Several studies around the world have consistently revealed excess, early, and extensive CHD in persons of South Asian origin. The excess mortality has not been fully explained by the major conventional risk factors in cross-sectional comparisons with other population groups. Diabetes mellitus and impaired glucose tolerance are, however, highly prevalent in South Asian migrants. Central obesity, high levels of triglycerides, and low levels of HDL cholesterol, with or without glucose intolerance, seem to characterize a phenotype frequently noted among South Asian migrants.

Thus, South Asians in urban and migrant environments may be at a higher risk of CHD due to the confluence of (1) genetic factors that predispose to higher lipoprotein(a) levels, the central obesity/glucose intolerance/dyslipidemia complex collectively labeled as the "metabolic syndrome," and a possible "thrifty gene" effect with (2) environmental influences that lead to weight gain, rise in plasma cholesterol and blood pressure levels, and, as yet inadequately studied, probable psychosocial risk factors.