Birthplace Weighs Heavily on Immigrant Weight and Risk for Diabetes

Reena Oza-Frank, the study's lead researcher from Emory University, Atlanta, GA, stated, "There was a clear link between being overweight and having diabetes for certain migrant groups, but not for others."  

Generally, immigrants have better health profiles than those born in the US. However, it has been shown that immigrants who arrive in the US at younger ages are more likely to be overweight with increasing time spent in America than are immigrants who come to the US at older ages. 

While prior studies have addressed the health of people born abroad, these typically lumped all immigrants together and compared them to native-born Americans, Oza-Frank and her Emory colleague, K.M. Venkat Narayan note in a report. 

To get a more detailed picture, they looked at data on more than 34,000 US immigrant adults categorized by nine regions of birth who participated in the National Health Interview Survey. Most of them had been living in the US at least 15 years when they reported their diabetes status and body mass index (BMI) -- a standard measure of weight in relation to height used to gauge how fat or thin a person is. 

Significant differences between immigrant groups with regards to body weight and diabetes emerged. 

For example, immigrants from Central Asia fared particularly well, the investigators found, with only about 24 percent being overweight, as defined by a BMI of at least 25. (The BMI cut-off for obesity is 30.) And even for those who were overweight, the rate of diabetes remained relatively low -- around 3 percent. 

Among people from the nearby Indian subcontinent, however, the overall rate of diabetes was 10 percent -- the highest across all nine birth regions and three times greater than among European immigrants. Yet they were no more likely to be overweight. 

Immigrants from Mexico, Central America and the Caribbean were at greater risk of being both overweight (around 60 percent) and diabetic (more than 5 percent) than European immigrants. 

Obesity, diabetes and immigration are all on the rise in the US. About one out of every three Americans is now obese, and approximately one in ten have diabetes. Meanwhile, nearly a quarter of children have at least one immigrant parent. 

Jennifer Van Hook, who studies the health of immigrant children at Pennsylvania State University, University Park, states that, "Immigrants are going to have a major impact on the overall health of the US population simply on account of their size and growth." 

Several factors could explain the diverse responses to American life. Van Hook noted the range of possible circumstances for immigrants both before and after their arrival. For example, people coming from poorer countries where under-nutrition is a major concern may not consider being overweight a problem.

Because obesity and diabetes rates vary substantially both across and within US states, where an immigrant family settles can also be a factor, said Van Hook. Access to healthy foods and exercise can differ substantially even between nearby neighborhoods.

Given the nature of the study, the Emory researchers had to trust that participants accurately self-reported their weight and diabetes status. They were also limited to considering one point in time for each immigrant. "By examining changes over time, such as weight patterns, we could better assess the link between weight and diabetes," said Oza-Frank. 

Future research could help identify particularly vulnerable groups for interventions, and further disentangle genetic, cultural and environmental factors -- for both foreign- and native-born residents. 

"How immigrants respond in terms of their weight when they move to the United States," Van Hook noted, "is often taken as an indicator of how the US environment contributes to obesity." 

American Journal of Public Health, February 2010.