A heightened risk for type 2 diabetes in adulthood was eliminated in overweight boys who achieved a normal weight by puberty and sustained it into early adulthood.

To determine whether the risk for type 2 diabetes mellitus (DM) in adulthood can be mitigated by weight reduction in overweight and obese children, researchers examined type 2 DM incidence at ages 30 to 60 years in a longitudinal study of 62,000 Danish men from boyhood. Evaluations occurred at age 7 years, at 13 years, and as young adults (ages 17–26). Results were as follows:

* Eleven percent of men developed type 2 DM over nearly 2 million person-years of follow-up.

* The prevalence of overweight was 5% at age 7 years, increasing to 8% in young adulthood.

* While overweight at any age was associated with elevated risk for later type 2 DM, overweight as a young adult conferred the highest risk.

* Boys who were overweight at age 7 years but had normal weight by age 13 years and thereafter were at no greater risk for type 2 DM compared with men who were never overweight.

* Men who were overweight at age 13 years and as young adults had a greater risk for type 2 DM compared with men who were overweight only as young adults.

* Among some 500 boys who were obese at age 7 years, 33% remained obese in early adulthood; reducing their body-mass index (BMI) to overweight or normal levels by early adulthood was associated with significant reductions in their future risk for type 2 DM.

* Men who were obese in early adulthood had high risk for type 2 DM regardless of their BMI during childhood.