the present invention relates to methods for determining whether a mammal has a disease , such as diabetes , using pet data analysis techniques . these methods include administering to a mammal a pet - compatible tracer , such as a radioligand specific for a vesicular monoamine transporter 2 receptor , and measuring total functional β - cell capacity of the mammal &# 39 ; s pancreas using pet data analysis techniques . methods for tracking the efficacy of a treatment for diabetes , for evaluating the regeneration of β - cells in a pancreas , and for monitoring a patient with a transplanted pancreas are also provided .