Aim Diabetes mellitus (DM) is a systemic disease with insufficient secretion of insulin or poor response to insulin. This typically causes poor control of blood glucose level leading to a range of complications. Early detection of the retinal function alteration in DM is needed.

Methods A newly modified paradigm—slow double-stimulation multifocal electroretinogram (mfERG)—was introduced to measure early changes of retinal function in DM and to investigate changes in the adaptation mechanisms in the diabetic retina. The mfERG was measured by using a slow double-stimulation mfERG paradigm (M¹M²OOO).

Results The m1 amplitude of M¹ stimulation from diabetic subjects was significantly reduced in ring 1 in contrast to that of a control group. The m2 amplitude of M² stimulation from diabetic subjects was also significantly reduced in ring 1 and 2 as compared with those of the control group. The m1/m2 ratio which minimises intersubject variation shows a reasonable differentiation between the control and diabetic groups. There was a significant increase in the amplitude ratio from diabetic subjects in ring 2 and 3 as compared with those of the control group.

Conclusions The present findings suggest that the new mfERG paradigm is a fast and sensitive test for the detection of early functional changes in the diabetic retina.