Being obese might increase the chance of developing Type 2 diabetes, but the true risk factors may lie in how much overweight someone is and how long they've been that way.
Much like figuring how numbers of cigarettes smoked and years of smoking relate to lung cancer risk, researchers set out to see how degree and length of obesity factored into the risk of getting Type 2 diabetes.
They looked at data on 8,157 teens and young adults who were 14 to 21 years old at the start of a national study. Participants self-reported their height and weight and diabetes condition from 1981 to 2006.
Excess BMI (body mass index)-years - which researchers likened to smoking-pack years - were calculated by determining to what degree people were over a certain body mass index, and for how long. A BMI of 25, considered overweight, was used as a reference.