Body mass index, waist circumference, and the risk of type 2 diabetes mellitus: implications for routine clinical practice

Abstract

Background: Current guidelines for assessing the risk of developing type 2 diabetes mellitus (DM) recommend using the patient's body-mass index (BMI) as a primary measure. Waist circumference measurement is recommended for overweight or obese patients only (BMI > or = 25).

Methods: We studied the interaction between BMI and waist circumference with respect to the risk of developing type 2 DM in a cohort of 9753 men and 15491 women, aged 35 to 65, who participated in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam. The statistical analysis was performed with multivariable-adjusted Cox proportional hazard regression.

Results: During a mean follow-up interval of 8 years, type 2 DM was newly diagnosed in 583 men and 425 women. A statistically significant interaction was found between BMI and waist circumference with respect to the risk of type 2 DM (p<0.0001). The positive association between waist circumference and diabetes risk was stronger in persons with lower BMI. The relative risk (RR) of developing type 2 DM among persons of low or normal weight (BMI < 25) who had a large waist circumference was at least as high as that among overweight persons (BMI 25-29.9) with a small waist circumference: for the first case, the RR was 3.62 [1.67-7.83] in men and 2.74 [1.52-4.94] in women; for the second case, the RR was 2.26 [1.51-3.37] in men and 1.40 [0.61-3.19] in women (The figures in square brackets are 95% confidence intervals). These relative risks were calculated in comparison to the risk among persons of low or normal weight (BMI < 25) with a small waist circumference.

Conclusion: These findings imply that the waist circumference is an important additional piece of information for assessing the risk of type 2 DM, particularly among persons of low or normal weight.

Figure

Relative risk of type 2 diabetes in men and women in dependence on BMI and waist circumference. The reference group are persons of BMI<25 and waist circumference ≤ median. The sex-specific median was 94 cm for men and 78.5 cm for women. The squares and circles signify relative risks and the error bars signify 95% confidence intervals, calculated by Cox proportional hazard regression, with age as time at risk, stratified by age and adjusted for height, smoking habits, alcohol consumption, physical activity, level of education, highest school-leaving exam and physical stress at the workplace. The relative risks were plotted on a logarithmic scale (y-axis).