SLC16A13 encodes monocarboxylate transporter 13 (MCT13), a proton-linked plasma membrane transporter with broader substrate specificity than initially characterized. Beyond its canonical role transporting monocarboxylates like lactate 1, MCT13 functions as a basolateral oligopeptide transporter in intestinal epithelial cells, mediating electrogenic transport of peptides and peptidomimetics 2. Transport function is modulated by extracellular potassium ions and ancillary proteins such as basigin/CD147 3. In metabolic disease, genome-wide association studies identified SLC16A13 as a type 2 diabetes susceptibility locus 1. The rs312457 risk allele (G) associates with increased diabetes risk in Chinese populations, correlating with reduced pancreatic beta-cell function 4. Mechanistically, SLC16A13 deletion in mice reduces hepatic lactate availability, increasing AMPK activation and mitochondrial respiration while decreasing lipid accumulation and hepatic insulin resistance 1. In cancer pathology, SLC16A13 upregulation correlates with malignant progression in oral squamous cell carcinoma and pancreatic cancer 56. Conversely, SLC16A13 downregulation induces apoptosis and reduces cell viability in gastric and lung cancer cell lines 78, suggesting context-dependent roles in tumorigenesis. These findings position SLC16A13 as a potential therapeutic target for metabolic and neoplastic diseases.