglycemia compared to long-acting analogs 6
4. Storage issues: NPH should be stored in a refrigerator (36-46°F) but not frozen; in-use vials can be kept at room temperature (<86°F) for limited time 5
5. Dose adjustments: Many patients fail to achieve glycemic targets because of insufficient dose titration; regular monitoring and adjustment are essential 2