LONDON - An international research team has pinpointed a genetic mutation that can raise a healthy person's blood sugar to harmful levels, putting them at higher risk of serious problems like heart disease.

The defect could cause an increase of around 5 percent that can prove dangerous even for people without diabetes, the researchers reported in the journal Science said on Thursday.

Too much glucose in the blood can damage the eyes, kidneys and nerves, and also lead to heart disease, stroke and limb amputations. It is also a sign of diabetes, though the findings did not link the gene directly to the disease.

"Our study helps unravel the genetic reasons why some people have higher levels of glucose in their blood than others," said Philippe Froguel, a researcher at the French National Research Institute and Imperial College London, who led the study.

"We hope that ultimately our research will mean we can develop new treatments to stop people from developing high blood glucose levels."

The research associating high glucose levels to the gene known as G6PC2, or IGRP, showed that the mutated version blocks a protein called glucokinase from doing its job of tightly regulating glucose, causing blood sugar to rise.

Glucokinase works by signaling to cells known as beta cells which then secrete insulin to keep blood glucose levels under control, the researchers said.

In their study, Froguel and colleagues compared the genetic makeup of 654 non-diabetics with glucose levels that ranged from the low to the high end of what is considered normal.

Next they scanned more than 392,000 mutations to find ones specific to high blood glucose levels. They confirmed their findings by analyzing the genes of a further 8,000 people with normal blood sugar levels.

"Having a high level of blood glucose is a bit like having high cholesterol or high blood pressure in that the higher the level, the greater your risk of serious health problems," Froguel said in a statement.

The findings come from the same team which last year identified five areas of DNA that could account for 70 percent of the genetic risk for type 2 diabetes.