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Meet Yale Internal Medicine: Janice Jin Hwang, MD MHS, Assistant Professor of Medicine (Endocrinology).

September 10, 2019
by Julie Parry

As part of our “Meet Yale Internal Medicine” series, today’s feature is on Janice Jin Hwang, MD, MHS, assistant professor of medicine (endocrinology).

Janice Jin Hwang, MD, MHS, assistant professor of medicine (endocrinology) jokes about how her life has come full circle. Since middle school, she loved science and doing research projects. One of those middle school projects was on sugar, showing her audience how much sugar is in various foods and how those foods tasted by comparison.

Hwang’s work at Yale School of Medicine (YSM) is at the ‘intersection of endocrinology and neuroscience.’ She studies the effect of sugar on the brain.

While completing medical school, residency and fellowship in Boston, she noticed that nearly every patient that was admitted into the hospital had some sort of metabolic dysfunction that was a contributing factor in their illness.

“Combining my love of research and human physiology, endocrinology is the perfect marriage of my interests,” said Hwang. “Endocrinology touches every organ system in the body on the most fundamental level.”

When her husband, David Hwang, MD, FAAN, FCCM, FNCS, was recruited to join the faculty at YSM, it was also an opportunity for Hwang to join the lab of former Endocrinology & Metabolism section chief Robert Sherwin, MD and focus her research on the intersection between metabolism and the brain. She quickly made a name of her herself.

“Coming to Yale was one of the best things that ever happened to my career,” explained Hwang. “Yale has a long history of excellence in research at the intersection of neuroscience and metabolism so being here is just wonderful.”

Hwang moved up within the ranks, and recently started her own lab. Their main focus is to look into all the different factors that affect how glucose and other sugars travel to and affect the brain.

In JCI Insight, Hwang and team researched fructose, a form of sugar linked to obesity and diabetes and found that it is converted in the human brain from glucose. In the study, researchers gave eight healthy, lean study participants infusions of glucose over a four-hour period. They measured sugar concentrations in their brains using magnetic resonance spectroscopy, a noninvasive neuroimaging technique. Cerebral fructose levels rose significantly in response to a glucose infusion due to a metabolic pathway called the polyol pathway that converts glucose to fructose. This study was the first time that this fructose production had been seen in humans.

This work led the team to evaluate glucose levels in the brains of individuals with obesity and type 2 diabetes compared to lean individuals. Published again in JCI Insight, Hwang and team found that, despite similar blood glucose levels across participants, individuals with obesity and diabetes had significantly lower brain glucose levels. These findings could have wide-ranging implications for understanding how the brain detects sugar.

In other research, Hwang and team looked into how the brain of someone with type 1 diabetes reacts to low blood sugar compared to healthy adults. Their conclusions, published in JCI, were that while several regions of the brain linked to reward, motivation, and decision making showed changes in the healthy participants, patients with diabetes showed minimal or no brain changes, even with mild low blood sugar.

Recently, she shared these research highlights as part of a Department of Internal Medicine Medical Grand Rounds, her first time as a presenter.

“There is so much evidence that obesity and diabetes have so many adverse associations with cognitive function, memory, depression, and even Alzheimer's disease,” explained Hwang. “The mechanisms behind why these associations happen are unknown. I think it’s really important to study the mechanisms because once you understand that, then you can develop targeted treatments.”

Hwang and team are currently recruiting both healthy lean and obese individuals as well as patients with type 1 and type 2 diabetes for several clinical trials supported by the National Institutes of Health and the American Diabetes Association. Review the list at Current Clinical Trials.

Hwang sees herself as fortunate to be within her section and at YSM.

“I have really great colleagues,” said Hwang. “The other junior faculty like myself help each other and collaborate on our work. People understand the passion for career and family. The Endocrine section has been great in that regard.”

The Section of Endocrinology & Metabolism is one of the eleven academic sections within YSM’s Department of Internal Medicine. To learn more about their work, visit Endocrinology & Metabolism.

Submitted by Julie Parry on September 10, 2019