Body weight reduction to avoid the excess risk of type 2 diabetes

It is recognised that people who are overweight have an increased risk of diabetes but the quantitative relationship is less well recognised and the extent of weight reduction needed to avoid the excess risk of diabetes through being overweight, is not well appreciated.

To derive a simple clinical algorithm to calculate the weight change needed to achieve a specified goal for reduction of body mass index (BMI, weight/height squared [kg/m(2)]) that would avoid the excess risk of diabetes and quantify the preventive effect.

Analysis of the results from two large published cohort studies of the incidence of diabetes in relation to BMI.

Epidemiological data show that the risk of diabetes doubles for every 2.5 unit increase in BMI above a BMI of 22 kg/m(2) and halves for every 2.5 unit decrease in BMI down to 22 kg/m(2). The risk of diabetes also approximately doubles for every 10 years of age. From these relationships, a simple algorithm was derived to specify a person's weight-reduction goal to avoid the excess risk of diabetes.

Converting a BMI-reduction goal (for example, 27 kg/m(2) to 22 kg/m(2)) into a percentage reduction (in this example, 19%) specifies the same percentage weight reduction (19%) because, as a percentage, the reduction is independent of height. This percentage can then easily be converted into an absolute risk reduction (in this example, a 75% reduction in risk).

The algorithm achieves two objectives: (i) it specifies the weight-reduction goal to reverse a person's excess risk of diabetes due to being overweight, and (ii) it quantifies the risk reduction.