Metabolic syndrome is a combination of medical disorders that increase the risk of developing cardiovascular disease and diabetes.It affects one in five people, and prevalence increases with age. Some studies estimate the prevalence in the USA to be up to 25% of the population. Metabolic syndrome is also known as metabolic syndrome X, syndrome X, insulin resistance syndrome,Reaven's syndrome, and CHAOS (Australia). A similar condition in overweight horses is referred to a equine metabolic syndrome it is unknown if they have the same etiology.