What is considered a “high” spike?

New here, but have had my numbers pretty under control since diagnosed (3 ish weeks now) My Dr. said if I have three spikes in a week I have to get on metformin (I’ll know for sure by Monday). My spikes have never been over 125, and I had 3 last week and so far this week I’ve had 2. I guess I’m just looking for experience and opinions on this medication during the last 7ish weeks of pregnancy -