Twin Epidemics of Heart Disease and Diabetes among South Asians
- South Asian population has the highest risk of developing diabetes and premature heart disease.1-4 South Asians account for 20% of the world’s population but would contribute to 40% of the cardiovascular diseases (CVD) burden by 2020.3 Coronary artery disease (CAD) rates are 50% to 400% higher among Indian Diasporas compared to Chinese, Whites and Blacks and other populations with greater risk at younger ages.5
- The prevalence of diabetes is conservatively estimated to be 12-18% % in urban India and will continue to rise with increasing obesity and urbanization.6 Diabetes prevalence rates among Indian Diasporas are 2 to 6-fold higher than those of age and sex-matched Europid adults.7, 8 Over 20% of middle aged and elderly South Asian people throughout the world have diabetes.9 South Asian adults with diabetes show a markedly increased predisposition to CVD compared with Europids, especially in younger people.9 The complications of both diabetes and CVD are greater among South Asians than whites and is associated with very high and premature mortality.3 10
- INTERHEART and other studies have shown that both conditions develop at a younger age (about 5-10 years earlier) and at lower body mass index (BMI) and waist circumference (WC) among South Asians than Europids.3, 10 Importantly, diabetes is diagnosed 10 years earlier in South Asians, at a mean age of 46 years, compared with 57 years in Europids, and at a lower BMI.11 The mean age of occurrence of first heart attack is 53 years in South Asians, compared with 59 years in other populations.10
- Insulin resistance and related arthrosclerosis risk factors are highly prevalent, and develop at much lower levels of BMI and WC.3 Conventional risk factors such as dyslipidemia and smoking are equally prevalent but perhaps more potent. Novel risk factors such lipoprotein(a) are more common among South Asians and are highly correlated with premature heart attack and stroke in this population.3, 12, 13
- As a result of advanced treatment, diabetics rarely die from high blood sugar. Instead, CVD accounts for 65%-80% of all deaths among diabetics. Men with diabetes have a 2-3 fold higher risk of dying from heart attack, whereas women have a 4-6 fold high risk. Compared to white diabetics, South Asian diabetics have a 2-3 fold higher risk of dying from a heart attack. 14
- Emerging evidence suggests that both of these deadly diseases are the results of complex interplay of genetic susceptibility and environmental factors. Both diabetes and heart disease share the same precursors and are believed to spring from a common soil.15 These precursors or principal drivers include insulin resistance, abdominal obesity, atherogenic diet (high in calories and saturated fat and/or trans fat, low in fruits and vegetables), physical inactivity, and tobacco use.15-17
- Lifestyle changes associated with affluence, urbanization, and mechanization are seen in South Asians transitioning from rural to urban communities in India, as well as in South Asian Diasporas in developed countries such as Canada, US and UK.8 18-20 A higher prevalence of some high-risk alleles have been reported in South Asians.21
- Ironically, factors related to South Asian culture including diet, lifestyle and health beliefs have a significant impact on this risk of developing diabetes and CVD.22 Clinicians looking after South Asian people should be made aware of the existence of new ethnic specific criteria for screening BMI, WC, and metabolic syndrome and the need for aggressive management of conventional risk factors.3
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