Is Insulatard (NPH insulin) used as a bolus insulin?

Insulatard (NPH Insulin) is Not Used as a Bolus Insulin

No, Insulatard (NPH insulin) is not used as a bolus insulin but rather as an intermediate-acting basal insulin that covers the body's basal metabolic insulin requirements. 1

Classification and Pharmacokinetic Profile of Insulatard (NPH)

• NPH insulin is classified as an intermediate-acting insulin that regulates hepatic glucose production as part of basal insulin coverage 1
• It has a distinct pharmacokinetic profile with:
  • Onset of action: 1-2 hours
  • Peak effect: 4-6 hours
  • Duration of action: 12-18 hours 1
• This intermediate-acting profile contrasts with the rapid onset and short duration needed for bolus insulin 1

Appropriate Bolus Insulin Options

• Bolus (prandial) insulins are specifically designed to reduce glycemic excursions after meals and require:
  • Rapid onset of action
  • Short duration of effect
  • Timing aligned with meals 1
• Appropriate bolus insulin options include:
  • Human regular insulin (short-acting)
  • Rapid-acting analogs (aspart, glulisine, lispro)
  • Ultra-rapid acting formulations (faster insulin aspart)
  • Inhaled insulin 1

Proper Role of NPH Insulin in Diabetes Management

• NPH insulin is appropriately used as:
  • A basal insulin administered once or twice daily 1
  • Part of a premixed insulin formulation (e.g., 70/30 NPH/regular) 1
  • A specific option for steroid-induced hyperglycemia due to its peak effect aligning with peak steroid effect 2, 3
• When used in basal-bolus regimens, NPH serves as the basal component while a separate rapid-acting insulin provides the bolus component 1

Clinical Implications and Potential Pitfalls

• Using NPH as a bolus insulin would lead to:
  • Delayed onset of action (1-2 hours) resulting in initial postprandial hyperglycemia 1
  • Prolonged insulin effect (12-18 hours) increasing risk of late hypoglycemia 1
  • Misalignment between insulin action and meal absorption 4
• The pharmacokinetic profile of NPH makes it unsuitable for meal coverage compared to rapid-acting insulins that have:
  • Faster onset (10-15 minutes)
  • Earlier peak (1-2 hours)
  • Shorter duration (3-5 hours) 4, 5

Special Considerations

• In resource-limited settings, human regular insulin (not NPH) may be used as a bolus insulin despite not being ideal 1
• NPH can be used in specific clinical scenarios such as steroid-induced hyperglycemia where its peak aligns with the peak hyperglycemic effect of morning prednisone 2, 3
• When mixing insulins, NPH can be combined with rapid-acting or short-acting insulins for immediate use, but specific guidelines should be followed 1

NPH insulin's intermediate-acting profile makes it fundamentally unsuitable as a bolus insulin where rapid onset and short duration are required for effective postprandial glucose control.