SAN DIEGO — In a large Danish, longitudinal population-based study, boys who were overweight as children but who had returned to normal weight by age 18 did not have an increased risk of type 2 diabetes compared with those age 18 who had never been overweight in childhood.
"These findings suggest that adverse metabolic health consequences of childhood overweight are reversible and underscore the potential beneficial effects of treatment interventions in overweight pediatric populations," according to Lise Geisler Bjerregaard, PhD, from Bispebjerg and Frederiksberg Hospital, in Copenhagen, Denmark, who presented the research here at the American Diabetes Association (ADA) 2017 Scientific Sessions.
"It is very encouraging that if you are successful in losing weight, you can actually lower your risk" for type 2 diabetes, Dr Bjerregaard told Medscape Medical News.
Session cochair Ram Weiss, MD, from the Hebrew University of Jerusalem, Israel, agrees. "It's actually a very optimistic study...even though it's very difficult to [lose weight]," he told Medscape Medical News.
Since previous data have indicated that obese children can quadruple their risk of developing type 2 diabetes in the future, this work is vitally important as it indicates that if interventions are enacted when children are overweight, before they become obese, their risk of diabetes can be normalized.
There is still a need to continue to try to prevent overweight and obesity, Dr Weiss stressed, "but if [clinicians are treating] obese children, we should put all of the efforts into attempting to [help them] lose weight as they grow up."
The findings would likely apply to women and girls, Dr Bjerregaard said.
Since they previously found that boys who were overweight at 13 but not at 18 had an increased risk of type 2 diabetes, this suggests that the risk becomes greater in older children, so it is important to start tackling excess weight when children are younger, she emphasized.
Overweight Teens Tripled Type 2 Diabetes Risk, but Boys Were Okay if They Lost Weight
In a previous study, the researchers showed that risk of developing type 2 diabetes increased as BMI in boys increased. But it was not clear if weight loss could reverse this.
To investigate this, Dr Bjerregaard and colleagues analyzed data in the Copenhagen School Health Records Register from 62,565 men who were born in Denmark during 1939–1959 and had weight and height measured when they were 7 years old.
The men also had a mandatory health examination at roughly age 18 (age 17 to 26), as part of their national service, with information held on the Danish Conscription Database.
This health examination is therefore mandatory for men but not women, Dr Bjerregaard explained.
The researchers defined overweight as BMI > 17.38 kg/m2 at age 7, based upon the US Center for Disease Control and Prevention (CDC) guidelines for childhood obesity and a BMI > 25 kg/m2 at age 18, based on World Health Organization criteria.
The prevalence of overweight in this population was 5.4% at age 7 and 8.2% at age 18.
"So you see that this is a relatively slim population," Dr Bjerregaard explained.
Then, using the Danish National Patient Register, the researchers found that during a mean follow-up of 31.5 years, 6710 men (10.7%) developed type 2 diabetes at age 30 or older.
They focused on diabetes diagnosed at age 30 or older to rule out type 1 diabetes.
Of the men who were overweight in childhood, only 40% were overweight in adulthood and the rest were normal weight.
Men who were overweight boys but had a normal weight by young adulthood had a similar risk of type 2 diabetes as men who were never overweight (HR, 1.01).
Men who were persistently overweight or became overweight as young adults had three times the risk of developing type 2 diabetes as men who had always been a normal weight or were overweight only when they were 7 years old (HR, 2.88; and HR, 2.95; respectively).
Focus on Overweight in Younger Children to Normalize Adult Risk
"We conclude that boys with overweight who normalize their weight from age 7 to 18 years do not carry an increased risk of type 2 diabetes in adulthood," Dr Bjerregaard said.
"Our results suggest that the adverse effects of child overweight on the risk of type 2 diabetes may be reversible, and they highlight the need for normalizing weight among children with overweight."
"These results are encouraging," she stressed, adding that "we need to find out whether the results apply to other noncommunicable diseases [associated with obesity] such as cancer and cardiovascular disease and whether they apply to women in addition to men," she concluded.
The study is part of the DynaHEALTH project and was funded by the European Commission's Horizon 2020 program. Dr Bjerregaard and her coauthors have no relevant financial relationships.
American Diabetes Association 2017 Scientific Sessions. June 9, 2016; San Diego, California. Abstract 11-OR
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