Diabetes Risk Higher Among Indians in India Than in US

Pam Harrison

April 20, 2015

The prevalence of prediabetes and diabetes differs among Asian Indians depending on where they live, with those residing in the United States having a 20% higher prevalence of prediabetes than those living in India. However, the latter have a 50% higher prevalence of type 2 diabetes than those living in the United States, new research shows.

The study was published online April 15, 2015 in Diabetes Care.

"We wanted to compare the prevalence of diabetes and prediabetes in an ethnic population that is genetically similar but living in two different environments so we could get some insight into the different behavioral and environmental factors associated with increased diabetes risk in Asian Indians," Unjali Gujral, PhD, MPH, from the Laney Graduate School, Emory University, Atlanta, Georgia told Medscape Medical News.

"And the main finding of a higher prevalence of prediabetes in the US vs a higher prevalence of [type 2] diabetes in India was a novel finding and yet another piece of evidence suggesting Asian Indians may have a higher innate susceptibility to diabetes that we as physicians need to be aware of when we are screening them for disease," Dr Gujral added

"The results of our study are among the first to highlight a higher prevalence of diabetes in individuals living in India than their counterparts who have immigrated to the US," the researchers observe.

Indeed "while the prevalence of type 2 diabetes was lower in Asian Indians living in the US than in India, it was still considerably higher than in the general US population despite Asian Indians having an overall lower [body mass index] BMI," they add.

Recognizing this, the American Diabetes Association has recently recommended that Asian Americans are screened for type 2 diabetes starting at a BMI of 23 kg/m2 instead of the 25 kg/m2 that is normally recommended as a screening starting point.

CARRS vs MASALA

The investigators used two different study populations to perform their cross-sectional analyses.

The first sample included 2305 Asian Indians between 40 and 84 years of age living in Chennai, India enrolled in the Centre for Cardiometabolic Risk Reduction in South-Asia Study (CARRS). The second involved 757 similarly-aged Asian Indians living in San Francisco and Chicago enrolled in the US Mediators of Atherosclerosis in South Asians Living in America (MASALA) study.

Diabetes was defined as self-reported use of glucose-lowering medication; a fasting glucose ≥126 mg/dL, or a 2-hour glucose ≥200 mg/dL.

Prediabetes was defined as a fasting glucose between 100 and 125 mg/dL or a 2-hour glucose of 140 to 199 mg/dL, or both.

The age-adjusted prevalence of type 2 diabetes was higher among Indians in the CARRS study than those in MASALA, both overall as well as in men and in women.

Conversely, the age-adjusted prevalence of prediabetes was lower in Asian Indians in the CARRS cohort than in the MASALA cohort both overall and among both men and women.

Group CARRS (India), % MASALA (US), %
Diabetes
Overall cohort 38 24
Men 36 27
Women 42 23
Prediabetes
Overall cohort 24 33
Men 21 35
Women 25 29

Lower BMI and WC but Still Higher Type 2 Diabetes in India

While those living in India had lower BMIs and waist-circumference (WC) measurements than those residing in the United States, they still had a higher prevalence of type 2 diabetes even at normal levels of BMI and in both sexes, the authors observe.

But they had a lower prevalence of prediabetes, which may be due to a more rapid conversion through the natural history of disease in Asian Indians living in India, they note.

"We can't say exactly why this is happening, but one possible situation could be that the diabetes epidemic in India is fairly new, so that those who are at highest risk for diabetes are developing the disease the fastest," Dr Gujral speculated.

Asian Indians living in the United States might also have a lower prevalence of diabetes than those in India because of greater access to healthcare, more education, or a higher income, she added.

There may also be a shift in the association between migration and type 2 diabetes risk in this population, she and her colleagues observe.

"Our results add strength to the notion that factors besides age and central adiposity play a large role in type 2 diabetes development in Asian Indians in both developed and developing country settings, since adjustment for age, sex, waist circumference, and systolic blood pressure did not explain differences in the odds of prediabetes or type 2 diabetes between the two groups," they add.

The findings "suggest the need for collaborative longitudinal research efforts between India and the US. Such collaborations could help identify the gene-environment-lifestyle exposures that underlie the elevated risk for type 2 diabetes development in Asian Indians," they conclude.

The CARRs study is funded by the National Heart, Lung, and Blood Institute and the National Institutes of Health; the MASALA study was supported by the National Institutes of Heart as well. The authors report no relevant financial relationships.

Diabetes Care. Published online April 15, 2015. Abstract

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