The kidney is the main metabolising organ of vitamin D. When the kidney is damaged by DN, not only vitamin D metabolism and activation will be disturbed to a certain extent, but also the glomerular filtration rate will be increased and tubular reabsorption is impaired, resulting in the loss of the protein-bound 25-OH-D3 due to proteinuria, and the level of 25-OH-D3 is negatively correlated with the UACR and positively correlated with the blood albumin, which is in agreement with our results. Here, ALB is linked to liver dysplastic nodule.