**2. Classification**

Table 1 gives a detailed classification of the neuropathies observed in diabetes.

© 2013 Conway and Peltier; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Medicine, and the American Association of Physical Medicine and Rehabilitation is, "a combination of neuropathic symptoms, multiple signs, and abnormal electrodiagnostic studies" [8]. However, this does not distinguish typical DSP from atypical diabetic neuropa‐ thies [1]. A more precise definition for typical DSP proposed by neuromuscular experts at the 2011 Neurodiab Meeting suggested a tiered approach of possible, probable, confirmed and subclinical DSP. Possible DSP includes symptoms or signs of DSP such as decreased distal sensation or depressed ankle reflexes. Probable clinical DSP includes a combination of symptoms and signs of DSP. Confirmed DSP includes symptoms, signs, and abnormal nerve conduction study consistent with DSP (i.e. symmetric). Subclinical DSP would include patients with abnormal nerve conduction studies but no signs or symptoms of neuropathy [1]. Debate is ongoing as to whether abnormal skin biopsy with decreased epidermal nerve fiber density

Diabetic Neuropathy

333

http://dx.doi.org/10.5772/55372

The prevalence of DSP in type 1 diabetes mellitus has been postulated to be over 50% by 25 years of diagnosis [9, 10]. These data depend on measures used for quantification. Nerve conduction studies are typically more sensitive than monofilament tests and often show decreased conduction velocity in sensory and motor nerves prior to the development of signs or symptoms of sensory loss with monofilament and vibration testing [11]. More tests used,

Risk factors for DSP incidence and severity in addition to duration of diabetes and age are hyperglycemia, systolic blood pressure, smoking, cholesterol, and height. The Diabetes Control and Complications Trial confirmed hyperglycemia as a significant risk factor for DSP

cohort studies of type 2 diabetes to delay progression in this population [12] which raises the

Typical progression of DSP in type 1 is very slow, with incremental sensory loss over years and decades. The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications study data show minimal changes in conduction velocity and amplitudes over 5 year periods, which can reassure patients [13, 14]. Progression typically affects both large, myelinated fibers conveying tactile sensitivity, vibration and joint position sense, and small, unmyelinated fibers conveying temperature and pain sensation. Motor involvement is typically subclinical until later in the disease course. While slowed conduction velocities, particularly in the fibular nerve, are common early signs of DSP, weakness typically

Inflammatory neuropathies such as mononeuritis multiplex and diabetic amyotrophy affecting the plexus are less common in type 1 diabetes than type 2 [15]. Chronic inflammatory demyelinating polyneuropathy is also more common in type 2, but has not been shown to

1 \*The DCCT was a groundbreaking study of patients with type 1 diabetes in the United States; a large, multicenter study designed to test whether improved glycemic control delayed the onset or progression of diabetic complications. The follow up epidemiologic study, EDIC (Epidemiology of Diabetes Interventions and Complications) continued to follow

question of whether hyperglycemia is the sole cause of DSP in type 2 diabetes.

occurs later, first affecting the toes and then more proximal muscles.

the same patients enrolled in DCCT, which is still ongoing.

. Interestingly, hyperglycemia alone has not been proven in prospective

should be considered with nerve conduction study as a confirmatory test.

and more sensitive measures will increase prevalence statistics.

**3.3. Epidemiology**

in type 1 diabetes1

**Table 1.** Classification of Diabetic Neuropathy
