A new study has revealed that beta cells-responsible for making insulin in the human body-do not replicate after the age of 30, indicating that scientists are closer to advancements in diabetes treatment.
Type 1 diabetes is caused by a loss of beta cells by auto-immunity while type 2 is due to a relative insufficiency of beta cells.
By using radioactive carbon-14 produced by above ground nuclear testing in the 1950s and '60s, researchers have determined that the number of beta cells remains static after age 30.
Bruce Buchholz of the Lawrence Livermore National Laboratory scientist and collaborators from the National Institutes of Health used two methods to examine adult human beta cell turnover and longevity.
Using LLNL's Center for Accelerator Mass Spectrometry, Buchholz measured the amount of carbon 14 in DNA in beta cells and discovered that after age 30, the body does not create any new beta cells, thus decreasing the capacity to produce insulin as a person ages.
Because DNA is stable after a cell has gone through its last cell division, the concentration of carbon 14 in DNA serves as a date mark for when a cell was born and can be used to date cells in humans.
"We found that beta cells turnover up to about age 30, and there they remain throughout life. The findings have implications for both type 1 and type 2 diabetes," said Buchholz.
Type 1 diabetes is an auto-immune disease in which the body attacks beta cells. Both genetic predisposition and environmental triggers that are poorly understood have been implicated in the disease development.
However, in Type 2 diabetes (often called adult onset diabetes) is common in older people whose ability to secrete sufficient insulin to regulate blood sugar deteriorates as they age and is often due to increased demand in obese people.
"It could be due to loss of beta cells with age. The body doesn't make new ones in adulthood and there might not be enough cells to control blood sugar," he said.
Buchholz said there is active research in stem cell therapies to replace lost beta cells for both types of diabetes.
"But with these new findings, it isn't clear how easy it will be to get the body to make more beta cells in adulthood, when it is not a natural process," he said.
The findings appeared in the Journal of Clinical Endocrinology and Metabolism.