Metformin Lactic Acidosis

In an outpatient setting, when should we be concerned about this?

I have an attending that won’t let me start patients on Metformin if they have very high A1cs because he says it can increase risk of lactic acidosis.

I can’t find this in any literature anywhere. I see a discussion about renal impairment, hepatic impairment and chronic conditions predisposing to increased oxygen consumption (CHF).

Any good sources on this (or good sources I can give my attending to read so he stops bringing this up everytime I mention starting a newly diagnosed diabetic on metformin).