Metformin Metformin is a biguanide with antihyperglycaemic effects, lowering both basal and postprandial plasma glucose.
The improved glycaemic control is associated with a reduction in both fasting and postprandial plasma insulin concentrations.
In documented hypoglycemia, blood glucose tests are used along with measurements of insulin and C-peptide (a fragment of proinsulin) to differentiate between fasting and postprandial (after a meal) causes.