CHICAGO, Dec. 11 (Xinhua) -- Diabetes is known to increase a person's risk of kidney disease. Now, the converse is also true: Kidney dysfunction increases the risk of diabetes, according to a study of Washington University School of Medicine in St. Louis.
Researchers further deduced that a likely culprit of the two-way relationship between kidney disease and diabetes is urea, the nitrogen-containing waste product in blood that comes from the breakdown of protein in foods. Kidneys normally remove urea from the blood, but it can build up when kidney function slows down.
Researchers examined medical records in national databases and evaluated the records of 1.3 million adults without diabetes over a five-year period, beginning in 2003.
A common blood test that measures the amount of urea nitrogen found in the blood showed that 117,000 of those without diabetes, or 9 percent, had elevated urea levels, signaling poor kidney function.
Overall, those with high urea levels had a 23 percent higher risk of diabetes. In each year studied, the researchers documented new cases of diabetes in 2,989 of every 100,000 people with low urea levels and 3,677 new cases of diabetes among those with high urea levels.
"The risk difference between high and low levels is 688 cases of diabetes per 100,000 people each year," said the study's senior author Ziyad Al-Aly, an assistant professor of medicine at Washington University in St. Louis. "This means that for every 100,000 people, there would be 688 more cases of diabetes each year in those with higher urea levels."
In a mouse study published in the August 2016 Journal of Clinical Investigation, researchers induced kidney failure in mice. Subsequently, many of the animals experienced elevated urea levels, resulting in insulin resistance and impaired insulin secretion.
Al-Aly tested this in human. "Our results were almost an exact replica of the mouse study. The results showed a clear relationship between urea levels and risk of diabetes," he said.
The findings are significant because urea levels can be lowered through medication, diet and other means, thereby allowing for improved treatment and possible prevention of diabetes.
The study was published in Kidney International on Monday.