Stanford University researchers have identified genetic variations in a hormone involved in the secretion of insulin-a molecule that regulates blood sugar levels-that occur more frequently in some human populations than others.
People with the 'new' variants, which are thought to have first occurred 2,000 to 12,000 years ago, have higher fasting levels of blood glucose than those with the more traditional, or ancestral, form of the gene.
High blood glucose levels are associated with the development of diabetes, which occurs when the body is unable to produce or respond properly to insulin.
The finding may help scientists better understand the subtle changes in human metabolism, or "energy balance regulation," that occurred as our species shifted from being primarily hunter-gatherers to a more agriculturally based society.
It may also help clinicians identify individuals likely to develop diabetes, and direct the development of new therapies for diabetes and obesity.
"These studies are fascinating because it shows how much the selection process has affected human energy-balance regulation in just a few thousand years and how complex it could be for the future practice of personalized medicine," said Sheau Yu 'Teddy' Hsu, senior author of the study.
Hsu and his colleagues at Chang Gung Memorial Hospital in Taiwan and Texas A and M University first identified 207 genetic regions that have been associated with diabetes or obesity.
They then looked to see which of these had increased in prevalence in the time since humans began to move out of Africa about 60,000 years ago. They identified 59 genetic regions of particular interest, and homed in on those that occurred in at least 30 percent of people in the HapMap project - a worldwide survey of genetic differences among populations.
The research has been published in the journal Diabetes.