Insulin was administered in a Macrosol (medium chain monoglyceride) formulation.Increases in total insulin in blood plasma were observed over the 1st 20 min in 5 out of 6 subjects receiving the insulin in Macrosol, at later times, in response to this, the suppression of endogenous secretion of insulin was indicated by the marked reduction in C-peptide in the blood.A small reduction in glucose was also observed, presenting a consistent picture of insulin, C-peptide and glucose changes in accord with those to be expected after administration of exogenous insulin.