Serum creatinine level begins to increase after a decrease in glomerular filtration rate (GFR) by 50% and more, so the question emerged about a more accurate method of determining GFR. The study aimed to determine the role of renal damage markers in the diagnosis of early-stage renal disease in patients with latent autoimmune diabetes in adults (LADA). We included 84 patients with diabetes mellitus (DM) and chronic kidney disease (CKD) caused by diabetic kidney disease (DKD), as well as 25 representatives of the control group. Patients were divided into three groups – 43 people with LADA, 21 with type 1 diabetes mellitus (T1DM), and 20 patients with type 2 diabetes mellitus (T2DM). GFR was assessed using six formulas after establishing the category of GFR and albuminuria. The GFR rate estimated by the CKD-EPI formula in patients with LADA and DKD did not significantly differ from that of CKD-EPI cysC, slightly different from MDRD GFR (10.6% higher, respectively) but 21.9% lower compared to CG formula. In patients with LADA and T1DM, GFR was higher in cases with existing albuminuria, regardless of the formulas used. Thus, the non albuminuria phenotype is accompanied by a greater degree of renal impairment, which indicates the need to determine serum cystatin C in the early stages of LADA. Cystatin C levels are the most accurate, early, and independent predictor of the development and progression of CKD in patients with DM, including LADA.