Short answer: Both are basal insulins for adults and children with diabetes.12 Humulin N is intermediate-acting human NPH insulin, a cloudy suspension with no fixed number of daily doses that can be mixed with Humulin R or Humalog. Lantus is insulin glargine, a clear solution injected once a day and never mixed. Lantus label trials compared it with NPH insulin, without naming a brand.
| Humulin N | Lantus | |
|---|---|---|
| Insulin | Human insulin isophane (NPH), intermediate-acting1 | Insulin glargine, long-acting2 |
| Look | Evenly cloudy after mixing1 | Clear and colorless2 |
| How long it works (label studies) | Median peak effect 6.5 hours (2.8 to 13) in healthy people1 | No pronounced peak; median 24 hours to end of effect vs 14.5 hours for NPH2 |
| How often | Not fixed; set for each person1 | Once daily, the same time every day2 |
| Mixing in a syringe | With Humulin R or Humalog, drawn in first1 | Not diluted or mixed with any other insulin2 |
| Forms | 10 mL vial; 3 mL KwikPen1 | 10 mL vial; 3 mL SoloStar pen2 |
| Opened pen | 14 days at room temperature1 | 28 days at room temperature2 |
| Opened vial | 31 days1 | 28 days2 |
| Missed dose | No instruction in the label1 | No instruction in the label2 |
The Lantus label reports trials against NPH insulin in which HbA1c changes were generally similar. Severe low blood sugar affected 10.6% on Lantus vs 15.0% on NPH in type 1 Study A, 8.7% vs 10.4% in Study B and 6.5% vs 5.2% in Study C; 23.0% vs 28.6% in children; and 7.8% vs 11.9% over 5 years in type 2 diabetes.2 The label says NPH insulin, not Humulin N by name.
The Lantus label starts at the same dose when switching from once-daily NPH, and at 80% of the total daily NPH dose when switching from twice-daily NPH, to lower the risk of low blood sugar. The Humulin N label says the dose may need adjusting when changing from another insulin.21 The Humulin N label has no trial table with percentages; it lists low blood sugar, allergic and injection site reactions, swelling, skin changes and weight gain.1
Which, if either, fits is for your prescriber. More detail: Humulin N side effects, Lantus side effects, the Humulin N and Lantus dosing schedules, the Lantus missed-dose page, how to store Humulin N, how to store Lantus and Lantus vs Tresiba: how do the two long-acting insulins compare?.