Last year (Jan 2014), I was prescribed Metformin SR 500 mg once a day tab when my Hb1Ac was around 6.5. Since then I have lost 20lbs and feel a lot better and continue to take the medication once a day. My blood sugar (fasting, PP and random) are within normal ranges. I have developed severe itching and a rash on my Rt. ring finger since I have started taking this medication and want to know if I can substitute it with another oral hypo-glyceminc medication.