Diabetic neuropathy is a very serious and quite common malady for those who have diabetes. But there hasn't been a good way to predict who would likely suffer from this illness. That is, until it was discovered that a common blood test for triglycerides – a well-known cardiovascular disease risk factor – could allow doctors to predict which patients with diabetes are more likely to develop neuropathy.
Triglycerides are a type of lipid, or fat, that the body makes from calories it doesn’t need immediately. Triglycerides are stored in fat cells until they are needed to provide energy. When higher-than-normal amounts circulate in the blood, a person is at higher risk of disease.
In a study now online in the journal Diabetes, University of Michigan and Wayne State University researchers analyzed data from 427 diabetes patients with neuropathy, a condition in which nerves are damaged or lost with resulting numbness, tingling and pain, often in the hands, arms, legs and feet. The data revealed that if a patient had elevated triglycerides, he or she was significantly more likely to experience worsening neuropathy over a period of one year. Other factors, such as higher levels of other fats in the blood or of blood glucose, did not turn out to be significant. The study will appear in print in the journal’s July issue.
Kelli A. Sullivan, Ph.D., co-first author of the study and a professor in neurology at the U-M Medical School, said “In our study, elevated serum triglycerides were the most accurate at predicting nerve fiber loss, compared to all other measures." Senior author, Dr. Eva Feldman, believes that these results set the stage for clinicians to be able to address lowering lipid counts with their diabetes patients with neuropathy as vigilantly as they pursue glucose control.
“Aggressive treatment can be very beneficial to patients in terms of their neuropathy,” says Feldman, who is also director of the A. Alfred Taubman Medical Research Institute and director of the Juvenile Diabetes Research Foundation Center at U-M for the study of complications in diabetes.
With a readily available predictor for nerve damage – triglycerides are measured as part of routine blood testing – doctors and patients can take proactive steps when interventions can do some good. People can reduce blood triglyceride levels with the same measures that reduce cholesterol levels: by avoiding harmful fats in the diet and exercising regularly.
Diabetic neuropathy affects around 60 percent of the 23 million people in the United States who have diabetes. It is a complication in both type 1 and type 2 diabetes. Until now, doctors have lacked an effective way to predict which diabetes patients are at greatest risk of neuropathy. Most often, the condition becomes evident when irreversible nerve damage has already occurred. Neuropathy is the leading cause of diabetes-related hospital admissions and amputations that are not secondary to trauma.
The new finding adds to an emerging picture of the close connections between cardiovascular disease and diabetes. Elevated triglycerides are one of the most common features of the lipid disorders found in patients with type 2 diabetes, by far the most common form of diabetes, says Rodica Pop-Busui, M.D., Ph.D., one of the study’s authors and an assistant professor in the metabolism, endocrinology and diabetes division of the Department of Internal Medicine at the U-M Medical School.
“Cardiovascular disease is the main cause of excess mortality among patients with diabetes. Research also has shown that the presence of neuropathy is an important predictor of these deaths,” says Pop-Busui.