I was diagnosed with prediabetes at age 30 and had gestational diabetes twice. My A1c and fasting glucose stayed stable with diet and exercise until last year when I turned 45, when my fasting sugar crept up a bit and I developed fatty liver. I started metformin 500 mg daily, and I'm amazed at how it has helped me lose weight. There was a noticeable decrease in my appetite. Along with upping my exercise intensity and tracking calories, I lost 10 lb with minimal hunger, and much less of the exhaustion that I had felt while dieting pre-metformin. My BMI went from 24 to 22.
My advice is to consider metformin if you are in a group for whom the American Diabetes Association (ADA) recommends it.
https://care.diabetesjournals.org/content/42/Supplement_1/S29
ADA Recommendations
3.5 Metformin therapy for prevention of type 2 diabetes should be considered in those with prediabetes, especially for those with BMI ≥35 kg/m2, those aged <60 years, and women with prior gestational diabetes mellitus. A
3.6 Long-term use of metformin may be associated with biochemical vitamin B12 deficiency, and periodic measurement of vitamin B12 levels should be considered in metformin-treated patients, especially in those with anemia or peripheral neuropathy. B