Effect of short-term hyperglycemia on multifocal electroretinogram in diabetic patients without retinopathy.

PURPOSE To investigate the effect of variations in blood glucose level on the multifocal electroretinogram (mfERG) in patients with type 1 diabetes without retinopathy. METHODS Fourteen patients were clamped sequentially and in random order at 5 and 15 mM blood glucose for 75 minutes on the same day. MfERG was recorded in one eye at each level of blood glucose level. RESULTS Compared to euglycemia (5 mM), hyperglycemia was associated with an overall decrease in the implicit times and an increase in the amplitudes of the multifocal ERG. The effect of hyperglycemia on implicit time reached statistical significance for the summed first positive (P1) and second negative component (N2) of the first-order kernel (P = 0.0020 and 0.0005, respectively) and all components of the second-order kernel (P = 0.014, 0.0037, and 0034, respectively). These changes in the mfERG demonstrated no significant variation in relation to retinal location or long-term blood glucose level. CONCLUSIONS Steady-state hyperglycemia induced shorter first- and second-order kernel implicit times in patients with type 1 diabetes without retinopathy. The effects of hyperglycemia were not significant with retinal location. These results support the hypothesis that hyperglycemia accelerates retinal metabolism.