Epidemiology: Open Access
Open Access

Abstract

O besity is a modifiable risk factor for type II diabetes. We evaluated the association between obesity and diabetes risk among 11,455 diabetes cases and 12,837 controls (total=24,292) in the BioServe Global Epidemiology Study (GES). The GES is a multinational study to assess disease risk factors with subjects recruited from countries including the United States, Poland and India. For diabetes, newly diagnosed subjects provided informed consent and were asked about health behavior indicators using the same translated survey instrument. We used multivariate unconditional logistic regression to calculate odds ratios to assess the association between Body Mass Index (BMI) and risk of diabetes and its' interaction with physical activity. For all subjects combined, the multivariate Odds Ratio (OR) for diabetes was 2.91 (95% Confidence Interval (95% CI): 2.72-3.11) for individuals who were obese (BMI>30 Kg/m 2 ) compared to healthy-weight (BMI 18.5-24.9 Kg/m 2 ) individuals after adjusting for age, gender, race and pack-years of smoking. Obese individuals of different races in the study population, Caucasian-Americans (OR: 8.04, 95% CI: 6.99-9.25), African-Americans (OR: 5.21, 95% CI: 3.73-7.29), Hispanic-Americans (OR: 4.06, 95% CI: 3.05-5.42), Polish- Caucasians (OR: 9.35, 95% CI: 7.22-112.10), South Indian Dravidians (OR: 2.10 95% CI: 1.68-2.63) and North Indians (OR: 2.00, 95% CI: 1.02-3.90) were all at significantly increased risk of diabetes compared to healthy-weight individuals. However, the magnitude of the association between BMI and diabetes was lower among Indian individuals. The dietary consumption of whole grains, including rice, was ~13-fold higher in South and North Indian cases and controls than among the other ethnicities examined. We postulate that Indians primarily develop insulin resistant type II diabetes due to over consumption of carbohydrates. In all categories of our study, there was a statistically significant dose response increase of diabetes risk when over-weight and obese subjects were compared to healthy-weight subjects. For every unit increase in BMI we observed an approximately 13% increase in risk of diabetes (P<0.0001). Results from our study strongly confirm that maintenance of healthy weight is an important public health message in the effort to reduce increasing incidence of type II diabetes. Our study also suggests that increased physical activity reduces the obesity-diabetes risk association among Caucasians and African-Americans but not among Indians and Hispanic-Americans. Among Caucasians and African-Americans increased physical activity was associated with reduced diabetes risk within all weight categories. However, among Hispanic-Americans and Indians physical activity was not associated with reduced risk of diabetes. This finding suggests that the interventions that include exercise may yield different results depending on the race of the individual.

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