INS and Insulin resistance: The gut microbiota increases insulin sensitivity through the TGR5 pathway and reduces the expression of proinflammatory cytokines (e.g., tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-1 (IL-1)) through nuclear factor kappa-B (NF-κB), which are associated with insulin resistance and oxidative damage to pancreatic β cells [66,67,68,69,70].