Humalog and Novolog are different types of fast acting insulin, meaning that they are quickly absorbed into your system to immediately drop your blood sugar. Some people find that one works more effectively than the other, so which
is used
is really up to the patient. Humulin, more commonly called Humulin NPH, and even more commonly called just NPH, is a long acting insulin. It is absorbed more slowly, and it's effects last longer, about 12 hours.