I have always, as far as I can remember, had high sugar level results when having my blood tested for annual check-ups. However nothing was ever done about recommendations or advice from the various doctors over the years. Recently after a yearly physical a doctor started me on metformin which made me physically very drained, not tired or weak, but very loose, if that is the right word, and sort of wiped out in a physical sense. The prescription dose was 500 mg.