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


OBJECTIVE
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.


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


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Environmental Preventive Medicine, Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK. n.j.wald@qmul.ac.uk
Nicholas J
NJ
Wald
Jonathan P
JP
Bestwick
Joan K
JK
Morris
D000328:Adult; D000465:Algorithms; D015992:Body Mass Index; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000517:prevention & control*; D005260:Female; D006040:Goals; D006801:Humans; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000150:complications / Q000517:prevention & control*; D012307:Risk Factors; D040242:Risk Reduction Behavior; D015431:Weight Loss / Q000502:physiology*