INS and periodontitis: During periodontitis, LPS can stimulate innate immune cells, such as dendritic cells and macrophages, to secrete a large amount of IL-12,41 resulting in a significant increase in serum IL-12 levels.72 High levels of IL-12 can downregulate the protein expression of Klotho in β-cells,73 inhibit the activity of the transcription factor PDX1,73 and promote the transdifferentiation of β-cells into α-cells,74 thus exacerbating the dysfunction of insulin secretion by β-cells.