Online calculator simplifies weight-related diabetes risk

By Sally Robertson, B.Sc.Jun 8 2012

A simple algorithm that is available online can be used to calculate how much weight a patient needs to lose to achieve a body mass index (BMI) that avoids excess diabetes risk, report researchers.

The "Beat Diabetes Calculator" (http://www.lmsalpha.co.uk/beatdiabetes/) enables conversion of a person's BMI reduction goal into a more readily understandable weight-reduction target, given as the percentage of bodyweight they need to lose to reverse any excess risk for diabetes due to being overweight. The tool also calculates the resulting reduction in risk for developing diabetes in the next 10 years.

"For a particular person who knows his or her BMI, it is simple to determine the BMI reduction goal, but converting this into a weight reduction goal is more difficult because each person's weight reduction depends on their height," explain Nicholas Wald (Queen Mary university of London, UK) and colleagues in the British Journal of General Practice.

To develop a method for calculating weight-reduction goals, the team analyzed epidemiologic data from two large cohort studies: one performed on males and the other on females.

The team established that the risk for diabetes doubles for every 2.5 unit increase in BMI above an "optimal" BMI of 22 kg/m² and halves for every 2.5 unit decrease in BMI down to 22 kg/m². They also determined that the risk for diabetes approximately doubles with every 10-year increase in age.

These relationships were then used to create the weight-reduction algorithm that determines the change in risk for a given change in BMI that can then be converted into the percentage weight reduction required to achieve the optimal BMI of 22 kg/m².

"Informing a person of their weight-reduction goal rather than their BMI reduction goal, together with a quantitative estimate of the benefits of achieving that goal, should focus attention on how to avoid the substantial risks of diabetes arising from being overweight," say Wald et al.

"Even if person's weight reduction goal is only partially achieved, the gains are considerable and still worthwhile," they conclude.

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