Is There Any Difference Between Glumetza Metformin And Co-metformin?

I was taking 500mg of Glumetza metformin daily for about 3 years and everything was fine. I Changed pharmacies and they are prescribing me 500 mg of co-metformin. I assume this is a generic drug. Since taking the co-metformin my blood sugar levels have increased by about 25%. I feel sluggish and generally not myself. The pill has an arrow type shape ^ on one side and M/M on the other. Is there a difference between the 2. I know some co-metformin pills are made overseas, which worries me. What do you think?