Role of inflammation in sensory neuropathy in prediabetes or diabetes.
OBJECTIVE
Prediabetes includes individuals with impaired glucose metabolism, and it has been associated with various complications of diabetes mellitus (DM), including peripheral neuropathy. We aimed to investigate the associations between pro-inflammatory (TNF-α) and anti-inflammatory (IL-10) cytokines and neuropathy of very distal sensory nerves in patients with prediabetes or type 2 DM.


METHODS
We included 50 patients with prediabetes, 50 patients with type 2 DM, and 44 controls in the study. Plasma levels of HbA1c, TNF-α, and IL-10 were analyzed. Electrodiagnostic testing was performed on dorsal sural and medial plantar sensory nerves, which are the very distal sensory nerves of the feet.


RESULTS
Abnormalities in nerve conduction studies (NCS) of the dorsal sural and medial plantar sensory nerves were substantially higher in patients with prediabetes or type 2 DM. In addition, plasma levels of TNF-α were significantly higher in patients with type 2 DM than in controls, whereas IL-10 levels were significantly lower in patients with both prediabetes and diabetes. However, we found no correlation between the levels of HbA1c, TNF-α, IL-10, and abnormalities in NCS of the dorsal sural or medial plantar sensory nerves in either patient group.


CONCLUSIONS
To our knowledge, this is the first study to assess the relationships between TNF-α, IL-10, and NCS of the most distal sensory nerves in patients with prediabetes or type 2 DM. The mechanisms involved in the pathogenesis of DM and diabetic peripheral neuropathy are complex. The pro-inflammatory stage and the high incidence of neuropathy in patients with prediabetes may suggest a possible causative effect; however, the potential role of inflammation in the pathogenesis of peripheral neuropathy needs further clarification.
Neurology, Tepecik Education and Research Hospital, Izmir, Turkey.
T
T
Duksal
Neurology, Tepecik Education and Research Hospital, Izmir, Turkey.
B I
BI
Tiftikcioglu
Neurology, Tepecik Education and Research Hospital, Izmir, Turkey.
S
S
Bilgin
Infectious Diseases and Clinical Microbiology, Tepecik Education and Research Hospital, Izmir, Turkey.
S
S
Kose
Neurology, Tepecik Education and Research Hospital, Izmir, Turkey.
Y
Y
Zorlu
D000328:Adult; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D003929:Diabetic Neuropathies / Q000097:blood*; D005260:Female; D006801:Humans; D016753:Interleukin-10 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D011236:Prediabetic State / Q000097:blood*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
C508609:IL10 protein, human; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10
Diabetes Mellitus; IL-10; TNF-alpha; dorsal sural nerve; inflammation; medial plantar sensory nerve; peripheral neuropathy; pre-diabetes