Project Summary/Abstract Type 2 diabetes affects over 30 million people in the US and carries a high burden of cardiovascular morbidity and mortality. Identifying new, modifiable mechanisms that may influence the development and macrovascular complications of this multifactorial disease will make a substantial public health impact. This application will investigate the associations of hydrogen sulfide (H2S) with risks of incident diabetes and diabetes-associated cardiovascular disease (CVD). H2S is a gasotransmitter that is crucial for cell signaling and cell function. In addition, H2S appears to play an important role in the development of diabetes and mitigating the related toxicities. In the pancreas, H2S regulates insulin secretion and protects beta cells from apoptosis. In the liver, the main organ for the synthesis and storage of glucose, H2S reduces insulin resistance and improves glucose uptake. In preclinical studies, compounds that release H2S, and therefore increase systemic concentrations, protect from endothelial dysfunction, cardiac hypertrophy, myocardial injury and atherosclerosis in rodent models of diabetes. Studies in humans are limited to cross-sectional studies showing a reduction in plasma H2S in patients with type 2 diabetes. Prospective studies are needed to bridge the gap between pre-clinical studies and future clinical trials. Therefore we propose to conduct efficient case-cohort and longitudinal studies of H2S, diabetes and CVD. We hypothesize that higher levels of H2S in plasma are associated with lower risks of incident diabetes and diabetes-associated CVD; and we hypothesize that cellular H2S levels protects human hepatic and cardiomyocyte from insulin resistance and the resulting cellular dysfunction. To test these hypotheses, we will measure circulating H2S levels in existing samples from two prospective cohorts and examine H2S associations with type 2 diabetes and diabetes-associated CVD (Aim 1). Importantly, in Aim 2, we supplement these observational studies with functional experimental studies in human derived cell lines to investigate the molecular mechanism of H2S hepatic and cardiac protection in insulin resistance, and to discover novel H2S-regulated pathways that may lead to future targets for the prevention of diabetes and CVD.