Prediabetes does not cause small fiber neuropathy (P5.118)

Objective: To evaluate the association between glycemic status and small fiber neuropathy (SFN)

Background: The association between prediabetes (PD) and SFN is controversial.

Design/Methods: A cohort of patients with symptoms consistent with SFN, attending the neuromuscular clinic at the University of Nebraska Medical Center was reviewed. All patients had normal electrophysiologic studies and underwent tests to assess small nerve fibers. SFN was diagnosed based on at least 2 abnormal tests of QSART, QST or skin biopsy. PD is defined by fasting plasma glucose (FPG) of 100–125 mg/dL, 2-hour glucose of 140–199 mg/dL or HgA1C of 5.7–6.4%. Diabetes mellitus (DM) is defined by FPG ≥ 126 mg/dL, 2-hour glucose of ≥ 200 mg/dL or HgA1C ≥6.5%. Patients with other causes of SFN were excluded.

Results: 199 patients were reviewed. 82 patients were excluded due to the presence of other causes of SFN. Among 117 patients included, 10 had DM, 37 had PD, 54 had normoglycemia (NG) and 16 had unknown glycemic status. There was no difference between age, gender and duration of neuropathic symptoms between DM, PD and NG. There was no significant difference in intraepidermal fiber density (IENFD) at the ankle between PD and NG. The rate of skin biopsy abnormality and SFN was not higher in PD compared to NG. In contrast, ankle IENFD was lower in DM compared to PD or NG, and the rate of skin biopsy abnormality and SFN was higher in DM than in PD and NG. Linear regression analysis showed an association between HgA1C and IENFD if DM patients were included but not in PD and NG alone.

Conclusions: We found no evidence of a higher prevalence of SFN or abnormality of IENFD in PD relative to NG in patients presenting with distal sensory symptoms. PD does not appear alone to cause SFN.

Disclosure: Dr. Thaisetthawatkul has nothing to disclose. Dr. Fernandes has nothing to disclose. Dr. Herrmann has received personal compensation for activities with Medpace as Clinical Trial Adjudication.