Sheela Magge

Johns Hopkins pediatric endocrinologist Sheela Magge knows that people of South Asian descent are at greater risk of developing type 2 diabetes, compared with white and Black peers of the same age, sex and body mass index (BMI). But she doesn’t know why.

“If we can identify the cause of this higher risk, maybe we can have a more personalized approach to prevention and treatment,” says Magge, director of the Division of Pediatric Endocrinology and Diabetes.

A study, published June 1 in Diabetes Care, points to some answers. Magge and colleagues, including Talia Hitt, also a Johns Hopkins pediatric endocrinologist, found that adolescents and young adults of South Asian descent have higher amounts of visceral and liver fat than their peers, and appear to hyper-secrete insulin compared with white and African American peers of similar BMI, sex and pubertal stage.

Earlier studies had highlighted a paradox known as the “thin fat Indian baby,” which found that babies born in India generally weigh less than white babies born in England, yet have a higher percentage of body fat. South Asian adults are also known to develop diabetes and other cardiovascular diseases eight to 10 years earlier than people of other ancestry groups.

In addition, Magge says, because of the worldwide obesity epidemic, more youth are developing diabetes, hypertension and other conditions that were once considered adult diseases — with dire implications for long-term complications.

For the study, Magge and her colleagues compared metabolic mechanisms in South Asian, white and African American adolescents and young adults of similar BMI percentiles, who were not known to have diabetes.

The researchers defined South Asian ancestry as having at least three grandparents who identified as being from India, Pakistan, Sri Lanka, Nepal, Bhutan, the Maldives or Bangladesh. 

Study participants were considered African American or white if they had three or more grandparents identifying as belonging to those groups. (Magge notes that this is self-identified ancestry, and plans to analyze collected samples for genetics and metabolomics as well.)

The study found important variations in ectopic (liver and visceral) fat, insulin sensitivity, and insulin secretion among the different groups, says Magge. More research is needed to fully understand how those factors interact with each other and contribute to diabetes risk, she says.

“What we want to do now is a longitudinal study to learn how and when the transition to diabetes occurs,” she says. “We are hypothesizing that perhaps these young South Asians start out hypersecreting insulin in response to insulin resistance, and maybe then burn out their pancreatic beta cells, which make insulin, sooner than people of other ancestry groups, causing diabetes.

“We also don’t know whether the larger amounts of ectopic fat cause diabetes development, or are just associated with it,” she says.

Continued research, says Magge, could eventually prompt more personalized diagnosis and treatment of type 2 diabetes.