BMI, WHR, and your risk of diabetes

I've written previously about Body Mass Index and Waist to Hip ratio and their usefulness in assessing your overall health. There's been some controversy in medical circles, however, about whether Body Mass Index (BMI), Waist to Hip Ratio (WHR) or simple Waist Circumference (WC) is a better predictor of type 2 diabetes.

Researchers in Augsberg, Germany conducted a prospective study of 6,732 men and women between the ages of 35 and 74, who were free of diabetes at the study outset (Am J Clin Nutr 2006;84(3):483-9). Their weight, height, waist and hip circumferences were measured, their blood tested for cholesterol levels, and their blood pressure was taken. Further, participants were interviewed regarding their genetic history of diabetes, their exercise levels and whether they smoked.

Over ten years later the participants in the study were recontacted and asked if they had been diagnosed with diabetes. Of those who said they did, the researchers found that the following was true:

Generally, higher BMI at the beginning of the study was positively associated with type 2 diabetes for both men and women, even after controlling for age, genetic history of diabetes, cholesterol levels, smoking status, and physical activity. This remained the case even after controlling for Waist to Hip Ratio.

Higher Waist Circumference alone also predicted type 2 diabetes in both sexes, although for men the association was weaker than for BMI. For women, the association was about the same as for BMI.

For Waist to Hip Ratio alone, the higher ratio increased the risk of type 2 diabetes for both men and women, but not as strongly as BMI.

What's really important is what the researchers observed after analyzing two or more measurements together: they found that the risk of type 2 diabetes in men was highest for those men who had both a high BMI AND a high Waist Circumference. For women, the highest risk was for both a high BMI and a high Waist to Hip ratio or a high Waist Circumference. Interestingly, those women with a low Waist Circumference and a high BMI had no significantly increased risk of type 2 diabetes even after adjusting for multiple variables.

What this means for you:

It's clear that no one single measurement is going to definitively predict your risk of type 2 diabetes or any other health problem. This study, however, provides another set of indicators that you and your doctor can use to assess your overall health. Measure your Waist to Hip Ratio and your Body Mass Index and share the results with your doctor if you haven't already.

First posted: September 20, 2006