CST3 and Hyperglycemia: The rationale for our study was twofold: 1) simultaneous hyperglycemia is known to affect GFR under experimental conditions [14], [22]–[24]; and 2) while simultaneous hyperglycemia may increase GFR under controlled settings, the association of blood glucose variability with cystatin C based eGFR measurements is uncertain in patients with T1D in clinical studies or clinical care settings.