I'm a type 1 but I take Metformin. They started me on it because on diagnosis I was not showing classic type 1 symptoms besides being young. After a few weeks they agreed I was type 1 and I asked to go on insulin to get my levels down faster, since I was sick of feeling like **** and living off of lettuce.
Doctors told me to stay on Met because it increases insulin resistance and suppresses your liver from releasing too much sugar.
Not sure if it works though tbh, I've had plenty of hypos that have sort of cured themselves where my liver has released glucose before I even got the chance to go and grab some sweets. I tend to get hypo symptoms in the low 4's so I generally finish what I am doing before treating it, unless I am out or I can feel that it's a bad one. I know when I need to eat something, as I feel fuzzy and super shaky to the point where testing my blood sugar is actually fiddly/difficult.