TPO and diabetes mellitus: The diabetes-related autoantibodies (anti-GAD, anti-islet, anti-TPO, and anti-tissue) were measured using semi-quantitative ELISA kits, which report results as optical density-based relative units rather than absolute concentrations; therefore, CV values are reported only for HbA1c Positivity for each biomarker is reported individually in Table 1 according to the manufacturer-specified thresholds.