Researchers at the School of Medicine have discovered a protein in the pancreas that may explain the mechanisms of gestational diabetes, a condition that affects four percent of all pregnancies.

Gestational diabetes occurs in women whose bodies cannot produce enough insulin to keep up with the body’s increased need for the hormone, according to Emeritus Professor of Cardiovascular Medicine Gerald M. Reaven. Although gestational diabetes is sometimes referred to as a temporary case of diabetes — sugar levels return to normal after the baby is delivered — the condition has lifelong implications for both the mother and child.

“This study marks the first genetic model of gestational diabetes,” said Developmental Biology post-doctoral researcher Satyajit Karnik, the first author on the study. “Previously, people had to inject mice or manipulate them another way.”

The team discovered that expressing the protein menin prevented mice from producing enough insulin, a hormone the body uses to break down sugar. This decrease in insulin causes hyperglycemia — the build-up of sugar in the blood — a defining characteristic of gestational diabetes.

Researchers used a number of tools that allowed them to use mice to explore the complex relationships of the pregnancy hormones. The Nobel Prize in Physiology or Medicine was awarded this year to the creators of one tool that the team used — gene targeting.

“Because they become more insulin resistant during pregnancy,” Reaven said, “[mothers] who develop gestational diabetes are more at risk for developing diabetes later on in life. Treating these conditions substantially increases the chances of having a good, healthy pregnancy.”

Karnik envisioned future uses of the research, such as developing genetic screening for gestational diabetes and menin-based strategies to treat diet or obesity induced forms of diabetes.

He cautioned, however, that the genetic model is from mice.

“It is not a definitive connection between gestational diabetes in humans,” Karnik said. “But it gives us a good idea of where to look.”

Other Stanford researchers involved in the study include postdoctoral scholars Hainan Chen and Michael Yen; research associate Graeme W. McLean; M.D./Ph.D. student Jeremy Heit; research assistant Xueying Gu; Andrew Zhang, and Assistant Prof. of Pathology Magali Fontaine.