The key findings of the present study were that type 1 diabetes increased the vasorelaxant efficacy of endogenous H2S in rat cerebral arteries and enhanced vascular biosynthesis of H2S, as assessed by increased vasorelaxation to the H2S substrate l-cysteine and increased CSE mRNA production in the type 1 diabetic group. The gene discussed is CTH; the disease is type 1 diabetes mellitus.