Kryvoviaz Y. The role of cystatin C in the early diagnosis of nephropathy in patients with type 1 diabetes mellitus

The study is devoted to solving the urgent problem of modern diabetology - improving the early diagnosis and prognosis of diabetic nephropathy in patients with type 1 diabetes mellitus (DM 1). The study included 140 patients with diabetes mellitus type 1, mean age was 29,15 8,69 years, disease duration - 12,62 7,47 years, and 21 practically healthy people. Patients with diabetes mellitus type 1 are distributed depending on the level of albumin in the urine (normoalbuminuria, microalbuminuria and proteinuria) and with additional division by the level of blood cystatin C < 0,9 mg/l and > 0,9 mg/l. For the first time, a higher percentage of severe complications in the form of angiopathies in patients with diabetes mellitus type 1 with proteinuria in the groups of cystatin C and > 0,9 mg/l (50.0 % vs. 71.4 %, respectively). It was found that the level of cystatin C in the blood of patients with diabetes mellitus type 1 is 1,6 times higher than in the control group. In the control group, the level of cystatin C in the blood was 0,62 ± 0,02 mg/l, and in patients with diabetes – 1,02 ± 0,04 mg/l (p < 0,05). The concentration of cystatin C in the blood has no relation to sex, age and duration of the disease. For healthy individuals, GFR on cystatin C is 137,07 ± 27,9 ml/min/1.73 m², in patients with normoalbuminuria – 66,85 ±15,37 ml/min/1.73 m² at the level of cystatin C > 0,9 mg/l (p < 0.001). The GFR for creatinine using Cockroft-Gault formulas and CKD-EPI in the corresponding group was 121,6 ± 27,1 ml/min/1.73 m² and 118,8 ± 12,8 ml/min/1.73 m² (p < 0,05). Thus, the determination of GFR by cystatin C is an earlier marker of renal damage in the absence of albuminuria. Correlations between creatinine levels and GFR by Cockroft-Gault and GFR by CKD-EPI were characterized by gender differences. In the same patients, the correlation of blood cystatin C levels with GFR for cystatin C, neither sex factor nor the degree of albuminuria did not affect the change in their strength. This indicates that the formula for determining GFR by cystatin C in the blood gives more reliable results and works in the so-called "blind spot" of creatinine, regardless of gender.