Approximately one half of peripheral neuropathy patients (people with pain and/or numbness in hands or feet) have diabetes as the cause of their condition. In addition, for the 25-33% of peripheral neuropathy patient’s who do not have a known cause to their symptoms, pre-diabetes accounts for upwards of 40% of these cases. The bottom line is that patient’s with peripheral neuropathy need to be screened for diabetes as well as pre-diabetes.
Diabetes is classically defined as having blood glucose above 125 milligrams per deciliter on three separate occasions, and an HbA1C above 6.4-6.7%. HbA1c is a marker used to see how high the person’s blood sugar has been over the last 3 months. It in essence tracks how much sugar is attached to a red blood cell, and because a red blood cell lives for 3 months, this allows us to see what the blood sugar has been over the last few months. Pre diabetes is defined as the individuals fasting glucose being between 100 to 125 mg/dL, and HbA1c above 6.0%, and an oral glucose tolerance test above 140 mg/dL after two hours. So what does all of this mean?
Diabetes and pre-diabetes are issues of blood sugar regulation. When we eat carbohydrates, for example a bagel, those carbohydrates are broken down into their individual building blocks, termed glucose. Glucose then enters from the gastrointestinal tract, into the blood stream. The pancreas is situated anatomically such that it is one of the first organs to be exposed to the blood coming from the gastrointestinal tract, giving it the opportunity to sample the quantity of sugar in the blood. Normally, as glucose levels rise in the blood stream, insulin is produced by the pancreas, in order for glucose to enter most cells of the body such as muscle tissue. Glucose once in the cell, provides the basic foundation for the cell to make energy.
Unfortunately, in pre-diabetes and diabetes, there is a trend towards the pancreas not being able to make enough insulin to coral the glucose coming into the blood stream from our diet. In pre diabetes the process starts as our cells become less responsive to insulin. As a result, if we eat that same bagel, we have to secrete more insulin to get the same amount of sugar into the cells. During this process, a point is reached at which not enough insulin can be produced on all occasions, such that blood sugar may rise above what it should be after we eat. These elevated sugar levels can then draw water into the cells of our nerves, especially in our feet, the cells of our kidney’s and into our retina. Patients with pre-diabetes often have what is termed “Metabolic Syndrome” where their body mass index is elevated, they may have hypertension, unwanted belly fat in males and fat around the pelvis in females, and high cholesterol.
If this process is not halted, over time the pancreas is not able to produce the amount of insulin it once was able to, and therefore when we eat the bagel, we cannot produce enough insulin to coral the glucose. This is diabetes. Now, because there are excess amounts of blood sugar, more extensive damage occurs to the peripheral nerves(think feet and hands), kidneys and retina.
Early in this sequence of events, mentioned above as pre-diabetes, the mildly elevated blood sugar levels will draw fluid into namely the small fiber neurons (nerve cells) which are uncovered or poorly protected. These nerve fibers experiance pain, temperature sensation, and carry information regarding how large or small the blood vessels should be. This fluid accumulation will be greatest at night when the person is not on their feet, and the nerves will swell due to the high glucose levels, causing pain and or burning sensations. If the person’s examination findings are consistent with changes primarily in pain and temperature sensation, this is termed a small fiber peripheral neuropathy, and out of all the categories of polyneuropathy, this can be one of the most miserable to suffer with. If this process occurs for long enough, the high blood sugar levels will ultimately result in all nerve fiber types being involved. This can result in tingling, numbness, or burning pain.
I must say how exciting it is to work with patients with peripheral neuropathy. Using diabetes and pre-diabetes as an example, not only are these patients seeing improvements in sensation in their feet, often their symptoms are changing, and more importantly, they are getting their blood sugar under control through diet and at times supplementation. In essence they are forming habits to be far healthier for the rest of their lives.
The first step with any patient who is pre-diabetic or diabetic is to work with them on their diet. However, many patients are resistant to this as it takes incredible discipline, work, and diligence. When someone does not want to change their diet, then of course their MD will have to put them onto a medication or multiple medications to corral the issue which will still not solve the problem.
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