Google Berberine PubMed.
Use Berberine. Works better, cheaper, actually healthy for you instead of potentiating dementia like Metformin.
Controlled Labs Blue Sugar is $20 at Nutraplanet for a month.
Bulk powders and solo Berberine capped products can be had even cheaper.
Reduce the percentage of carbs in your diet substantially, and try to eat them only after training or immediately prior. Nothing will outrun a bad diet, and if your insulin sensitivity is poor you need to focus on fats and proteins predominantly to lose body fat (and of course be eating less than you need to maintain bodyweight).