Thus, an attempt was made to measure NE, S100B, and NSE levels using ELISA tests in blood serum samples collected before the COVID-19 pandemic from patients with (1) T2DM and (2) advanced-stage diabetic nephropathy (NfT2DM); (3) a healthy group; and in blood serum samples collected two years after recovering from COVID-19 from patients with (4) T2DM and (5) NfT2DM. Here, ENO2 is linked to diabetic kidney disease.