INS and type 2 diabetes mellitus: As race/ethnicity, presence of T2D, use of exogenous insulin, and the interassay variation of insulin measurements all influence the HOMA-IR, and due to the fact that serum insulin concentration is not routinely measured in the clinic, population-based or at least local thresholds will need to be established before broadly recommending the use of the HOMA-IR across all clinical settings.