Poor glycaemic control and higher blood pressure (BP) are associated with the presence of diabetic retinopathy (DR) in young individuals with type 1 diabetes (T1D), a study has shown.
Moreover, higher HbA1c correlates with thinner central subfield thickness (CST) and inner plexiform layer (IPL), hinting at a link with retinal neurodegeneration.
“Although this cohort represents a recent population, it predates the latest innovations (eg, automated insulin delivery) shaping diabetes management today,” the investigators said. “These findings support the potential importance of controlling modifiable systemic risk factors in diabetic eye disease in youth with T1D.”
A total of 1,359 youth participants with T1D (2,704 eyes) from a tertiary diabetes centre were included in this retrospective cross-sectional chart review study. The investigators reviewed the records of these individuals with clinic visits from 2005 through 2020 and collected spectral-domain (SD) macula scans in a subset of patients. An automated retinal layer segmentation was done for all retinal layers.
Participants (mean age 13.7 years, 49.6 percent female) had a mean T1D duration of 7.0 years, mean T1D age of onset of 7.7 years, and mean HbA1c of 8.4 percent. Of the eyes, 2,565 (94.9 percent) had no DR, 139 (5.1 percent) had DR, and nine (0.3 percent) had diabetic macular edema (DME). [Ophthalmology 2026;133:1232-1239]
The presence of DR was significantly associated with older age, longer T1D duration, earlier T1D onset, higher HbA1c, and elevated BP. These associations persisted in multivariable models that included age, sex, T1D duration, and HbA1c.
Furthermore, DME in nine eyes correlated with overweight or obesity. In 109 eyes (69 participants) with SD optical coherence tomography imaging and no DR, higher HbA1c significantly correlated with thinner CST, ganglion cell layer (GCL), and IPL. Elevated BMI also demonstrated a significant association with thicker retinal nerve fibre layer, GCL, and IPL.
“Although cases of DME were extremely rare, DME presence may be associated with increased BMI, suggesting that risk factors may differ between DR and DME,” the investigators said.
Glycaemic control
These findings suggest the importance of glycaemic control in preventing DR among young individuals, according to the investigators. In earlier studies, strict glycaemic control with intensive insulin therapy delivered protective benefits against vascular and neural complications of T1D. [Diabetes Care 2019;42:875-882; N Engl J Med 1993;329:977-986; Diabetes Care 1999;22:99-111]
Notably, the association seen between higher HbA1c and thinner CST and IPL in the current study suggests a possible link between poor glycaemic control and retinal structural changes indicating early neurodegeneration prior to DR onset.
“However, longitudinal studies are needed to determine whether neuroretinal thinning precedes DR development and to understand better the underlying mechanisms,” the investigators said. “One possible explanation is that chronic hyperglycaemia may contribute to inflammation, ischaemia, or both, which have been hypothesized to be associated with retinal neuronal loss.”
The present study was limited by its cross-sectional design. Thus, temporal relationships could not be established. The results should also be interpreted as associations and not as causal relationships, according to the investigators.
“However, these findings support associations between modifiable systemic risk factors and DR and suggest the need for further longitudinal studies to determine whether modification of systemic risk factors may influence the development or progression of diabetic eye disease in youth with T1D,” they added.