Nerve symptoms can begin before anyone tells you that you have diabetes, and there are two separate reasons for that. The first is that a lot of diabetes is simply not yet identified: the CDC estimates that 27.6% of US adults aged 18 and older who have diabetes are undiagnosed, which is about 11.0 million people [1]. The second is that nerve injury is reported in people whose glucose handling is impaired but has not crossed the diabetes threshold [2].
Key takeaways
- An estimated 27.6% of US adults with diabetes do not know they have it, roughly 11.0 million people, based on 2023 data [1].
- An estimated 115.2 million US adults aged 18 and older have prediabetes [1].
- Peripheral neuropathy has been reported more frequently in people with impaired glucose tolerance than in people with normal glucose tolerance [2].
- About 20% of people with type 2 diabetes already have diabetic peripheral neuropathy at the time the diabetes is diagnosed [2].
- Neuropathy is a category, not a diagnosis. Glucose is one driver among several, and more than one is often active at once.
- Reduced protective sensation is a safety problem before it is a comfort problem. Daily foot checks start now, not after testing.
Why the timeline is confusing
People reasonably assume the sequence runs diagnosis first, complications later. In practice the metabolic changes precede the label, sometimes by years, and the label arrives when someone happens to run the right test.
That is why “my sugar was normal” is a weaker reassurance than it sounds. It describes one measurement on one day, and the CDC estimate of 11.0 million US adults with undiagnosed diabetes shows how often the measurement has simply not been made [1].
What the prediabetes research actually reports
A 2017 review in the Journal of Diabetes Investigation examined peripheral neuropathy in prediabetes and the metabolic syndrome. It reports that neuropathy has been found more often in people with impaired glucose tolerance than in people with normal glucose tolerance, drawing on population studies that examined all three groups [2].
The same review notes that roughly 20% of people with type 2 diabetes already have diabetic peripheral neuropathy at the point the diabetes is diagnosed [2]. Nerve involvement is not a late complication in those cases; it is present at the start.
What this does not establish is a threshold below which nerves are safe. It establishes that glucose handling short of diabetes is worth taking seriously when someone has foot symptoms.
What happens around the nerve
Peripheral nerves are supplied by very small blood vessels and depend on steady oxygen delivery and stable metabolic conditions. Both of those can be disturbed while a person is still described as not diabetic.
Glycation
Glucose reacts with proteins over time, and the products of that reaction accumulate in tissue. This is the chemistry behind how sugar damages nerves, and it does not switch on at a diagnostic cutoff.
Perfusion and metabolic strain
Nerve tissue has a high energy demand relative to its blood supply. When delivery and demand stop matching, the longest fibers, the ones reaching the toes, are the first to show it, which is why symptoms usually start at the feet.
Symptoms worth taking to a clinician
The pattern matters more than the intensity. What people describe most often is burning at night, pins and needles, numbness that spreads slowly upward from the toes, or a sense that the foot is less responsive than it used to be.
Numbness is a safety issue first
Loss of protective sensation means a blister, a seam, a pebble or a burn can go unnoticed until the skin has broken down. Check both feet daily, including between the toes and across the soles, and use a mirror or a second pair of eyes if you cannot see them easily.
Any open area, or a foot that is hot and swollen, needs evaluation rather than observation.
Glucose is one driver, not the whole list
Even when glucose handling is clearly involved, it is rarely the only thing acting on the nerve. A work-up that stops at the metabolic answer will miss the contributors that are easiest to correct.
- Nutritional, including B12 status and malabsorption after gastrointestinal surgery.
- Autoimmune and inflammatory, including gluten-related and connective tissue processes.
- Toxic, including alcohol, heavy metal exposure and medication effects such as chemotherapy.
- Structural, including nerve entrapment and spine-related contributions.
How the evaluation is sequenced at Regenerve
The order is deliberate: establish the symptom pattern, then measure, then decide. Electrodiagnostic testing (EMG/NCS) is performed on site and characterizes conduction in the larger nerve fibers.
When the story is burning and temperature change rather than numbness and weakness, the small fibers are the likely target, and conduction studies are not the right instrument for that. We use in-office small-fiber and vascular assessment in those cases, alongside metabolic and nutritional evaluation.
What care addresses, and what it does not promise
Regenerve offers class 4 photobiomodulation, class 3B cold laser, whole-body infrared and metabolic and nutritional care as components of a plan built around the identified driver. Orthobiologic injections such as PRP and BMAC are offered in selected situations.
We do not promise nerve regeneration, reversal, and we do not publish success percentages for our protocols.
Frequently asked questions
Can nerve damage start before diabetes is diagnosed?
It can. A review of peripheral neuropathy in prediabetes and the metabolic syndrome reports that neuropathy has been found more often in people with impaired glucose tolerance than in people with normal glucose tolerance, and that roughly 20% of people with type 2 diabetes already have diabetic peripheral neuropathy when the diabetes is first identified. See how blood sugar damages nerves.
My A1c is normal. Does that rule out a metabolic cause?
Not by itself. A single value in the normal range describes that moment rather than the years behind it, and glucose is only one of several metabolic inputs a nerve depends on. The more useful question is what else is on the list. See the hidden drivers of peripheral neuropathy.
What else causes neuropathy when blood sugar looks fine?
Nutritional, autoimmune, toxic and structural causes all produce foot symptoms that resemble the metabolic pattern, and more than one is often present at the same time. B12 status is one of the first to check because it is common, testable and correctable. See functional B12 deficiency and neuropathy.
Should I be checked for celiac disease or gluten sensitivity?
It belongs in the work-up when the pattern does not fit a length-dependent metabolic neuropathy, or when digestive symptoms sit alongside the nerve symptoms. Standard screening does not close the question in every case. See the gluten and neuropathy connection.
My feet are numb. What should I be doing at home right now?
Check both feet daily, including between the toes and the soles, because reduced protective sensation means an injury can go unnoticed until it is infected. Use a mirror or ask someone to look, and get any open area or hot, swollen foot evaluated rather than watched. See small fiber neuropathy symptoms and testing.
Start with the Nerve Damage Score
The entry point at Regenerve is the free five-question Nerve Damage Score. It takes a few minutes, and it tells us which driver to look at first so your visit starts with a plan instead of a guess.
Take the free Nerve Damage Score assessment, then bring the result to a physician-led visit at Regenerve, 4477 Woodson Rd #104, St. Louis, MO 63134, minutes from St. Louis Lambert International Airport. We see patients from the St. Louis region, Missouri and Illinois.
Sources
- Centers for Disease Control and Prevention. National Diabetes Statistics Report, updated January 21, 2026 (2023 data). https://www.cdc.gov/diabetes/php/data-research/index.html — referenced for the estimate that 27.6% of US adults aged 18 or older with diabetes are undiagnosed, representing 11.0 million people, and for the estimate of 115.2 million US adults aged 18 or older with prediabetes.
- Stino AM, Smith AG. “Peripheral neuropathy in prediabetes and the metabolic syndrome.” Journal of Diabetes Investigation, 2017. https://pmc.ncbi.nlm.nih.gov/articles/PMC5583955/ — referenced for the higher reported frequency of neuropathy in people with impaired glucose tolerance compared with people with normal glucose tolerance, and for the finding that approximately 20% of people with type 2 diabetes have diabetic peripheral neuropathy at the time of diagnosis.