Association between lipid peroxidation and risk of type 2 diabetes in women.

In-vitro and animal studies demonstrate that lipid peroxidation plays an important role in the pathogenesis of type 2 diabetes (T2D). However, human data from prospective studies are limited and contradictory. We used data originally collected in two nested case-control studies of cancer to prospectively evaluate whether systemic levels of lipid peroxidation were associated with incidence of T2D in 1917 women who were 40-70 years old and diabetes-free at baseline. Lipid peroxidation was measured by urinary F₂-isoprostanes (F₂-IsoPs) and its major metabolite 2,3-dinor-5,6-dihydro-15-F_2t-IsoP (F₂-IsoP-M) with GC/NICI-MS assays. The Cox regression model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident T2D. After a median follow-up of 10.1 years, 187 women were diagnosed with T2D. Urinary concentrations of both F₂-IsoPs and F₂-IsoP-M were significantly higher in T2D cases than in non-cases. Both biomarkers were positively associated with subsequent risk of T2D in multivariable-adjusted Cox models. When further adjusted for body mass index (BMI), the positive association with F₂-IsoP-M was attenuated and no longer statistically significant, whereas the association with F₂-IsoPs remained (P for overall significance < 0.001). HR for T2D was 1.68 (95% CI: 1.13, 2.51) for the highest vs the lowest quartile of F₂-IsoPs. Moreover, this association appeared more pronounced among women with higher BMI. In summary, our study suggests that F₂-IsoPs could be of significance in T2D risk prediction among middle-aged and elderly women.