When I was first diagnosed the insulin that I was offered was NPH and Regular (Humulin R). The NPH I used in the morning and at night. the Regular was used before breakfast and before dinner. I dont remember how many units I was using however I know that it increased as I got older and started going through puberty.
The NPH is a long acting insulin that begins working about 2 hours after it is taken and lasts between 18 and 24 hours. It peaks between 4-12 hours after it has been injected.
The Regular was a short acting insulin that started working within 20-60 minutes, and lasted for about 5-8 hours. It peaks between 2-4 hours after the injection.
The chart below demonstrates the different peak times and how long each will last in comparison with eachother so you can see a little better how it is important to take the Humulin R - Regular Insulin to break down the sugar after eating:
I have tried Humalog however not for long enough to offer much feedback on it. I think it was sort of between a Regular Insulin and something like NovoRapid, which I am currently on.
Novorapid mimics the bodies reaction to sugar and works really quickly. Unlike Humulin Regular insulin, you take it as you eat Carbohydrates or Sugar. I have been following the SouthBeach Diet limiting my carbohydrates and have found that this insulin works very well for me. If I eat a salad with a chicken breast, refraining from sugar or carbohydrates - I dont need to do a shot. If I eat carbs or sugar - I do a shot. I do a certain number of units based on the number of carbohydrates I injest, minus the fiber in the food.
Lantus is now my long acting insulin which has replaced NPH. Lantus offers me a lot of freedom, and only requires one shot every 24 hours. This is great for me as it allows me to be more flexible with breakfast, lunch and dinner, as well as sleeping in and staying out late.
For more information on these insulin types as well as others - here is an interesting article.