Diabetic neuropathy - Complications of diabetes

Diabetic neuropathy

Definition

Nerve damage is one of the microvascular complications of diabetes mellitus.

Incidence/prevalence

Diabetes is the most common metabolic disorder causing neuropathy: 10% of diabetics have significant symptoms and 30% have evidence on testing.

Aetiology

It is thought to be secondary to hyperglycaemia and microvascular disease.

There are three main types of diabetic neuropathy:

·        Symmetrical peripheral neuropathy: Affecting sensory and motor function diffusely, particularly in the lower limbs. This can be a painful neuropathy.

·        Focal and multifocal neuropathy: Affecting one or more cranial or peripheral nerves.

·        Autonomic neuropathy: Affecting the sympathetic and parasympathetic nerves.

Pathophysiology

Hyperglycaemia may damage nerves through non-enzymatic glycosylation of proteins or through the accumulation of sorbitol in nerve cells, which can take up glucose without the aid of insulin.

Microvascular damage (which itself is thought to be secondary to hyperglycaemia and other factors) to the capillaries which supply nerves probably cause is-chaemic nerve damage. Focal nerve palsies may be due to sudden occlusion of a larger vessel causing infarction.