Overweight children are at an increased risk of developing heart diseases at an early age, a new study from Denmark says.

Researchers analyzed the health records of nearly 500 children who were being treated at various hospitals across the country and found that children who are overweight at a young age tend to become obese later and develop many health problems including heart disease and diabetes.

The study results are based on information available from the Dutch Paediatric Surveillance Unit between 2005 and 2007.

Doctors in Netherland treating overweight children aged between 2 and 18 had to supply information to the Dutch Paediatric Surveillance Unit about their patients' health like their blood glucose levels, blood pressure and blood fat report.

Researchers found that two out of three study participants had at least one risk factor for heart disease.

The researchers also found that almost half of the children had high blood pressure and bad cholesterol levels. Some had high blood glucose levels and were already diagnosed with diabetes.

"The prevalence of impaired fasting glucose in [these children] is worrying, considering the increasing prevalence worldwide of type 2 diabetes in children and adolescents. Likewise, the high prevalence of hypertension and abnormal lipids may lead to cardiovascular disease in young adulthood," the authors wrote.

According to World Health Organization, in the year 2010 almost 42 million children were diagnosed as being overweight. Of these almost 35 million live in developing countries.

"Internationally accepted criteria for defining severe obesity and guidelines for early detection and treatment of severe obesity and [underlying ill health] are urgently needed," the authors concluded, according to a statement.

Childhood obesity in the U.SThe Centers for Disease Control and Prevention (CDC), says that 17 percent of all children in U.S or 12.5 million children and teens in the country are affected by obesity.

In the past few years childhood obesity has almost has tripled, the agency says.

The study was published in the journal Archives of Disease in Childhood.