Impact of microangiopathy on chronic symptomatic peripheral neuropathy

The role of microvascular disease in the aetiology of diabetic peripheral neuropathy remains controversial. Muscle capillary basement membrane thickening (MCBMT) and increased albumin excretion rates (AER) are features of generalized diabetic microangiopathy and may relate to the severity of neuropathy. We have studied 19 patients with neuropathy of greater than 12 months duration and assessed relationships between the severity of neuropathy and MCBMT, AER, presence of retinopathy, age and duration of diabetes. Nine patients had retinopathy and 10 did not. The two groups of patients were well matched for age, type of diabetes and HbA1% but diabetic patients with retinopathy had significantly longer duration of diabetes (median duration 22 yr, range 3-42 yr compared with patients without retinopathy (6 yr range 1-20 yr p less than 0.05). The group with retinopathy had significantly greater median MCBMT 3,077 A (range 741-10,732 A) than their age matched non-diabetic controls 2,256 A (1,290-4,406 A p less than 0.02) or the 10 diabetic patients without retinopathy 1,599 A (805-5,152 A). The patients with retinopathy also had greater median AER 88 micrograms/min (range 8-200 micrograms/min) compared with patients without retinopathy 8 micrograms/min (2-63 micrograms/min p less than 0.05), and had significantly more severe neuropathic features on a 12 point neurophysiological ranking scale (p less than 0.05). This study showed an association between retinopathy and severity of neuropathy but there were no associations between severity of neuropathy or AER with MCBMT. Severe chronic peripheral neuropathy is associated with microangiopathic complications.