Moreover, it has been shown that in individuals with pre-existing conditions such as type 2 diabetes mellitus (T2DM) or advanced diabetic nephropathy, COVID-19 can significantly elevate levels of intracellular proteins, such as neutrophil elastase (NE), neuron-specific enolase (NSE), and neuronal protein S100B. This evidence concerns the gene ENO2 and type 2 diabetes mellitus.