Venular Oxygen Saturation Is Increased In Young Patients With Type 1 Diabetes And Mild Nonproliferative Diabetic Retinopathy

Purpose To clarify how early in the development of diabetic retinopathy (DR) can oxygen (O-2) saturation changes be detected.Methods Retinal oximetry was performed in a cross-sectional study, involving 14- to 30-year-old individuals: 185 with type 1 diabetes (T1D) and 94 controls. The subjects were divided into four groups according to the grade of DR. One-way ANOVA and post hoc tests were used to test for differences in the mean O-2 saturations between the groups.Results Fifty-eight (31 %) of the T1D patients had nonproliferative DR. There was no significant difference in O-2 saturations between controls and T1D patients with no DR. Arteriolar and venular O-2 saturations in T1D patients were significantly higher in moderate/severe DR than in no DR (p = 0.009 and p > 0.001), while venular O-2 saturation was significantly higher in mild DR than in no DR (p = 0.013).Conclusion Increase in venular O-2 saturation could not be detected before mild retinopathy had developed, and the retinal O-2 saturation increase was measurable on the venular side first. Our results suggest that the increase in O-2 saturation is likely a consequence of DR.