CST3 and diabetes mellitus: In univariate regression, QTVI was associated with type 1 diabetes duration and cystatin C. Backwards multivariable regression in children with diabetes, including BRS slope, QTVI and HRV as dependent variables and type 1 diabetes duration, sex, BMIz, SBPz and DBPz, HbA1c, CV and cystatin C as independent variables, resulted in a significant model for QTVI including age, type 1 diabetes duration, HbA1c and cystatin C (R=0.693, p=0.0002), with each independent variable separately significant (ESM Table 3).