I Am A Brittle Diabetic Currently Taking Metformin 1000 Mg

I am a brittle diabetic currently taking Metformin 1000 mg twice a day. I also take Humalog three times a day on a sliding scale and 45 units of Tujeo at night at bedtime.
I recently saw an article about not taking Metformin if using Humalog. Is it something I need to discuss with my doctor or just let it go and figure he knows what's right.
My sugar is usually between 400 and 600. I was on he above with Lantus, but since changing to Tujeo I've now gone down to 182 to 258.