Peripheral nerve conduction speed shows a disease control-dependent and -independent drop in type 1 diabetes mellitus in children

Background/Aim: Nerve conduction speed (NCS) abnormalities are considered to be early signs of diabetic peripheral neuropathy. We investigated which determinants impact the NCS and how it is related to markers of metabolic control in children and young adults with diabetes mellitus. Method: Fifty-four children aged five to 23 years suffering from type I diabetes mellitus were recruited into this study, which was conducted at the Children's Hospital of Eastern Switzerland in St Gallen from March 2016 to June 2022. The metabolic control parameters were recorded and a nerve conduction study analyzing three motor nerves and one sensory nerve was performed. The data were compared to a control population of healthy children of the same height, and the height-adjusted NCS (dNCS) was analysed. Results: For all four nerves under investigation, a statistically significant drop in the NCS of approximately 5 m/s independent of metabolic control was found, the peroneal nerve being the most sensitive. The NCS of the peroneal nerve correlated significantly negatively with the long-term haemoglobin with bound glucose (HbA1c) and highly significantly negatively with the standard deviation of mean glucose (SD), but there was only a trend with the HbA1c and the time in range (TIR) at the time of neurography. Interpretation: All patients with diabetes mellitus showed a reduced NCS, partly independent of metabolic control. This may be due to a lack of the C-peptide, which regulates critical axonal membrane enzymes. High glucose variability clearly increases the risk of neuropathy, together with but also independently of the mean plasma glucose level.