It’s easy to blame the childhood obesity epidemic for growing cases of type 2 diabetes, but a new study finds nearly one-quarter of all diagnoses are not related to obesity.

“The finding was somewhat surprising,” said Dr. Constantine Samaan, an associate professor in the department of pediatrics at McMaster University in Ontario, Canada. “The findings highlighted to us that there is significant heterogeneity [diversity] in type 2 diabetes risk in children. We clearly do not understand all the factors that drive its occurrence.”

The researchers set out to study the issue because it wasn’t clear if obesity was universal in these patients, Samaan said. Screening has been driven by body-mass measures, so the investigators also wanted to know whether there was a subgroup of kids whose type 2 diabetes did not involve obesity.

“We had considered several possible explanations and tested for them in the study. We had thought maybe children had lost weight due to the late diagnosis of diabetes or that they may have other forms of diabetes such as genetic forms,” Samaan said. “These two possibilities did not pan out in the analysis, so we do not yet know why some children develop type 2 diabetes when they are not overweight.”

Researchers have hypothesized that there are likely children who do not produce enough insulin or are resistant to insulin, even at a normal body size.

For the new study, Samaan and his colleagues reviewed 53 studies that included nearly 9,000 participants, finding 75% of children with type 2 diabetes had obesity. Boys were more likely to be obese than girls. Asian participants had the lowest prevalence of obesity compared to other racial groups.

“Our group and others have done work in children with type 2 diabetes that have shown that these children do have excess body fat, which is, of course, seen in obesity. However, the biological functions of fat tissue, and not just amount, can profoundly impact metabolic health and may differ between those children with a normal measured body mass and those with a high body mass,” Samaan said.

“So, we are aiming to study the impacts of fat tissue amount and distribution on type 2 diabetes risk and outcomes,” he explained.

Children with diabetes also can develop other health issues, including nonalcoholic fatty liver disease, an imbalance of lipids, polycystic ovary syndrome and deteriorating kidney function.

“If families are worried, they should speak with their provider to assess the need for further testing to determine if their child is at risk of developing diabetes,” Samaan said.

While type 1 diabetes was more common, numbers of children living with either type 1 or type 2 skyrocketed in the past couple of decades in the United States.

Numbers of kids and adolescents under age 20 with type 2 diabetes grew by 95% between 2001 and 2017, according to the U.S. Centers for Disease Control and Prevention. In 2017, among kids aged 10 to 19 in the United States, 67 per 100,000 were living with type 2 diabetes.

The new report was published online Dec. 15 in JAMA Network Open.

“I think that the study does confirm that obesity is a major risk factor for the diagnosis of type 2 diabetes in children, but that as physicians we need to keep in mind that there are other risk factors besides obesity,” said Dr. Bahareh Schweiger. She is director of the division of pediatric endocrinology at Cedars-Sinai Medical Center, in Los Angeles.

Other contributing factors could be rate of weight gain, including during the pandemic, said Schweiger, who was not involved in this study. Waist circumference and an increasingly sedentary lifestyle may also contribute.

In terms of epigenetics, or the effects of the environment and behavior on how genes work, Schweiger said she would want to know the child’s stress levels, sleep habits and whether the patient is exposed to secondhand cigarette smoke.

“These are some of the other epigenetic factors that also go into play for increasing the risk for the development of type 2 diabetes,” she said.

Schweiger would also ask parents about family history of pre-diabetes, increase in urination or thirst, and unexpected weight loss.

Families can help prevent type 2 diabetes in children with healthy lifestyle modifications, she suggested.

Make sure kids are getting an hour of moderate to vigorous physical activity each day, Schweiger advised. Limit screen time. Get good sleep. Decrease household stress levels. Work on mindfulness together.

Eating meals together as a family is also an effective tool for modeling healthy eating behaviors, Schweiger suggested.

More information

The U.S. Centers for Disease Control and Prevention has more on preventing type 2 diabetes in children.

SOURCES: Constantine Samaan, MD, MSc, associate professor, department of pediatrics, McMaster University, and staff physician, division of pediatric endocrinology, McMaster Children’s Hospital, Hamilton, Ontario, Canada; Bahareh Schweiger, DO, MPH, assistant professor, pediatrics, and director, division of pediatric endocrinology, Cedars-Sinai Medical Center, Los Angeles; JAMA Network Open, Dec. 15, 2022, online