Diabetes and cardiovascular disease: related disorders created by disturbances in the endogenous clock

The factors underpinning the development of type 2 diabetes mirror closely the presentation of atherothrombotic risk factors that enhance risk of macrovascular disease. It has been postulated that this relationship is so tight as to indicate that diabetes and cardiovascular disease are the same condition with common genetic and environmental antecedents ('the common soil hypothesis'). The huge Increase in prevalence of type 2 diabetes in the Asia-Pacific region in recent years has raised serious concerns regarding the cardiovascular consequences for these populations. For example, in the UK, subjects of S. Asian origin have a higher prevalence of type 2 diabetes with a relative risk of macrovascular disease of -1.5 compared to the Indigenous population. Current opinion favours the view that the development of obesity is associated with an insulin resistant phenotype that promotes vascular risk. Our endogenous clock is regulated centrally in the hypothalamus by light exposure and in peripheral tissues to place our metabolic needs in time with day length and the seasons. Evidence from animal and cellular studies with early data from human studies indicates that disruption of the endogenous clock as can occur with obesity, is associated with a metabolic syndrome phenotype. The adaption of western lifestyles by S Asian subjects may promote disruption of circadian rhythms with associated increases in both diabetes and cardiovascular disease.