A new method for diagnosis of diabetes mellitus is proposed, which uses for measurement a lyophilized blood plasma sample prepared in the form of a pellet. The paper develops a methodology for fast spectroscopic measurements of such pellets with terahertz pulse time-domain holography. For that reason, blood plasma pellets were experimentally measured by terahertz time-domain spectroscopy system in transmission mode and its characteristics were obtained to be then used in numerical simulation of pulse terahertz hologram formation and extraction of its optical properties. Thus, a demonstration of the proof-of-concept was given for the techniques of pellet inspection, which contains information about the presence of glycated proteins, reflecting a diabetic pathology.