Comparing Type 2 Diabetes, Prediabetes, and Their Associated Risk Factors in Asian Indians in India and in the U.S.: The CARRS and MASALA Studies

OBJECTIVE: To assess the prevalence of diabetes and prediabetes and the associated risk factors in two Asian Indian populations living in different environments. RESEARCH DESIGN AND METHODS: We performed cross-sectional analyses, using representative samples of 2,305 Asian Indians aged 40–84 years living in Chennai, India, from the Centre for cArdiometabolic Risk Reduction in South-Asia study (CARRS) (2010–2011), and 757 Asian Indians aged 40–84 years living in the greater San Francisco and Chicago areas from the U.S. Mediators of Atherosclerosis in South Asians Living in America (MASALA) study (2010–2013). Diabetes was defined as self-reported use of glucose-lowering medication, fasting glucose ≥126 mg/dL, or 2-h glucose ≥200 mg/dL. Prediabetes was defined as fasting glucose 100–125 mg/dL and/or 2-h glucose 140–199 mg/dL. RESULTS: Age-adjusted diabetes prevalence was higher in India (38% [95% CI 36–40]) than in the U.S. (24% [95% CI 21–27]). Age-adjusted prediabetes prevalence was lower in India (24% [95% CI 22–26]) than in the U.S. (33% [95% CI 30–36]). After adjustment for age, sex, waist circumference, and systolic blood pressure, living in the U.S. was associated with an increased odds for prediabetes (odds ratio 1.2 [95% CI 0.9–1.5]) and a decreased odds for diabetes (odds ratio 0.5 [95% CI 0.4–0.6]). CONCLUSIONS: These findings indicate possible changes in the relationship between migration and diabetes risk and highlight the growing burden of disease in urban India. Additionally, these results call for longitudinal studies to better identify the gene-environment-lifestyle exposures that underlie the elevated risk for type 2 diabetes development in Asian Indians.