Diabetic Neuropathy: Distribution Pattern Revisited

It is not well known which of the common neuropathic distribution patterns in diabetes might suggest underlying mechanisms. To examine this question, we present data from a nerve conduction study (NCS). Irrespective of symptoms, we enrolled 323 type 2 diabetic patients (206 men, 117 women; mean age 64.1 years [51-79]; duration 12.0 years [5-19]; HbA1C 8.7% [5.1-12.1]; half [n = 142] untreated). NCS was performed for the following patterns: mononeuropathy (unilateral [MNU], bilateral [MNB]), multiple mononeuropathy (MMN), and polyneuropathy (PN). In 266 patients, we performed atherosclerosis tests: cardio-ankle vascular stiffness index (CAVI) and carotid ultrasonography. Neuropathy was observed in 235, and in 88 it was not observed; the latter then served as the control group. The most common pattern was MMN (26%), followed by MNB (18%), PN (16%), and MNU (12%). A combination of demyelination and axonal damage was revealed. Longer duration of diabetes compared with controls (8.6 years) was associated with MNB (12.5 years), MMN (14.8 years), and PN (17.4 years) (p < 0.05). HbA1C was associated with PN (p < 0.05). Atherosclerosis risks were associated with MNB, MMN, and PN (p < 0.05). Our study results indicated that (multiple) mononeuropathy is the most common distribution pattern in diabetes.