Endocrine Abstracts

Purpose: To assess the level of biomarkers of early kidney damage (urinary and plasma cystatin C) in patients with prediabetes and to characterize their association with risk factors for the development of nephropathy.

Materials and methods: The object of the study were 60 patients (32% men, 68% women) with early disorders of carbohydrate metabolism (impaired fasting glycemia (IFG) and impaired carbohydrate tolerance (IGT), WHO criteria, 2009). The mean age in the group was 44.3 ± 7.8 years. The average level of fasting glycemia diagnosis was 5.7±0.42 mmol/l, the average level of glycated hemoglobin was 5.96±0.36%. The mean BMI was 31.6±5.4 kg/m². All participants underwent a morning urine test for microalbuminuria (MAU), assessment of creatinine levels, followed by calculation of GFR (MDRD). Urinary and plasma levels of cystatin C were analyzed by enzyme immunoassay using the Cystatin C-ELISA-Best test system. Statistical processing of the results was carried out using the program Statistica 7.0. using: χ2 test, Mann-Whitney U-test for two independent samples, Spearman test. Differences were considered significant at P<0.05.

Results: The mean urinary cystatin C was 10.3±1.2 mg/l. An elevated urinary level of cystatin C was observed in 54.6% of the subjects. Тhere were significant differences in the level of the analyzed urinary marker in the group of patients with MAU (P<0.001). A direct correlation was also established between the concentration of cystatin C in urine with BMI (r= 0.42, P<0.01), SBP (r= 0.59, P<0.05), DBP (r= 0.34, P<0.05), creatinine level (r= 0.68, P<0.001), glycemia during oral glucose tolerance test 2 h after exercise (r= 0.51, P<0.01) and negative correlation relationship with GFR level (r= 0.59, P<0.01). The mean plasma level of cystatin C was 1.02 mg/l. There were significant differences in the level of the analyzed plasma marker in the group of patients with MAU (P<0.01). Direct relationship was established between the concentration of cystatin C and blood creatinine (r= 0.61, P<0.001), the severity of MAU (r= 0.61, P<0.001), the age of patients (r= 0.42, P<0.05) and an inverse relationship with the level of GFR (r= - 0.65, P<0.01).

Conclusions: An increase in the level of analyzed markers in patients with prediabetes demonstrates kidney damage at the stage of early carbohydrate metabolism disorders. The revealed changes in the levels of urinary and plasma cystatin C, compared with traditional nephrological markers (MAU, GFR), indicate a higher diagnostic significance in the light of early detection and enable preventive intervention in terms of prevention.