do you prefer injection or capsule?

Depending on what type of diabetes you have is how you control it. There are many types, just like cancer, and different treatment methods work for different people. If you are type 1, then you must take insulin injections. There is no other option. Well, there is the insulin pump that is always connected to you, but that's still an injection every 3 days to replace the spot it goes into you. If you are type 2, there are many treatment methods such as diet, exercise, pills, and then insulin. Generally, type 2 treatment goes that route as well. You start control with diet and exercise. Then as it progresses you start on pills and eventually go to insulin. It's just the way it is.

As far as I know you start off with pills but always have to go onto injections eventually. The only way to stop having to do this is to have a really good diet, with no sugar and only complex carbohydrates and to reduce your fat intake.