Metformin is a big-time insulin sensitizer, which means that the more you take it, the better your results will likely be. For most people, I recommend taking Metformin at bedtime for best results. However, if you have trouble sleeping with metformin in your system or prefer to take it earlier in the day (say 6:00 AM), then do what works best for you! In general though, my recommendation is to start with 1/2 tablet of 500 mg and work up from there as necessary. If this amount causes any GI upset or other adverse effects such as constipation or gas then reduce dose accordingly. Always check with a doctor before starting an anti-diabetic medication!