Evaluation of Neuropathy in Diabetes
Abstract & Commentary
By Norman Latov, MD, PhD, Professor of Neurology and Neuroscience, Director, Peripheral Neuropathy Center, Weill Medical College of Cornell University. Dr. Latov is a consultant for Quest Diagnostics and Talecris Biotherapeutics, Inc., is a stockholder for Therapath LLC, and has royalties in Athena Diagnostics.
Synopsis: Patients with diabetes that present with neuropathy need to be evaluated for other potential causes of neuropathy, in addition to the diabetes.
Source: Gorson KC, Ropper AH. Additional Causes for Distal Sensory Polyneuropathy in Diabetic Patients. J Neurol Neurosurg Psychiatry. 2006;77:354-358.
In a retrospective study of approximately 100 patients with distal symmetric neuropathy and diabetes that were evaluated at an academic referral center, 53% had other potential causes of neuropathy, with 25% having more than one additional cause. Other causes for neuropathy identified in this patient cohort, included neurotoxic medications, alcohol abuse, renal disease, monoclonal gammopathy, chronic inflammatory demyelinating polyneuropathy (CIDP), and deficiencies of vitamins B12, B1 or B6 Cao et al conclude that patients with diabetes who present with neuropathy cannot be presumed to have diabetes as the only cause of the neuropathy, and should be evaluated for other potential causes.
When evaluating a patient with diabetes and neuropathy, it is common to presume that the neuropathy is diabetic and that no further testing needs be done. However, as patients with diabetes can also develop other maladies, a certain percentage would be expected to have other causes for neuropathy, similarly to those without diabetes. In addition, diabetes can predispose to other conditions that can cause or contribute to the neuropathy, such as B12 deficiency resulting from metformin therapy or atrophic gastritis, other nutritional deficiencies associated with malabsorption, or CIDP. The figure of 53% may be higher than that seen in routine practice, possibly due to referral bias at a tertiary academic center, but the message still holds. Patients with diabetes need to be evaluated for other potential causes of neuropathy, particularly if the presentation is atypical or the neuropathy progresses despite optimal glycemic control.