Kidney Disease Can Lead to Diabetes, Not Just the Other Way Around

Kidney disease increases the risk for diabetes, a new study finds. Medical experts already knew that the reverse is true – that diabetes increases the risk for kidney disease. The authors of the new study, though, found that kidney dysfunction can lead to diabetes – and, that a waste product called urea plays a role in the two-way link between the two diseases.

Urea comes from the breakdown of protein in food. Kidneys normally remove urea from the blood, but poor kidney function can lead to increased levels of urea.

The study involved the analysis of medical records over a five-year period for 1.3 million adults who did not have diabetes. About 9% had elevated urea levels, a sign of reduced kidney function. That’s the same rate as in the general population, according to the researchers.

People with high urea levels were 23% more likely to develop diabetes than those with normal urea levels, the study found. The results were published online recently in the journal Kidney International.

“The risk difference between high and low levels is 688 cases of diabetes per 100,000 people each year,” said study senior author Dr. Ziyad Al-Aly. He’s an assistant professor of medicine at Washington University School of Medicine in St. Louis.

“When urea builds up in the blood because of kidney dysfunction, increased insulin resistance and impaired insulin secretion often result,” Al-Aly said.

The findings about the role of urea could help in efforts to improve treatment and possibly prevent diabetes, the researchers said. Urea levels can be lowered in a number of ways, including medication and diet.



My Take:
The blood tests used in this study was the BUN (blood urea nitrogen), part of the CMP (comprehensive metabolic profile) – standard fasting blood tests. Included in the CMP for the past few years is another test, the eGFR (estimated glomerular filtration rate).

The GFR shows kidney impairment long before the BUN typically elevates. A level of 90 or greater indicates normal kidney function. Levels between 60 and 90 indicate impaired kidney function without kidney damage. Levels below 60 indicate kidney damage. Unfortunately, most physicians ignore test results between 60 and 90 and some labs only report the test results as >60 and do not flag the test as abnormal.

I typically treat a GFR lower than 90 with Arginase. This is an enzyme that converts ammonia to urea. Arginase will often raise the GFR significantly over the course of a couple of months.

Medication is the most common cause of a low GFR, with hypertensive drugs and diuretics leading the list. However, much like this study, clinically, I have seen a strong correlation between a low GFR and a high A1c (pre-diabetes). In fact, all aspects of metabolic syndrome appear to correlate with a low GFR.

The Bottom Line:
Look at your most recent fasting lab work. (I recommend running the CMP as part of a larger profile every year.) If your GFR is below 90 talk to your PCP (primary care physician). If they ignore the test, seek qualified nutritional counsel. Compare your GFR with the A1c, TSH (thyroid stimulating hormone), fasting glucose and serum lipids. Any of these markers are red flags for metabolic syndrome and must be addressed.

Source: December 26, 2017 National Institutes of Health