Bone May Have a Role in Blood Sugar Control

The human skeleton plays an important role in regulating blood sugar, says a new study.

Researchers report their findings in the science journal Cell, and say their work has helped define how bone controls this process.

Led by Gerard Karsenty, MD, Ph.D., at Columbia University Medical Center, the team found that the destruction of old bone during normal skeletal regrowth - a process known as resorption - is needed to maintain a healthy level of glucose in the blood.

While resorption is a process that occurs throughout life to make way for new bone, Dr. Karsenty's team found that it also acts to stimulate the release of insulin into the bloodstream and improve the uptake of glucose by cells in the entire body.

The findings suggest that, for some people, diabetes may develop from changes in the skeleton, and that drugs designed to stimulate the bone-insulin pathway may lead to better drugs for type 2 diabetes.

Insulin Is a "Street-Smart Molecule"

In 2007, Dr. Karsenty discovered that a hormone released by bone - known as osteocalcin - can regulate glucose levels. This was a first clue that the skeleton may have an important role in regulating blood glucose.

Osteocalcin turns on the production of insulin in the pancreas and improves the ability of other cells to take in glucose. Both of these processes are impaired in type 2 diabetes.

The researchers found that osteocalcin cannot work until cells that degrade bone start working and begin the resorption process. As the cells degrade bone, inactive osteocalcin is converted to its active form by the increase in acidity around the bone.

Dr. Karsenty says insulin was discovered to favor bone resorption and it favors the activation of osteocalcin, which in turn favors insulin synthesis and secretion.

He calls insulin is a "street-smart molecule" that takes advantage of the functional interplay between bone resorption and osteocalcin.

Human Skeleton Sheds Important Light on Diabetes

By identifying the tight connection existing between energy metabolism and skeleton physiology, the study further underscores the function exerted by the skeleton.

The finding further strengthens the idea that diabetes could be treated by increasing the level of osteocalcin in the body.

In addition, the researchers suggest that since most drugs to treat another condition - osteoporosis - work by inhibiting bone resorption, the drugs may decrease the activation of osteocalcin and cause glucose intolerance in some patients.

"This research has important implications for both diabetes and osteoporosis patients," says Dr. Karsenty. "First, this research shows that osteocalcin is involved in diabetes onset, and secondly, bone may become a new target in the treatment of type 2 diabetes as it appears to contribute strongly to glucose intolerance.

"And for people with osteoporosis, the concern is that a common treatment - bisphosphonates - which work by inhibiting bone resorption and therefore may increase glucose intolerance, could push someone with borderline glucose intolerance into full-fledged disease onset. Although, more research is needed to study this further," said Dr. Karsenty.

Always consult your physician or other healthcare provider for more information.