Among the female T1D patients without DN carrying genotypes A/A, A/G and G/G, however, there were significant differences in cystatin levels (0.79 ± 0.17, 0.81 ± 0.14 and 0.75 ± 0.12 mg/L, P = 0.021). This evidence concerns the gene CST4 and type 1 diabetes mellitus.