Did you ask the consultant why he or she had prescribed this? Other than because your sugars are still high?
Metformin can be given to type 1s but is normally given to type 2s because it works by getting the body to stop producing glucagon (insulin's antagonist) in such big quantities. It might help reduce sugars a little and is very safe though can have digestive side effects. It can help with weight loss too for similar reasons.