Individuals with the trait aren't immune from the conditions, researchers say, but a study of nearly 7,900 subjects found that they are as much as 48 percent less likely to suffer from either illness.

"This gives us insight into how heart disease and diabetes may develop," said co-author Eric Rimm, an associate professor of epidemiology and nutrition at the Harvard School of Public Health in Boston.

Scientists don't think diabetes and heart disease are inherited, but genes can play a major role, they say. "We do know there are genes that make people more susceptible to becoming diabetic if they're exposed to the right environmental factors," Rimm said. Specific genes have also been linked to heart disease.

In mice, a gene variation appears to provide protection against type 2 diabetes and clogged arteries. In the new study, Rimm's team examined the medical and genetic records of 7,899 people to see if the variation did the same thing for humans.
The study findings appear in this week's issue of the Proceedings of the National Academy of Sciences.

A total of 4.3 percent of the people studied had one copy of the variant gene, Rimm said.

These people appear to have won a kind of genetic lottery, because levels of triglycerides -- a potentially dangerous type of blood fat -- were 12 percent lower in their blood than in the other subjects. Their risk of heart disease was also 34 percent lower, and if they were obese, their risk for type 2 diabetes was 48 percent less than that of obese individuals who did not carry the gene variant.

Rimm suspects that the genetic variation helps control molecular signals that influence how triglycerides circulate in the blood.
What next? It's possible that a better understanding of the genetics of diabetes and heart disease could lead to more effective treatments, Rimm said. "If you could emulate what this form of this gene is doing, maybe you could lower someone's risk of heart disease or diabetes by copying the same type of physiological effects," he added.

The research raises another possibility: genetic tests that could alert people if they have a higher likelihood of getting diabetes later in life.

Ideally, "if you know in advance that you're at risk, that would make people think and give them the opportunity to protect themselves," said Dr. Larry C. Deeb, the American Diabetes Association's president-elect of medicine and science. After all, he said, diabetes is largely preventable.

Source: Diabetes In Control