Neuropathy is one of the many complications of both type 1 and type 2 diabetes mellitus, along with retinopathy, nephropathy, coronary heart disease, peripheral vascular disease, stroke and other sequelae of macrovascular and microvascular pathology. The financial toll exerted by diabetes in the US alone is over $132 billion per annum, half of which is attributable to diabetic complications.¹

• Type 1 diabetes accounts for about 10% of the diabetic population; it often, but not always, presents in childhood or adolescence and is an autoimmune disease with destruction of the pancreatic beta cells that manufacture insulin.

• Type 2 diabetes, accounting for about 90% of diabetic cases, is common in most high-income countries and is increasing in prevalence.² For example, in the population-based Framingham Heart Study, the eight-year incidence in middle-aged adults doubled (in women from 2.0% to 3.7%, in men from 2.7% to 5.8%) from the 1970s through the 1990s, mostly in those with a body mass index >30 kg/m², suggesting the contributions of a sedentary lifestyle and poor nutritional choices.³ Type 2 diabetes is felt to be the consequence of metabolic dysregulation resulting in insulin resistance; patients generally produce large amounts of insulin, but their cells become less and less responsive to insulin over time, until the native insulin production cannot maintain blood glucose control. The result is hyperglycaemia, which triggers disruption of several metabolic pathways,^4,5 forming reactive oxygen species which induce endothelial cell dysfunction and apoptosis of pancreatic islet cells and of peripheral neurons.

The frequency of neuropathy in diabetics depends on how the neuropathy is diagnosed—whether by clinical examination or incorporating one or more electrophysiological criteria. In a landmark study, following 4400 diabetic patients over 25 years (1947–73), Pirart⁶ found, using absent ankle reflexes and impaired vibration perception as the …