Evaluation of visual pathways using visual evoked potentials in the subjects with impaired fasting glucose and impaired glucose tolerance

Pre-diabetic stage (impaired glucose tolerance and impaired fasting glucose) is an important clinical presentation defined as pre-diabetic period. Aim of the present study was to evaluate whether retinopathy developed in the patients with impaired fasting glucose and impaired glucose tolerance in the laboratory test without any symptom and whether injury occurs in the retinal ganglion cells using patterned visual evoked potentials. Thus, it was aimed to investigate whether alterations occurred in visual evoked potentials, if alterations occurred whether they could be used as predictor for development of retinopathy in the pre-diabetic patients and whether they could clarify mechanism of retinopathy. This prospective study was conducted on 60 patients presenting to Neurology and Endocrinology and Metabolic Diseases polyclinic of Hospital of Celal Bayar University with impaired fasting glucose and impaired glucose tolerance. In the present study, two groups of patients and one control group was created. In the groups of patients, the group of impaired fasting glucose (IFA) included 30 patients (21 women, 9 men) and the group of impaired glucose tolerance (IGT) included 30 patients (23 women, 7 men). The total pre-diabetic patient group included 60 patients (44 women, 16 men). To eliminate the age and gender factor the control group consisted of 44 women and 16 men. All groups gave detailed history and underwent physical and ophthalmological examination (visual acuity and funduscopic exam). Then, pre-diabetic patient group underwent examination with visual evoked potentials for detection of development of retinopathy. In the present study, we found increases in latency of P100 in visual evoked potentials in the patients with newly diagnosed IGT without any ophthalmological symptom. By the means of electrophysiological studies, we found that visual evoked potential might be used with predictive value in determining presence of retinopathy in the pre-diabetic stage