CGAS and type 2 diabetes mellitus: This review comprehensively elucidates the pivotal role of the cGAS–STING signaling pathway as a molecular hub of immunometabolic regulation, integrating microenvironmental disturbances in diabetes—such as gut microbiota dysbiosis, mitochondrial dysfunction, and epigenetic alterations—to drive the pathogenesis of T2DM-associated cardiovascular complications.