When cystatin C levels were added to age, duration of diabetes, race and ethnicity, and HbA1c in the UK, the analysis showed acceptable performance, with an AUC of 0.779 compared with an AUC of 0.735 without cystatin C. In India, the model with age, duration, and HbA1c had performance closer to chance, with an AUC of 0.552, and adding cystatin C had close to acceptable performance with an AUC of 0.696. Here, CST3 is linked to diabetes mellitus.