Is neutral protamine Hagedorn (NPH) insulin the same as Humulin N (brand‑name NPH insulin)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: September 18, 2026 • View editorial policy

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question

Yes, NPH insulin and Humulin N are the same medication.

Humulin N is simply the brand name for NPH (Neutral Protamine Hagedorn) insulin manufactured by Eli Lilly. 1

Key Points

According to the FDA drug label, Humulin N is explicitly described as "insulin isophane human suspension (NPH)" 1. The formulation contains human insulin combined with protamine sulfate to create the characteristic intermediate-acting NPH insulin crystals. The amino acid sequence is identical to human insulin, produced through recombinant DNA technology 1.

Understanding the Terminology

  • NPH = the generic type of intermediate-acting insulin (named after its inventors: Neutral Protamine Hagedorn)
  • Humulin N = Eli Lilly's brand name for their NPH insulin product
  • Both terms refer to the same insulin formulation with identical pharmacologic properties

Clinical Implications

The American Diabetes Association guidelines confirm that intermediate-acting insulins include NPH 2. When the evidence refers to "NPH insulin," this encompasses all brand formulations including Humulin N, as well as other manufacturers' NPH products like Novolin N.

Important caveat: While Humulin N is NPH insulin, the reverse is not always true—NPH insulin can be manufactured by different companies (Humulin N by Lilly, Novolin N by Novo Nordisk). Research comparing different NPH formulations shows they have similar glycemic control efficacy 3. However, you should not interchange brands without medical supervision and patient notification 2, as guidelines emphasize that changing insulin formulations should always be done under medical oversight.

Pharmacologic Profile

Humulin N/NPH has:

  • Intermediate-acting duration
  • Median peak effect at 6.5 hours (range: 2.8-13 hours) 1
  • Contains protamine sulfate (0.35 mg/mL) as the retarding agent 1
  • Appears as a white, cloudy suspension 1

References

2
Guideline

insulin administration.

Diabetes Care, 2004

Related Questions

What should the 8 am and 8 pm neutral protamine Hagedorn (NPH) insulin doses be, and how should the insulin‑to‑carbohydrate ratio and insulin‑sensitivity factor be adjusted for a 47‑year‑old male with type 2 diabetes, weight 120 kg, normal renal function, relapsed diffuse large B‑cell lymphoma post‑CAR‑T therapy receiving multiple dexamethasone (Decadron) doses, currently on NPH 30 U at 8 am and 25 U at 8 pm with a ratio of 1 U per 6 g carbohydrate and an insulin‑sensitivity factor of 1 U per 20 mg/dL and recent blood glucose values of 245‑317 mg/dL?
In a 66-year-old male (88.6 kg, creatinine 1.29 mg/dL, eGFR 61 mL/min/1.73 m²) on continuous tube feeding (232 g carbohydrate per 24 h) who received 30 units of NPH insulin at 2100 h with an insulin‑sensitivity factor of 25 mg/dL per unit and blood glucose readings of 146 mg/dL at 2100 h, 97 mg/dL at midnight, and 70 mg/dL at 0320 h, what should his morning NPH insulin dose be at 8 am and what should his insulin‑sensitivity factor be?
For a 67‑year‑old female weighing 76 kg with type 2 diabetes on continuous tube feeding (132 g carbohydrate per 24 h) who received 35 U NPH insulin at 9 pm and has been on an insulin infusion since then, what NPH dose should be administered this morning?
What 8 am dose of NPH (neutral protamine Hagedorn) insulin should be given to a 67‑year‑old male with type 2 diabetes, weight 142 kg, serum creatinine 2.10 mg/dL (GFR 29 mL/min), one week post‑liver transplant, on continuous total feed (201 g carbohydrate per 24 h) with an insulin‑to‑carbohydrate ratio of 1 unit per 10 g carbohydrate but minimal oral intake, who received 20 units of NPH at 8 pm and has been on an insulin drip with rates of 2,2,2,3,3,4,4,3,3,3 units/h since 8 pm and wishes to discontinue the drip?
For a 47-year-old male weighing 120 kg who is on dexamethasone 10 mg every 6 hours, what should the 10 am NPH (neutral protamine Hagedorn) insulin dose be, what should the 8 pm NPH dose be, and what should the insulin sensitivity factor (ISF) and insulin-to-carbohydrate ratio (ICR) be after changing dexamethasone to 10 mg every 8 hours?
When should a multiplex vaginitis PCR panel be ordered instead of a point‑of‑care wet preparation?
What medications should be started in patients with anxiety who have a history of deep vein thrombosis?
In diabetes insipidus, does a low urine osmolality cause an elevated serum osmolality?
What is tinea versicolor (pityriasis versicolor) and how does it present?
In a patient with recurrent multidrug‑resistant urinary tract infections, recently hospitalized and currently receiving meropenem, piperacillin‑tazobactam, amoxicillin‑clavulanate (Augmentin), methenamine hippurate, and phenazopyridine, with normal white blood cell count and normal creatinine, should we obtain a vaginal swab for Gram stain and culture before starting intravaginal miconazole 2% cream?
What is the appropriate management of a painful chin furuncle in a 49-year-old homeless Caucasian woman present for three days?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.