On my Metformin bottle, it says something about a brecalet but that’s for people with type 1 or advanced type 2, correct?
Diabetes is complicated: insulin levels in the blood vary based on what foods you eat, medications you take, exercise levels, the time of day, how much insulin your own body still can produce (and whether it just can't supply enough or it can supply enough but "overshoots the runway" and produces too much), whether you are well or sick, etc. Not enough insulin leaves glucose in the bloodstream that damages organs. Too much insulin can cause hypoglycemic episodes, and, if those are severe enough, you can pass out -- or worse. This can happen quite suddenly -- and, worse, some people don't experience or are not aware of the symptoms, so they can't feel them and bring up their blood glucose by themselves before it's too late.
The bracelet (necklace, whatever) is there in case
you don't recognize or cannot respond to the symptoms quickly enough to increase your blood glucose levels yourself and someone finds you out cold on the floor. It's also useful, in the event of a car accident or the like, for medical professionals to know you have diabetes and are taking medication for it. People with Type 1 and advanced Type 2 diabetes are more susceptible to hypoglycemic episodes, yes, but any person with diabetes could have them.
Since you're taking only Metformin, the risk of going hypo is quote low. However, as with any medications you take, interactions between drugs can result in unexpected effects. Your doctor should be monitoring these potential interactions and letting you know they exist, but it's always good to know yourself that medications can interact, sometimes in a bad way.
I hope that helps you decide whether you should get a medical-alert bracelet/necklace/whatever.