Visual Evoked Responses in Type I and Type II Diabetes

Diabetes mellitus is a heterogenous group of metabolic disorders characterized by chronic hyperglycemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion, insulin action or both.

This is a combined cross sectional and case control study. This study was carried out in the Research laboratory of the department of physiology, Coimbatore medical college, Coimbatore. The approval of the ethical committee was obtained prior to the commencement of the study. A total of 80 subjects were included in the study of which 40 were diabetic patients, both type 1 and type 2 and 40 were control groups. They were of 30–70 years of age group. Group I includes 40 controls of age and sex matched healthy individuals. Group II includes 40 diabetic patients. Group II _A includes 20 type I diabetic patients. Group II _B includes 20 type 2 diabetic patients.. Neuroperfect EMG 2000 system and Autoanalyser are the materials used for the study. Pattern-shift visual evoked potential test was performed in a specially equipped electrodiagnostic procedure room.

One way ANOVA & Student ‘t’ test were used to assess the statistical significance. The mean value of the P₁₀₀ latency was significantly delayed in Group II _A and Group II _B patients as compared to that in Group I subjects.

The delay in P₁₀₀ latency was observed in diabetic patients before the development of overt retinopathty.