Disclosed herein are methods of detecting blood disorders, such as diabetes. In particular examples the method includes contacting a blood sample with an amine reagent, blocking an excess of the amine reagent with a blocking reagent, digesting the modified blood sample with trypsin to produce a digested blood sample containing a plurality of glycated N-terminal peptides and non-glycated N-terminal peptides, then analyzing the digested blood sample with MALDI MS. Also provided are reagents for use in such methods.