Diabetes effect on Nervous System Part I, Diabetic Neuropathy



What is diabetic neuropathy ?

When the nerves are affected by diabetes, a person is said to have diabetic neuropathy. Possibly the commonest long term complication of diabetes, the biggest problem is that in many patients the signs that they have diabetic neuropathy are so subtle, that it’s presence only comes to light when the patient comes with a complication caused by the nerve disorder, such as a foot ulcer, etc.

People with diabetes can develop nerve problems at any time. Significant clinical neuropathy can develop within the first 10 years after diagnosis of diabetes and the risk of developing neuropathy increases the longer a person has diabetes. Some recent studies have reported that:

You can check your diabetes at home easily

  • 60 percent of patients with diabetes have some form of neuropathy, but in most cases (30 to 40 percent), there are no symptoms.
  • 30 to 40 percent of patients with diabetes have symptoms suggesting neuropathy, compared with 10 percent of people without diabetes.

To compound the difficulty of detecting it, diabetic neuropathy itself has a slow and insidious onset. Patients often say that they were at first unaware of growing numbness in their feet and hands.

You can now consult with a Super Specialist Doctor from your home or office

But it is absolutely essential that you must have yourself tested for neuropathy, as diabetic nerve disease can lead to many serious complications.


To understand this, let us briefly consider the role played by the nerves.

What does my nervous system do?

Tasting, smelling, seeing, hearing, thinking, dreaming, breathing, heart beating, moving, running, sleeping, laughing, singing, remembering, feeling pain or pleasure, painting, writing…you couldn’t do any of these things without your nervous system!

Made up of your brain, your spinal cord, and an enormous network of nerves that thread throughout your body, it’s the control center for your entire body. Your brain uses information it receives from your nerves to coordinate all of your actions and reactions. Without it, you couldn’t exist!

That’s how important your nervous system is.

It is the nerves which make up the peripheral nervous system which carry messages back and forth between the brain and other parts of the body.

What are nerves?

They’re the thin threads of nerve cells, called neurons that run throughout your body. Bundled together, they carry messages back and forth just the way that telephone wires do. Sensory nerves send messages to the brain and generally connect to the brain through the spinal cord inside your backbone. Motor nerves carry messages back from the brain to all the muscles and glands in your body.

So how do they pass along messages?

Through the marvels of chemistry and a kind of electricity! Neurons are thin. Some are very small, and some can be three feet long! All are shaped somewhat like flat stars which have, to varying degrees, been pulled at each end so that they have long fingers. The fingers of one neuron almost reach to the next neuron.

When a neuron is stimulated — by heat, cold, touch, sound vibrations or some other message — it begins to actually generate a tiny electrical pulse. This electricity and chemical change travels the full length of the neuron. But when it gets to the end of finger-like points at the end of the neuron, it needs help getting across to the next extended finger. That’s where chemicals come in. The electrical pulse in the cells triggers the release of chemicals that carry the pulse to the next cell. And so on and on till it reaches its destination. Impulses travel through the nerve network to the brain at a rate of 350 feet per second!

It takes the corporation of three system to carry out the mission of the nervous system . They are the central, the peripheral nervous systems.

The central nervous system has the responsibility for issuing nerve impulses and analyzing sensory data, and includes the brain and spinal cord.

The peripheral nervous system is responsible for carrying these nerve impulses to and from the body.

The peripheral nervous system is subdivided into the

  • sensory-somatic nervous system and the
  • autonomic nervous system

Whilst some divide the nerves in the body into the peripheral nervous system and those in the autonomic nervous system, today, most feel that that one should use the term Peripheral Nervous System for all the nerves not considered to be part of the central nervous System, and then divide these into the Sensory-Somatic Nervous System ( what has popularly been called the peripheral nervous system in the past) and the Autonomic Nervous System.

This helps to describe their functions better.

The somatic nervous system consists of peripheral nerve fibers that send sensory information to the central nervous system AND motor nerve fibers that project to skeletal muscle.

The autonomic nervous system is composed of the sympathetic and parasympathetic systems and is responsible for regulating and coordinating the functions of vital structures in the body

How can diabetes hurt my nervous system?

Whilst we still do not know the exact way by which diabetes affects the nerves, everyone is agreed that having high blood glucose levels can not only damage the nerves themselves, but also affect the small blood vessels which carry nourishment to the nerves.

Damaged nerves may stop sending messages. Or they may send messages too slowly or at the wrong times.

The Sensory-Somatic Nervous System

The Sensory-Somatic nerves go from your spinal cord to your arms, hands, legs, and feet.

The Sensory-Somatic Neuropathy can be of three types and more than one type can often be present at the same time.

a) Diffuse neuropathy;
b) Focal neuropathy;
c) “Burning” neuropathy

Diffuse Neuropathy

The most common type of diabetic neuropathy damages the nerves of the limbs, especially the feet. Nerves on both sides of the body are affected. Common symptoms of this kind of neuropathy are:

  • Numbness or insensitivity to pain or temperature
  • Tingling, burning, or prickling
  • Sharp pains or cramps
  • Extreme sensitivity to touch, even light touch
  • Loss of balance and coordination.

These symptoms are often worse at night.

Damage to sensory-somatic nerves can make your arms, hands, legs, or feet feel numb. Also, you might not be able to feel pain, heat, or cold when you should. You may feel shooting pains or burning or tingling, like “pins and needles.” These feelings are often worse at night. They can make it hard to sleep. Most of the time these feelings are on both sides of your body, like in both of your feet. But they can be on just one side.

The symptoms of diabetic neuropathy vary. Numbness and tingling in feet are often the first sign. Some people notice no symptoms, while others are severely disabled. Neuropathy may cause both pain and insensitivity to pain in the same person. Often, symptoms are slight at first, and since most nerve damage occurs over a period of years, mild cases may go unnoticed for a long time. In some people, mainly those afflicted by focal neuropathy, the onset of pain may be sudden and severe.

The damage to nerves often results in loss of reflexes and muscle weakness. The foot often becomes wider and shorter, the foot muscles get weak and the tendons in the foot get shorter. The gait may change, and foot ulcers appear as pressure is put on parts of the foot that are less protected. Because of the loss of sensation, injuries may go unnoticed and often become infected. If ulcers or foot injuries are not treated in time, the infection may involve the bone and require amputation. However, problems caused by minor injuries can usually be controlled if they are caught in time. Avoiding foot injury by wearing well-fitted shoes and examining the feet daily can help prevent amputations.

Focal Neuropathy

Occasionally, diabetic neuropathy appears suddenly and affects specific nerves, most often in the torso, leg, or head. Focal neuropathy may cause:

  • Pain in the front of a thigh
  • Severe pain in the lower back or pelvis
  • Pain in the chest, stomach, or flank
  • Chest or abdominal pain sometimes mistaken for angina, heart attack, or appendicitis
  • Aching behind an eye
  • Inability to focus the eye
  • Double vision
  • Paralysis on one side of the face (Bell’s palsy)
  • Problems with hearing.

This kind of neuropathy is unpredictable and occurs most often in older people who have mild diabetes. Although focal neuropathy can be painful, it tends to improve by itself after a period of weeks or months without causing long-term damage.

Painful Neuropathy

Although diabetic nerve damage usually leads to a loss of sensation in the limbs, a few patients can present with severe painful ( “burning”) symptoms. 4-7% of patients with diabetes suffer chronic, often distressing symptoms of severe pain, and irritating “pins and needles” in their feet.

Why do these patients react differently to diabetic nerve damage? This question is yet to be fully answered. People with poorly controlled diabetes for a long time are more likely to get chronic painful neuropathy. However, many patients with relatively well controlled diabetes also develop it, especially if the blood glucose levels have been brought down too rapidly especially when associated with a very low calory diet.

Painful symptoms can be transient, eg less than 12 months duration. Once symptoms have persisted for more than 12 months, they are less likely to disappear on their own. Although good blood glucose control is important for many reasons, striving for very tight blood glucose control is less likely to make the painful symptoms get better when they have been present for this length of time.

Commonly reported symptoms include:

Burning, feeling like the feet are on fire Freezing, like the feet are on ice, although they feel warm to touch
Stabbing, like sharp knives Lancinating, like electric shocks

People with painful neuropathy may also complain of:

  • Allodynia which means feeling pain from a stimulus that would not normally be painful. An example of this is wearing shoes or having bed sheets touching the feet
  • Hyperalgaesia which means having an exaggerated response to a stimulus which is normally painful. This is often seen in response to heat
  • a feeling of tightness or pressure around the feet
  • vibration or tingling sometimes described as ants crawling under the skin

The autonomic nervous system controls smooth muscle of the viscera (internal organs) and glands.

By understanding the important role played by the nerves, one can well realize the importance of the problems that can arise when these nerves cannot function properly when damaged by diabetes.

Whilst, diabetes can affect the Central Nervous System (CNS), it is the Peripheral Nervous System (PNS) which has been the focus of diabetic neuropathy.

In the next part II treatment will be discussed and also the effect on various other systems like cardiac system and sexual dysfunction like to diabetic neuropathy will be discussed. 


About Anuj Agarwal

I am a professional with varied working experience of more than 18 years in India, USA and Middle East. My areas of work and interest are Information Technology, Corporate Social Responsibility, Health and Wellness. Please feel free to contact me through the blog or write me at agarwalanuj@yahoo.com
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One Response to Diabetes effect on Nervous System Part I, Diabetic Neuropathy

  1. Pingback: Diabetes effect on Nervous System Part I, Diabetic Neuropathy « healthsewak.com

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