Background/aim: There is evidence suggesting the occurrence of neurovisual abnormalities in patients with diabetes without retinopathy. However, the determination of abnormalities in the neural and glial elements in vivo is difficult. The aim of this study was to investigate whether a retinal nerve fibre layer (RNFL) defect (as determined by scanning laser polarimetry, SLP) is present in patients without clinical manifestations of diabetic retinopathy. Methods: 12 patients with type 1 diabetes mellitus (DM) without retinopathy or other diabetes induced microvascular complications, underwent a complete opthalmological examination, including automated perimetry and RNFL measurements with a nerve fibre layer analyser GDx. The data were compared with a normal control group matched for age and sex. Results: The superior segment retardation in patients with diabetes was lower than in the control group, based on the superior integral (0.19 (SD 0.06) v 0.23 (0.04) mm(2), (10.56) mum, p=0.007) parameters. Conclusion: This finding may be indicative of significant nerve fibre loss in the superior segment of the retina in patients with type 1 diabetes mellitus but without retinopathy. The meaning of intraretinal differences in RNFL retardation, indicating asymmetric NFL loss, in patients with diabetes is yet not understood.867725728