Heterogeneity in diabetic distal neuropathy and differential approach to its treatment

AIMS: To determine the prevalence of painful diabetic neuropathy (PDN), to evaluate the composition and efficacy of pharmacotherapy and to develop a differential algorithm for symptomatic treatment of PDN.

MATERIALS AND METHODS: 4494 outpatient subjects participated in this study. Severity of pain syndrome was assessed with DN4 question- naire (supplemented with NTSS-9 scale) and visual analogue scale (VAS). After initial examination, a pharmacological evaluation of treatment was performed.

RESULTS: Based on our data, prevalence of diabetic neuropathy was estimated at 54%, with painful form reaching 6.4%. Median age was 57.2-12.1, duration of diabetes mellitus - 16.5-10.6 years. Type 1 / type 2 ratio equaled 32.4% : 67.6%, male/female - 29.7%: 70.3%. Median HbA_1c level was 8.4?1.6%. Ratio of chronic/acute forms of neuropathy was 267 : 20. Pain severity (as measured by VAS) distribution was as following: 15.6% ? severe, 40.6% ? moderate, 12.3% - mild, and 31.3% ? no pain symptoms. We did not find PDN to be associated with any parameters but sensory deficit (NTSS-9 and NDS: r=0.4; p <0.001). 21% of patients with chronic painful neuropathy (CPN) demonstrated allodynia and hyperalgesia besides typical symptoms. 97.9% of patients were previously treated with "pathogenetic" agents, 2.1% received anticonvulsants; overall efficiency was estimated at 22%. Patients with CPN and allodynia did not respond to treatment with alpha-lipoic acid (ALA), but pregabalin was efficient. After the examination treatment composition was adjusted as follows: treatment was ceased in 23% of patients, 11.9% received ALA, 53.6% - anticonvulsants, and 11.5% - antidepressants; overall efficiency was estimated at 75%.

CONCLUSION: Prevalence of PDN is relatively low. 15.6% of patients suffer from severe pain. Neuropathic pain intensity correlates only with sensory deficit and is not dependent on any other parameters. CPN consists of two forms with higher and lower intensity of pain symptoms. Symptomatic therapy is indicated in acute variant of PDN, but also in chronic cases accompanied with allodynia and hyperalgesia. ALA appears to be effective as an initial stage of management of moderate or mild CPN.

diabetic neuropathy, painful diabetic neuropathy, alpha-lipoic acid, pregabalin, duloxetine

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