Neuropathy in diabetes

Diabetic polyneuropathy affects 30–50% of patients with diabetes mellitus. It encompasses several neuropathic syndromes, the commonest being distal symmetrical polyneuropathy or ‘diabetic peripheral neuropathy’ (DPN). Risk factors for DPN include poor glycaemic control and drivers of macrovascular disease including hypertension. Strong evidence in humans and animals implicates nerve ischaemia as the cause of DPN. Despite several well-designed recent trials, no novel approved treatment with unequivocal effects on the decline in nerve function in DPN has emerged. Painful DPN affects 15–26% of those with diabetes, produces considerable disability, and is challenging to assess and manage. First-line therapies are tricyclic antidepressants, serotonin noradrenaline reuptake inhibitors (e.g. duloxetine) or anticonvulsants (e.g. pregabalin, gabapentin). Second-line drugs include opioids. Diabetic autonomic neuropathy also results in considerable morbidity, reduced quality of life and increased mortality. It may involve cardiovascular, gastrointestinal, urogenital, pupillomotor, thermoregulatory and sudomotor function. Although counselling and non-pharmacological interventions are of some use, more severely afflicted patients require pharmacological intervention.