Fmoc-Ala-OH- 13 C 3 is a 13 C-labeled Fmoc-leucine. Fmoc-leucine is a selective PPARγ modulator. Fmoc-leucine activates PPARγ with a lower potency but a similar maximal efficacy than rosiglitazone. Fmoc-leucine improves insulin sensitivity in normal, diet-ind