['It is evident that diabetes and periodontal disease are closely interrelated. Accumulation of advanced glycation end products (AGEs), coupled with exaggerated host responses to bacterial infection, may account for the increased periodontal destruction observed in patients with uncontrolled diabetes. The present study investigated the effects of AGEs on the viability of human gingival fibroblasts (HGFs) and the expression of types I and III collagen in HGFs.', 'The cell viability of HGFs was examined by methylthiazolet-etrazolium assay, whereas the expression of types I and III collagen message and protein was detected by real-time quantitative reverse transcription-polymerase chain reaction and sandwich enzyme-linked immunosorbent assay, respectively.', 'AGEs significantly suppressed the cell viability of HGFs from 24 to 72 hours (P <0.01). A high concentration of glucose (25 mmol/l) in the culture media exaggerated the inhibition of the survival rate of HGFs (P <0.01). The expression of collagen types I and III messages and proteins was significantly downregulated at 72 hours by AGEs in a concentration-dependent manner (P <0.05). Moreover, the synthesis of intracellular types I and III collagen protein was markedly inhibited by AGEs (P <0.05).'] Do advanced glycation end products inhibit the expression of collagens type I and III by human gingival fibroblasts?