Injecting the Lantus slowly can help for some people, but what I find the best is taking an ice cube and pressing over the skin where I will inject my Lantus for about 4-5 seconds (or however cold you want to get it, the colder, the less sting) and then inject the
Lantus. The body
is more concerned with the cold effects of the ice cube
than the acidity of the Lantus and while it may not remove the sting entirely, I have found it reduces it drastically.