The telomere is a repeating end-chromosomal DNA sequence that reflects chronological and also biological ageing. We and others have observed a shortened telomere length in people with type 1 and type 2 diabetes, especially those with end-organ complications. However, cellular factor(s) that shorten telomere length in diabetes are not known. Candidates secondary to increased ambient glucose include oxidant stress, advanced glycation end-products (AGEs), and the hexosamine pathway. In Recent clinical trials, fenofibrate protected against a broad range of diabetes complications, although whether it affects telomere length is unknown. The aim of this work was to develop an in vitro system to examine effects of the diabetic milieu on telomere length, and possible protection by fenofibrate. Primary cultures of human dermal fibroblasts (CRL-2097), were serially passaged and treated with elevated D-glucose (25mM) compared with 5mM, and across 7 days with AGEs-BSA or control-BSA prepared in house, glucosamine, or hydrogen peroxide (H₂0₂). A high-throughput qPCR assay, adapted from published literature, was used to measure relative telomere length (T) by comparing it to a single copy gene (S)¹ , which was then normalised against a human standard. Initial data showed serial passage of cells in normal glucose conditions caused a reduction in T/S ratio of ~3% per passage (95%CI 7-10), whereas high glucose caused ~5% reduction per passage. While AGEs-BSA (3.8μM) did not affect T/S ratio, H₂0₂ (10 μM) and glucosamine (5mM) caused 17.1% and 19.8% respective reductions in T/S ratio after 7 days’ treatment (each P<0.05 vs parallel untreated control T/S ratio: 0.97±0.13). In subsequent studies, co-treatment with fenofibrate (100μM) attenuated by 43% the significant reduction in T/S caused by H₂0₂ (10μM), This data indicates that telomere shortening by a diabetic metabolic environment and potential protective agents can be studied in vitro and will enable cellular mechanisms of effect to be defined.