Male 58, my A1c is 5.8 and fasting glucose varies 140 to 150, this is with metformin 500 mg from last seven days. initially the medicine caused stomach pain and nausea, but now they have gone. random glucose also varies from 140 to 190. It appears that my pancreas have lost its regulatory function. Dr has advised adding another 500mg of metformin. please advise and comment.