I was diagnosed with diabetes, shouldn’t my doctor suggest Metformin?

I was diagnosed with diabetes in 2015. I had been able to bring my A1C down through lifestyle and diet changes, which allowed me to avoid medication. However, I have been trending up for over a year. My last A1C taken in late April was a 7.0 and my doctor still feels I should stick it out with diet and exercise and to come back in 6 months for another A1C test. Is this normal advice? Shouldn’t he suggest Metformin to try to avoid long term damage for not being in a normal range? I appreciate any advice on this matter. Thank you.