Retinal capillary density in relation to diabetes duration and levels of glycaemia in young patients with type 1 diabetes

Purpose To examine retinal capillary plexus characteristics and their correlation with diabetes duration and levels of glycaemia in young type 1 diabetes (T1D) patients. Methods Cross‐sectional analysis of baseline data from an observational, prospective cohort study of 69 patients with T1D aged 6–32 (mean 16) years in T1D duration subgroups ≤ ½, 5, 10 or 15 years and 53 age‐matched healthy control subjects aged 8–34 (mean 17) years. Examinations included macular optical coherence tomography angiography (OCTA) and wide‐field fundus imaging. The primary outcome was capillary density of the superficial capillary plexus. Past HbA 1c values were collected retrospectively. Results Compared to healthy subjects, macular superficial capillary plexus density was 3.0% lower and the total area of non‐perfusion 0.18 mm 2 larger in T1D patients ( p = 5.92 × 10 −6 and p = 0.0033, respectively). Among patients with T1D duration longer than ½ year ( n = 52), multiple linear regression showed that higher past HbA 1c was significantly correlated with lower capillary density ( p = 0.016) as well as larger total area of non‐perfusion ( p = 4.4 × 10 −5 ) of the superficial capillary plexus, while diabetes duration was not ( p = 0.42 and 0.92, respectively), and age was for the latter outcome ( p = 0.29 and 0.037, respectively). Similar, but less prominent deficits were found for the deep capillary plexus. Conclusion This study suggests that the density of the superficial capillary plexus is lower in T1D of duration 5 years or longer, exacerbated by higher past HbA 1c values, supporting that tight glycaemic control promotes the maintenance of capillary perfusion.