Leukocyte Telomere Length, DNA Oxidation, and Risk of Lower-Extremity Amputation in Patients With Long-standing Type 1 Diabetes

OBJECTIVE Telomere shortening and DNA oxidation are associated with premature vascular aging, which may be involved in lower-extremity amputation (LEA). We sought to investigate whether leukocyte telomere length (LTL) and plasma 8-hydroxy-2 '-deoxyguanosine (8-OHdG), a biomarker of DNA oxidation, were associated with LEA in subjects with type 1 diabetes at high vascular risk. RESEARCH DESIGN AND METHODS LTL (quantitative PCR) and plasma 8-OHdG concentrations (immunoassay method) were assessed at baseline in the GENEDIAB (Genetique de la Nephropathie Diabetique) type 1 diabetes cohort. Logistic and Cox proportional hazards regression models were fitted to estimate odds ratio (OR) (at baseline) and hazard ratio (HR) (during follow-up), with related 95% CI, by increasing biomarker tertiles (T1, T2, T3). RESULTS Among 478 participants (56% male, mean +/- SD age 45 +/- 12 years and diabetes duration 29 +/- 10 years), 84 patients had LEA at baseline. Baseline history of LEA was associated with shorter LTL (OR for T2 vs. T1 0.62 [95% CI 0.32-1.22] and for T3 vs. T1 0.41 [0.20-0.84]) but not with plasma 8-OHdG (1.16 [0.56-2.39] and 1.24 [0.61-2.55], respectively). New cases of LEA occurred in 34 (12.3%) participants during the 10-year follow-up. LTL were shorter (HR T2 vs. T1 0.25 [95% CI 0.08-0.67] and T3 vs. T1 0.29 [0.10-0.77]) and plasma 8-OHdG higher (2.20 [0.76-7.35] and 3.11 [1.07-10.32]) in participants who developed LEA during follow-up compared with others. No significant interaction was observed between biomarkers on their association with LEA. CONCLUSIONS We report the first independent association between LTL shortening and excess risk of LEA in type 1 diabetes. High plasma 8-OHdG was also associated with incident LEA but partly dependent on cofounding variables.