Endocrine Abstracts

Objective: to study nerve functions in IDDM at an early stage to evaluate the prevalence of neuropathy.

Subjects and methods: The study included 20 children with IDDM and 10 healthy subjects as controls. Patients were subjected to clinical evaluation of neuropathic manifestations. Laboratory tests included fasting blood glucose and serum glycated hemoglobin (HbA1c). Electrophysiological study included motor conduction studies of the median and deep peroneal nerves and sensory conduction studies of the sural and median nerves. Autonomic function tests included cardiovascular reflex test as assessment of blood pressure response to standing up and to sustained hand grip and ECG tracing for the resting heart and heart rate variation during deep breathing and during standing, pupillary size and measurement of pupillary dark adaptation. Central nervous function by visual evoked potentials (VEPs).

Results: The study revealed the presence of neuropathic symptoms in only 2 patients (10%). Abnormalities in motor and sensory nerve functions were more common in lower than upper extremities and more in motor than sensory nerve functions. Age was positively correlated with nerve dysfunction while height was negatively correlated. Abnormal cardiovascular reflexes were common in heart rate response to standing which was abnormal in 90% of cases, and also smaller pupil/iris ratio and smaller pupil diameter. Although eyes of diabetic children showed no abnormalities in fundus examination, the implicit time of the P100 of the VEP, was significantly prolonged in eyes of IDDM cases with duration less than 5 years while the P100 amplitude was significantly reduced in IDDM patients with duration of diabetes more than10 years.

Conclusions: Subclinical peripheral neuropathy can be detected in diabetic children. Screening for peripheral and autonomic nerve function are justified in diabetic children. Eyes of IDDM patients show neural conduction delay in VEP implicit time before the appearance of any retinopathy.