Oxidative stress could precede endothelial dysfunction and insulin resistance in Indian Mauritians with impaired glucose metabolism.

Aims/hypothesis: To measure oxidative stress, endothelial dysfunction and insulin resistance in Indian Mauritians at different stages of development of Type II (non-insulin-dependent) diabetes mellitus.

Methods: Plasma total 8-epi-PGF2alpha, an indicator of oxidative stress, was determined in age-matched subjects with normal glucose metabolism (n = 39), impaired glucose tolerance (n = 14), newly diagnosed diabetes (n = 8) and established diabetes (n = 14). Plasma glucose and insulin were measured at baseline and 2 h following an oral glucose tolerance test. Endothelial function was assessed by non-invasive digital pulse wave photoplethysmography.

Results: Plasma 8-epi-PGF2alpha increased in subjects with impaired glucose tolerance (p < 0.05) compared with control subjects, and was even higher in newly diagnosed diabetic patients (p < 0.01) and established (p < 0.01) diabetic patients. A tendency towards reduced endothelial function in subjects with impaired glucose tolerance became significant in patients with newly diagnosed and established diabetes (p < 0.01), and was correlated with 8-epi-PGF2alpha (r = 0.36, p < 0.01). Insulin resistance (homeostasis model assessment) did not change in subjects with impaired glucose tolerance compared with control subjects, but increased in newly diagnosed (p < 0.01) and established (p < 0.001) diabetic subjects. The 8-epi-PGF2alpha was correlated with fasting glucose (r = 0.50, p < 0.001), triglycerides (r = 0.40, p < 0.001) and insulin resistance (r = 0.35, p < 0.001).

Conclusion/interpretation: Oxidant stress is an early event in the evolution of Type II diabetes and could precede the development of endothelial dysfunction and insulin resistance.