Bones offer new hope for diabetes


Aug 10, 2007

Bones may play a more active role than previously thought in regulating the body's chemistry, scientists say.

An international team found the molecule osteocalcin, produced by bone cells, is active in helping to regulate blood sugar levels in mice.

This is important in the development of diabetes and obesity, so the findings, in the journal Cell, offer the hope of new ways to treat these conditions.

But experts have warned more research is needed to confirm the link.

The researchers looked at two different mice strains, both of which had altered activities of osteocalcin, which is produced by osteoblast cells in bones.

One strain had no osteocalcin gene, and so no osteocalcin, and the other had increased levels of osteocalcin activity.

Novel function

Lead author Professor Gerard Karsenty of the Columbia University said: "Osteocalcin has been known since 1977 to be made by osteoblast cells, but it had no known function."

However, the team found a novel function of the molecule.

Usually, an increase in insulin levels in the blood is accompanied by a decrease in insulin sensitivity.

But the authors found osteocalcin boosted both the secretion and the sensitivity to insulin.

In mice, increasing the activity of the molecule stimulated pancreatic cells to produce more insulin and at the same time directed fat cells to release a hormone called adiponectin - which improves insulin sensitivity.

It also stimulated the production of the insulin-producing cells themselves, which is currently considered to be one of the best, although unattainable, potential treatments for diabetes.

Increasing the activity of osteocalcin also prevented the development if type 2 diabetes and obesity in the mice, and mice who could make no osteocalcin had type 2 diabetes and increased fat mass.

New therapies

Professor Karsenty said: "The discovery that our bones are responsible for regulating blood sugar in ways that were not known before completely changes out understanding of the function of the skeleton and uncovers a crucial aspect of energy metabolism.

"These results uncover an important aspect of endocrinology that was unappreciated until now."

And the finding could provide a new therapeutic target to help treat diabetes in humans too, as people with type 2 diabetes have been shown to have low osteocalcin levels.

The researchers will now investigate the role of osteocalcin in regulating blood sugar in humans.

Matt Hunt, Science Information Manager at Diabetes UK, said: "This is a very interesting study.

"Diabetes research has never previously proposed the idea of the skeleton being involved in the development of diabetes.

"This could potentially open up a whole new area of research."

He said the research could led to an improved understanding of the causes of diabetes, but warned further research was needed to establish a conclusive link between osteocalcin and diabetes.