When a person’s blood sugar is higher than normal, but not high enough to be classified as Type 2 diabetes, that person is said to have prediabetes. Prediabetes is viewed as a warning sign that you could develop Type 2 if you don’t make some lifestyle changes. But a new study from the Johns Hopkins University School of Medicine indicates prediabetes might be more damaging to motor nerves than once believed. The study also suggests the conventional view of how nerves deteriorate might need to be revised.
The study, which was conducted over a three-year period, assessed 62 participants; 52 of them had small fiber neuropathy, a disorder that affects the small nerves that terminate at the skin’s surface. People with this condition commonly experience tingling sensations that begin in the feet and then travel upward. The remaining 10 participants were healthy controls.
Of the 52 participants with small fiber neuropathy, 13 had prediabetes and 14 had Type 2 diabetes. The remaining 25 had normal blood sugar levels, and the cause of their small fiber neuropathy was unknown. The volunteers ranged in age from their mid-40s to their late 60s; just over half were male.
At the beginning of the study, the researchers took skin samples from the ankle, the lower thigh, and the upper thigh. Three years later, they took the same samples again. As expected, the skin samples taken at the beginning of the study from people with diabetes showed nerve damage, but the researchers were surprised to also find nerve damage in those who had prediabetes. And the people with prediabetes continued to lose nerve fiber density over the course of the study. That was the first surprise. Michael Polydefkis, MD, one of the researchers, said, “I expected that people with diabetes would do worse, but I didn’t really expect people with prediabetes to experience a similar rate of degradation of their small nerve fibers.”
The second surprise was that the participants with small fiber neuropathy exhibited deterioration over the entire length of their nerves, not just at the nerve ends as the researchers had expected. The researchers cautioned that the study involved only a small number of people and that factors other than diabetes might have contributed to their nerve damage, such as high blood pressure, high cholesterol, and smoking. Follow-up research will be needed to verify the study’s findings.
Nevertheless, the research underscores the need to take prediabetes seriously. Said Polydefkis, “I liken small fiber neuropathy to the canary in the coal mine. It signals the beginning of nerve deterioration that with time involves other types of nerve fibers and becomes more apparent and dramatically affects people’s quality of life. The results of this new study add urgency to the need for more screening of those with the condition and faster intervention.”
This blog entry was written by Joseph Gustaitis, a freelance writer and editor based in the Chicago area.