a time marked by decreased insulin sensitivity, or by early adulthood, according to data from a study of Danish men.
“This large-scale longitudinal study showed that men who had remission of overweight between 7 and 13 years of age and had subsequently maintained a normal weight in early adulthood had a risk of type 2 diabetes similar to that among men with normal weights at all of these ages,” Lise G. Bjerregaard, PhD, of the Center for Clinical Research and Prevention in Copenhagen and her colleagues wrote in the New England Journal of Medicine.
Studies in adults have shown that lowering body weights and body mass indexes delayed the onset of type 2 diabetes. While correcting body mass index seems to benefit adults, little is known about how being overweight or obese as children and young adults can affect the risk for type 2 diabetes. This is a particularly pressing issue because almost a quarter of children in developed countries are either overweight or obese.
The investigators looked at the heights and weights of 62,565 Danish men during childhood, measured at 7 and 13 years of age, and during early adulthood between 17 and 26 years of age. The height and weight data were obtained from two national health databases. The Copenhagen School Health Record Register (CSHRR) contains information on most of the children in Copenhagen who attended school during 1930-1989. The researchers then corroborated the information from this database and connected it with data from the Danish Conscription Database, which included heights and weights of men born during 1939-1959 that was taken at conscription examinations. In addition, diagnoses of type 2 diabetes were obtained from the Danish National Patient Register.
A little more than 10% (6,710) of the 62,565 men in the study were diagnosed with type 2 diabetes during the course of the 2 million person-years of follow-up. The prevalence of being overweight increased from 5.4% to 8.2% from age 7 years of age to early adulthood.
The risk of developing type 2 diabetes was heavily dependent on how old patients were when they were overweight and at what age they reduced their bodyweight. Being overweight at any age corresponded to an increased risk of type 2 diabetes. Men who were overweight during early adulthood had the highest incidence of type 2 diabetes. An encouraging finding was that men who had been overweight at age 7 years but had reduced their bodyweight by age 13 years and maintained a stable bodyweight as young men had a risk of being diagnosed similar to men who had never been overweight (hazard ratio, 0.96; 95% confidence interval, 0.75-1.21). Similarly, men who had been overweight only at age 13 years or between ages 7 and 13 years had a lower risks of developing type 2 diabetes than did men who had been persistently overweight, but the risks were still higher than in men who had never been overweight (overweight only at 7 and 13 years of age vs. never overweight: HR , 1.47; 95% CI, 1.10-1.9; persistently overweight vs. never overweight: HR, 4.14; 95% CI, 3.57-4.79). Men who had been overweight later in life had a higher risk of type 2 diabetes, compared with men who were only overweight as young adults, but the risk was similar to men who had been overweight at all ages.
The findings from this study are supported by the large sample size and the length of follow-up. Unfortunately, the researchers analyzed exclusively men and no information was available for early-life explanatory factors like pubertal timing and parental socioeconomic class or later-life body mass index.