Dorte Vistisen and Kristine Færch, from the Steno Diabetes Center in Gentofte, Denmark, and colleagues analyzed data from participants of the Whitehall II cohort, a group of London-based civil servants who have been followed for more than a decade, to see what changes in body weight and other parameters had occurred in people in the years before they were diagnosed with diabetes.

6,705 participants were free of diabetes when they entered the study and are included in the analysis here. They were tested for diabetes every 5 years, and 645 of them were subsequently diagnosed with the disease. Going back to measurements of body mass index (or BMI, calculated using height and weight) which were recorded regularly, the researchers used a statistical method to identify patterns of change in BMI among individuals who went on to develop diabetes.