New Delhi: Migrating? Be wary of diabetes and heart disease. That is the message coming from new research that concludes that migrants of almost every race in the world are more vulnerable to these diseases and show prevalence rates up to four times higher than their kin in the home country.
The study—by endocrinologists Anoop Misra and Om P. Ganda and to be published soon in online journal Nutrition, according to the authors—has found the risk of diabetes and cardio-vascular diseases escalating as migrants—both inter-country and intra-country—become increasingly affluent, adopt new dietary habits and lead stressful lives in new habitats.
Diabetes is a disorder that sees low or no production of insulin, a chemical key for absorption of sugar into body cells. The disorder has no cure and can only be managed by insulin injections or medication that will stimulate the hormone’s production in the body and sensitise body cells to make do with less amounts of the vital chemical.
While unhealthy lifestyle and genetic predisposition were thought to be the major culprits pushing people into chronic diseases, the new study could help identify ‘migration’ itself as a risk factor and map the vulnerable segments and focus prevention programmes better.
“Even between two places with equal urbanization, the migrant is at a higher risk in the new habitat. This shows how environmental factors can override underlying genetics,” says Dr Misra, the head of diabetes & metabolic disease treatment at New Delhi’s Fortis Hospital. “Even now, we are seeing large scale migration from rural to urban areas and between countries and this population is continuously at risk. Public health agencies should focus on this segment.”
The Misra-Ganda research, which trawled through published studies on migration, obesity, heart disease and diabetes since 1966, concludes that the effects of migration are worst on South Asians, a population that has a high incidence of type-II diabetes mellitus, the commonest form of the disorder that results from inadequate production of insulin.
Migrant South Asians, the study found, developed type-II diabetes four times more than their peers who stayed back in their place of birth. This pattern is robust even in case of Africans, Hispanics, Chinese, Japanese, Greeks and European populations that migrated across different routes, over decades to economies such as the US.
Similar observations have been reported for intra-country migrants—rural to urban migration as in India—and even for resettled tribes such as the Australian aborginals.
People of African origin show a ‘stepwise increase’ in obesity that matches their path of migration over the centuries, Dr Misra and Dr Ganda conclude. While African Americans had obesity prevalence of 39%, their kin in Jamaica showed obesity in 23% of population. Among those in Nigeria, the ones that never migrated, the rate was a mere 5%. A similar stepwise increase was found in people living in rural India (8.4%), urban India (13.6%) and those of Indian origin settled in the US (17.4%).
But, there are nationalities who managed to buck the trend. Dubbing it as the ‘healthy migrant effect’ or ‘salmon bias’, the Misra-Ganda study gives examples of how some sections among Mexicans that moved to the US, held on to their traditional diets, lifestyles and managed to escape these ailments.
Rajarshi Sengupta, executive director with consultant PricewaterhouseCoopers, believes that “diabetes and other chronic diseases pose a grave danger” to present day economies. A report by the firm and industry body Assocham estimated in April that chronic diseases could cost India a staggering $200 billion (Rs8.2 trillion) between 2005 and 2015 in foregone national income.