CCL2 and type 2 diabetes mellitus: PM2.5 exposure has been found to aggravate type 2 diabetes, by enhancing insulin resistance through the activation of the classical cascade of inflammatory cytokines, including IL-6 TNF-α, and MCP-1, in lung as a key event at organ level, and IL-6-dependent activation of STAT3/SOC3 pathway in liver as a key event at organism level, leading to a systemic effect (Long et al., 2020).