Null relationship of BMI to diabetes prevalence at baseline in the Mexico City prospective study of 150,000 adults with stored blood and 10-year mortality follow-up
METHODS: In 1998-2004, 150,000 middle-aged Mexicans joined a prospective study, with an interviewer-administered questionnaire and, from all participants, stored blood samples (plasma and DNA) and physical measurements (blood pressure, weight, height, waist and hip). Baseline data are now described; 10-year cause-specific mortality (from national mortality records) soon will be.
RESULTS: By ages 55-64, 20% of men and 23% of women had diagnosed diabetes, 29% of men and 48% of women were obese (BMI ≥30 kg/m2), and 41% of both men and women had hypertension (SBP ≥140 mmHg and/or DBP ≥90 mmHg). Waist/hip ratio was strongly correlated with diabetes prevalence but BMI was not, because the BMI-correlated measures of waist and hip circumference were oppositely related to diabetes prevalence. Given hip circumference, waist circumference was strongly positively related to diabetes. Conversely, given waist circumference, hip circumference was strongly inversely related to diabetes. Hence, waist-hip ratio was an especially strong correlate of diabetes. For hypertension, BMI and waist circumference were strongly positively related to blood pressure whereas, given waist circumference, hip circumference was weakly positively related to it. Waist-hip ratio was therefore only moderately positively related to blood pressure.
CONCLUSIONS: In this adipose, diabetic population, waist/hip ratio is a strong correlate of diabetes prevalence but BMI is not. But, BMI is a much stronger predictor of blood pressure than waist-hip ratio. The first 10-year mortality results from this prospective study will be ready for presentation to the IEA along with these baseline survey findings.