While metformin isn’t a primary drug for T1s (or 1.5’s), I wouldn’t count it out. It has a variety of uses including inhibiting the Liver’s production of glucose (glucoseneogenesis), which can aid more than just T1s. It also has uses for polycystic ovarian syndrome (related to insulin resistance) by increasing insulin resistance. It also reduces the uptake of glucose in the GI tract.
That being said…it shouldn’t be simply given to everyone and may have little/no impact. It should be avoided or used very carefully for those at risk for lactic acidosis. And as noted above, in my case it caused digestive issues that made me strive to get off of it entirely.
Once insulin production has ceased, I would say it’s usefulness becomes more questionable, but for the LADA crowd, that could take a while.
As with everything: question everything and research/test to discover what is appropriate and helpful and what isn’t. Every person is a diffeent beast, and diabetes seems to be a case study in differentiation.