Provided herein are methods of increasing lipoprotein lipase (LPL) activity, by inhibiting apolipoprotein C3 (ApoCIII), which removes the ApoCIII inhibition of LPL, and permits VLDL to be converted to LDL. Also provided are methods for treating or preventing a lipid metabolism disorder, such as type 2 diabetes by use of an ApoCIII antagonist. Also provided are screening methods to identify ApoCIII antagonists.