Obesity and type 2 diabetes mellitus (T2DM) are most serious and accelerating public health problem worldwide. Both diseases are associated with increased cardiovascular disease (CVD) and renal disease. When obesity and T2DM coexist, the risk of CVD and renal disease would increase. Therefore, preventing T2DM and weight reduction in obesity are critical issue for preventing CVD and renal disease. Recent study suggested that metabolic benefits of bariatric surgery and diet were similar apparently related to weight loss itself. However, several randomized clinical trials have shown the bariatric surgery is more effective than medical therapy for treatment of T2DM. In addition, long-term durability of weight reduction of bariatric surgery has been well documented. Moreover, large observational studies showed lower incidence of renal adverse outcomes such as diabetic nephropathy and mortality related in renal function after bariatric surgery in obese patients with T2DM compared to medical treatments. Interestingly, these benefits appeared to be consistent in patients with all degrees of kidney function. The beneficial mechanisms of bariatric surgery are under investigation. Improved metabolic parameters as well as altered molecular pathways have been suggested for potential mechanism. In this session, we will review the clinical outcomes of renal and CVD and related molecular mechanism of bariatric surgery.