Diabetic Neuropathy

Diabetic neuropathy affects up to 50% of patients with diabetes mellitus. It encompasses several neuropathic syndromes, the most common being distal symmetrical polyneuropathy or “diabetic peripheral neuropathy” (DPN). Risk factors for DPN include poor glycaemic control and drivers of macrovascular disease , including hypertension and obesity. 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 nerve function decline in DPN has emerged. Painful DPN affects about a quarter 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) and anticonvulsants (e.g. pregabalin, gabapentin). The OPTION DM trial has recently shown that these first-line drugs (and their combinations) have equivalent efficacy. It also showed that maximal tolerated combination treatment provides better relief than maximum tolerated monotherapy. Second-line drugs include opioids only under specialist care and capsaicin 8% patch, with more refractory cases referred for high-frequency spinal cord stimulation. Diabetic autonomic neuropathy also results in considerable morbidity, reduced quality of life and increased mortality. It can involve cardiovascular, gastrointestinal, urogenital, pupillomotor, thermoregulatory and sudomotor functions. Although counselling and non-pharmacological interventions are of some use, more severely afflicted patients require pharmacological intervention.