The significantly decreased genes in DPN were also uniquely enriched in endocrine and metabolic disease (Level 2 category), which included the AGE–RAGE (advanced glycation end product–advanced glycation end product receptor) signaling pathway in diabetic complications, and nonalcoholic fatty liver disease; the relaxin signaling pathway in the endocrine system (Level 2 category); diabetic cardiomyopathy of cardiovascular disease (Level 2 category); and the VEGF signaling pathway in signal transduction (Level 2 category) (Figure 3A). Here, VEGFA is linked to diabetic cardiomyopathy.