Impact of impaired glucose regulation on the functions of large and small fibers of peripheral nerves

Abstract

Background/aim: This article analyzes the incidence and characteristics of peripheral neuropathy in patients with impaired glucoseregulation (IGR).Materials and methods: A total of 120 IGR patients and 60 healthy controls were enrolled. All subjects underwent nerve conductionstudy (NCS) of large fibers and skin sympathetic response (SSR) and contact heat pain evoked potential (CHEP) testing of small fiberswith a Medtronic Keypoint machine (Medoc Ltd., Israel). IGR patients were evaluated using the Michigan Neuropathy ScreeningInstrument (MNSI).Results: The abnormal rates (MNSI >2) in IGR patients and NCS and SSR evaluations were 18.3%, 22.5%, and 39.2%, respectively. Allabnormal NCS findings were accompanied with abnormal SSR findings. Compared with the control group, the sensory nerve actionpotential wave of the posterior tibial and sural nerve was decreased in the IGR group (P = 0.01, P = 0.00), the SSR wave was reduced inthe upper and lower limbs (P = 0.002, P = 0.00), and the CHEP wave was decreased in opisthenar and shank (P = 0.00). Compared withthe control group, the CHEP wave was decreased in the shank in the normal SSR group (P < 0.05) and in the opisthenar and shank inthe normal NCS group (P < 0.05).Conclusion: : IGR patients have peripheral neuropathy characterized by impaired functions of large and small fibers focused on smallfiber and lower limb sensory nerves. CHEP can detect small fiber damage earlier than SSR and NCS.