When 1500 mg metformin or placebo was given with a mixed liquid meal in participants with well-controlled type 2 diabetes (mean HbA1c 48 mmol/mol [6.5%]), the overall postprandial GLP-1 response was greater with metformin than placebo, but this increase was evident approximately 2 h after the meal [14]. This evidence concerns the gene GCG and type 2 diabetes mellitus.