Metabolic effects of combined sulphonylurea and metformin therapy in maturity-onset diabetice

Twelve hour metabolic studies have been performed in two groups of maturity-onset diabetics treated either by sulphonylurea and metformin therapy or sulphonylurea therapy alone. There was no significant difference in blood glucose concentration between the two groups although serum insulin concentration was significantly higher in the group treated by sulphonylurea therapy alone. Concentrations of several intermediary metabolites were higher when metformin formed part of the therapy. Thus, mean blood lactate, pyruvate, alanine and total ketone body concentrations and the lactate/pyruvate ratio and 3-hydroxybutyrate/acetoacetate ratio were all significantly elevated during sulphonylurea and metformin therapy. It is concluded that the use of metformin with a sulphonylurea results in widespread abnormalities in blood concentrations of intermediary metabolites.