CD4+ T cell subset imbalance drives renal inflammation and fibrosis in diabetic kidney diseaseT Cell Imbalance Linked to Kidney Damage in Diabetic Patients

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes and a leading cause of end-stage renal disease. Recently, immune and inflammatory mechanisms have been recognized as critical in the pathogenesis of DKD, among which CD4+ T cell subset imbalance serves as a key contributor to renal inflammation and fibrosis. This narrative review synthesizes evidence from PubMed, Web of Science, and EMBASE (inception to March 2026) to provide a comprehensive overview of the immunopathological roles and molecular regulatory networks of major CD4+ T cell subsets, including T helper type 1, T helper type 2, T helper type 17 and regulatory T cells, in mediating renal injury through signature cytokines and signaling pathways. We also discuss the regulatory effects of hyperglycemia, hypoxia and lipid disorders on CD4+ T cell function, as well as the crosstalk between renal resident cells and CD4+ T cells via pathways such as programmed death-1/programmed death ligand-1 and nuclear factor-kappa B in amplifying inflammatory responses. Moreover, we outline current therapeutic strategies targeting CD4+ T cells, including traditional Chinese herbs, biologic agents, nonsteroidal mineralocorticoid receptor antagonists, sodium-glucose cotransporter 2 inhibitors and stem cell therapy, and evaluate their potential and limitations in balancing T cell subsets and alleviating renal injury. Although these approaches show promise, translating them into precise immunotherapy for DKD will require deeper mechanistic insight and rigorous clinical validation.