Metformin efficacy and tolerance in obese non-insulin dependent diabetics: a comparison of two dosage schedules

Summary

A comparative open study of metformin unit doses of 500?mg and 850?mg was carried out in 64 obese, non-insulin dependent diabetics on 1.5 to 3?g metformin daily. Glycaemic response, blood lactate, plasma metformin concentrations and tolerance for metformin were assessed. On changing from a 500?mg unit dose to an equivalent total dose of metformin using the 850?mg preparation, there were no significant changes in the random blood glucose, glycated haemoglobin, or blood lactate concentrations. Metformin plasma concentrations remained unchanged except for patients transferred from 1.5 to 2.0?g daily to 850?mg twice daily; in these patients plasma concentrations increased from 1.83±0.87 to 2.50±0.89 μg/l (p < 0.01). Seven patients (3 asymptomatic and 4 with background symptoms) became intolerant of the 850?mg regimen and required to return to the 500?mg dose regimen. After exclusion of patients intolerant of the 850?mg dose regimen (11%), the remaining patients noted no significant change in symptoms and 28% of all patients transferred to the 850?mg dose unit indicated an overall preference for this regimen.