What are the differences between humulin (insulin) r and humulin (insulin) n?

Humulin. Humulin is the marketed name by Eli Lilly and Company. Both are biosynthetic human insulin. Humulin N, is neutral protamine hagedorn (NPH), an intermediate-acting insulin, has an onset of 1-3 hours, peak of 8 hours and duration of 12 to 16 hours. Humulin R is Regular insulin, a short-acting insulin, has an onset of 30 to 60 minutes, a peak of 2-4 hours, and a duration of 5-8 hours.