News & Research

By: Almas Eftekhari

During pregnancy, the mother's metabolism fluctuates to accommodate the nutritional needs of her growing baby. The mother naturally becomes insulin-resistant, ensuring a steady flow of energy and nourishment for her baby as the unused sugar in her bloodstream diverts to the womb. Her body is able to counterbalance the elevated blood-sugar levels because pregnancy hormones trigger a surplus of insulin-producing beta cells.

Generating these cells in early pregnancy protects against gestational diabetes during later stages, when the baby’s energy requirements are highest and the need for insulin is critical. Until a recent study conducted at the University of California, San Francisco, scientists were unaware of the source of this protective stabilization.

American Diabetes Association-funded researcher Michael German, MD and his postdoctoral fellow, Hail Kim, MD, PhD, have discovered that serotonin is the key regulator of diabetes onset during pregnancy, and that its preventative role is influenced by the consumption of dietary protein early in the pregnancy. Serotonin is a mood-regulating hormone and neurotransmitter, often targeted in medications that treat conditions such as depression and appetite disorders. It is synthesized by the enzymes in tryptophan, an amino acid found in protein-rich foods like eggs, milk, lean meats, and fish. Expectant mothers consuming such a diet throughout the first trimester of their pregnancy tend to satisfy the serotonin and subsequent insulin levels required later when the baby’s needs surge.
 
This research suggests that dietary solutions can provide the greatest preventative impact. Dr. German’s laboratory confirmed that restricting dietary protein in pregnant mice indeed inhibits serotonin production, leading to gestational diabetes. The investigators indicate that any factor disrupting the vital hormone, such as diet, genetics, or medications, significantly increases the likelihood for developing the condition. In addition to improving the methods of treatment and prevention during pregnancy, Dr. German believes that their research could potentially lead to the reversal of other types of diabetes. The link to serotonin may also help explain depression associated with diabetes.

The results of the study are published online in the June 2010 issue of Nature Medicine and will be released in print in the near future. 

Gestational diabetes affects about 4% of pregnancies a year in the United States, posing short and long-term health concerns for both the mother and baby if left untreated. It can cause delivery complications due to excessive growth of the baby, and the condition may ultimately lead to the development of type 2 diabetes for the mother and child later in life.

(Hail K, Toyofuku Y, Lynn FC, Chak E, Uchida T, Mizukami H…German M., Serotonin regulates pancreatic beta-cell mass during pregnancy. Nature Medicine, 2010; 16(7): 804-808.)