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.

Insulin regular starts working quickly, within 30 minutes, and is given prior to meals, while insulin NPH starts to work within 2-4 hours and lasts longer than insulin regular and is used for longer periods of blood sugar control.