Felis ISSN 2398-2950

Diabetes: neuropathy

Contributor(s): David Morgan

Introduction

  • Very common complication in human diabetics and, although probably most common long term complication in cats, is a relatively infrequent occurrence in this species.
  • Cause: nerve damage secondary to diabetes mellitus Diabetes mellitus (DM).
  • Signalment: mature to older (with chronic DM).
  • Signs: hindlimb wasting and weakness.
  • Diagnosis: concurrent neurological signs and DM.
  • Treatment: manage DM but no specific therapy for nerve injury.
  • Prognosis: may show neurological improvement with successful treatment of DM.

Pathogenesis

Pathophysiology

  • Late diabetic complications are the result of damage to tissues such as nervous tissue which do not require insulin in order to take up glucose. These are therefore exposed to high concentrations of glucose in the long term.
  • As glucose builds up in these tissues unmetabolized it is shifted into a sorbitol pathway  →  sorbitol. The sorbitol is more slowly converted to fructose.
  • As this conversion takes place NAD (nicotinamide adenine dinucleotide) is reduced to NADH (nicotinamide adenine dinucleotide phosphate)  →  changes in lipid metabolism, increase in free radicals, and increased nitric acid production.
  • Depletion of myo-inositol decreases sodium ATPase activity reducing transmembrane sodium gradient  →  slowing nerve conduction.
  • High levels of glucose also permits non-specific glycosylation of proteins and since proteins are involved in almost every biological process these changes can have far-reaching effects:
  • May affect myelin and promote myelin uptake by macrophages leading to demyelination of nerves.
  • Glycosylation of tubulin may cause cross-linking and tubulin aggregate formation leading to nerve injury.
  • Local vasoconstriction may contribute to nerve hypoxia due to reduced blood flow.

Timecourse

  • More likely to develop with poor glycemic control.
  • May develop years after onset of DM (even if this is diagnosed and treated correctly).

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Shell L G (1995) Diabetic polyneuropathy. Feline Pract 23 (2), 27 PubMed.
  • Towell T L & Shell L C (1994) Endocrinopathies that affect the peripheral nerves of cats and dogs. Comp Cont Ed 16 (2), 157-161 VetMedResource.
  • Kranek B, Moise N, Cooper B et al (1984) Neuropathy associated with diabetes mellitus in the cat. JAVMA 184 (1), 42-45 PubMed.


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