Out of nine tested parameters (age, duration of diabetes, systolic and diastolic blood pressure, albumin excretion rate, serum HbA1c, CRP, TGF-β1, and creatinine), it turned out that TGF-β1 in serum had the most discriminative power in predicting the occurrence of DR in juvenile patients with T1DM. This evidence concerns the gene CRP and diabetes mellitus.