Abstract: Oleoyl estrone or estrone monooleate is a fatty-acid monoester of an estrogen which appear to be useful for the preparation of a medicament for the treatment and/or profilaxis of a human suffering from a metabolic disease selected from the group consisting of diabetes mellitus type 2, hyperlipidemia (hypertriacylglyceridemia, hyperlipoproteinemia, hypercholesterolemia) and the Metabolic Syndrome X associated with glucose intolerance, hyperinsulinemia, or insulin resistance. Compared with insulin, oleoyl-estrone has the advantage of being aministered orally. The effectiveness of oleoyl-estrone as oral antidiabetic is conspicuous since it does not act as a simple hypoglycemic agent, but goes to the root of the problem lowering insulin resistance. The additional hypolipemic effect allows to extend its use for the treatment of dislipemias.