Why inject at 45 degrees?

I have more trouble not agravating the skin if i don't go straight in and out.

I've never injected at 45 degrees, I shoot perpendicular with the surface, or 90 degrees.

same here, so does my mate who is a diabetic. He always goes in at 90 degrees with his insulin shots too

Going 45 degrees makes it much easier to deposit sub q. Going straight in tends to go IM. Try pinching the skin together between your thumb and forefinger and you should not have any problems.