Poor Glycemic Control and Higher Blood Pressure Track With Early Diabetic Retinal Disease in Youth With Type 1 Diabetes

Poor Glycemic Control and Higher Blood Pressure Track With Early Diabetic Retinal Disease in Youth With Type 1 Diabetes

Highlights

In a cohort of 1359 youth with type 1 diabetes, diabetic retinopathy was uncommon but not rare, affecting 5.1% of eyes, while diabetic macular edema was very rare at 0.3% of eyes.

Older age, longer diabetes duration, earlier diabetes onset, higher HbA1c, and elevated or high blood pressure were associated with diabetic retinopathy, with glycemic control and blood pressure standing out as clinically modifiable factors.

Among youth without visible diabetic retinopathy who underwent OCT, higher HbA1c was associated with thinner central subfield thickness, ganglion cell layer, and inner plexiform layer, with the associations for central subfield thickness and inner plexiform layer remaining significant after multiple-comparison correction.

Overweight or obese BMI was linked to diabetic macular edema in the very small number of affected eyes and was also associated with thicker inner retinal layers on OCT, a finding that is biologically interesting but requires cautious interpretation.

Background

Diabetic retinopathy remains one of the most important microvascular complications of type 1 diabetes. In adults, decades of evidence have established chronic hyperglycemia as the dominant driver of retinopathy progression, with blood pressure and disease duration also contributing materially to risk. In children and adolescents, however, the epidemiology and phenotype of diabetic eye disease are somewhat different. Vision-threatening retinopathy is less common early in life, yet retinal injury may begin years before symptoms or clinically obvious lesions appear.

This possibility has sharpened interest in retinal neurodegeneration in diabetes. The retina is not only a vascular tissue but also a highly organized neural structure. Optical coherence tomography, particularly spectral-domain OCT, can quantify thickness of individual retinal layers and may detect subtle neural injury before classic microaneurysms, hemorrhages, or exudates are visible on examination. If systemic risk factors such as hyperglycemia or excess adiposity correlate with retinal neural thinning in youth, then pediatric diabetic eye care may need to move beyond lesion counting alone and consider the retina as an early target organ of broader metabolic injury.

The present study by Sampani and colleagues addresses this gap by examining modifiable risk factors associated with diabetic retinopathy, diabetic macular edema, and retinal neural layer thickness in a large cohort of young people with type 1 diabetes receiving care at a tertiary diabetes center. The study is clinically relevant because it asks not simply who has retinopathy, but whether potentially actionable systemic factors are already reflected in retinal structure during youth.

Study Design

Overall design and population

This was a retrospective cross-sectional chart review of youth younger than 22 years with type 1 diabetes who attended a tertiary diabetes center between 2005 and 2020. The investigators included 1359 participants, representing 2704 eyes. The cohort was nearly evenly split by sex, with 49.6% female. Mean age was 13.7 ± 4.3 years, mean diabetes duration was 7.0 ± 5.2 years, mean age at diabetes onset was 7.7 ± 4.7 years, and mean HbA1c was 8.4 ± 1.3%.

Ocular outcomes

The main outcomes were the presence of diabetic retinopathy, the presence of diabetic macular edema, and retinal layer thickness on spectral-domain OCT in a subset of participants. For OCT analysis, automated retinal layer segmentation was used to quantify all retinal layers. This allowed the authors to evaluate central subfield thickness and specific inner retinal layers, including the retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer.

Exposure variables

The study focused on clinically relevant risk factors, especially those that are modifiable. Variables examined included age, sex, diabetes duration, age at diabetes onset, HbA1c, blood pressure status, and BMI category. Because the study was cross-sectional, the reported associations reflect correlation at the time of assessment rather than temporal causation.

Statistical framework

Associations with diabetic retinopathy were examined in both univariable and multivariable models. Importantly, the multivariable models included age, sex, diabetes duration, and HbA1c, which helps separate the independent signal of glycemia from the strong background effects of age and longer exposure to diabetes. For OCT layer analyses, the authors also accounted for multiple comparisons, a methodologically important step given the large number of retinal thickness parameters evaluated.

Key Findings

Prevalence of diabetic retinopathy and diabetic macular edema

Most eyes had no diabetic retinopathy: 2565 of 2704 eyes, or 94.9%. Diabetic retinopathy was present in 139 eyes, corresponding to 5.1%. Diabetic macular edema was detected in only 9 eyes, or 0.3%. These figures support the broad view that severe diabetic eye disease is uncommon in contemporary pediatric type 1 diabetes populations, but they also show that measurable retinal complications are already present in a meaningful minority.

From a clinical standpoint, the prevalence data are useful for counseling families. The absolute risk of overt retinopathy in youth remains lower than in adults with longer disease duration, but the condition is clearly not absent. This matters because pediatric diabetes care has progressively improved over time, yet not all patients achieve optimal glycemic targets, and cardiovascular risk factors such as elevated blood pressure remain underrecognized in adolescents.

Risk factors associated with diabetic retinopathy

Several factors were significantly associated with diabetic retinopathy on initial analysis: older age, longer type 1 diabetes duration, earlier age of diabetes onset, higher HbA1c, and elevated or high blood pressure. These findings are biologically coherent. Longer duration increases cumulative glycemic and metabolic exposure; higher HbA1c reflects worse chronic glycemia; and hypertension can amplify retinal capillary injury through hemodynamic stress and endothelial dysfunction.

Notably, the associations remained significant in multivariable models that included age, sex, diabetes duration, and HbA1c. Although the abstract does not provide effect sizes, confidence intervals, or model coefficients, the persistence of HbA1c and blood pressure associations after adjustment suggests that these are not merely markers of older age or longer disease duration. Instead, they behave as independent and modifiable correlates of retinal disease burden.

The finding that earlier diabetes onset was associated with diabetic retinopathy deserves attention. Earlier onset may translate into longer lifetime exposure and possibly a more prolonged period of vulnerability during retinal development. It may also capture a phenotype of disease severity or reflect challenges in maintaining tight glycemic control across childhood. However, because age, duration, and age at onset are mathematically interrelated, this variable should be interpreted cautiously unless full model details are available.

Diabetic macular edema: rare but potentially linked to adiposity

Only 9 eyes had diabetic macular edema, making any inference tentative. Within that constraint, diabetic macular edema was associated with overweight or obese BMI. This is plausible, as obesity can be accompanied by insulin resistance, inflammatory signaling, dyslipidemia, and altered vascular permeability, all of which may contribute to retinal edema. However, the extremely small number of events sharply limits statistical precision. This result is best viewed as hypothesis-generating rather than practice-changing.

OCT evidence of possible early retinal neurodegeneration

The OCT subset included 109 eyes from 69 youth without diabetic retinopathy. This is an important design choice because it isolates structural retinal differences in eyes lacking clinically visible vascular lesions. In this subgroup, higher HbA1c was significantly associated with thinner central subfield thickness, ganglion cell layer, and inner plexiform layer. After correction for multiple comparisons, the associations with thinner central subfield thickness and thinner inner plexiform layer remained significant.

This pattern is notable because the ganglion cell layer and inner plexiform layer are central components of the inner retina, where neuroglial dysfunction has been implicated in early diabetic retinal injury. Thinning of these layers may signal neuroaxonal loss or altered retinal development associated with chronic hyperglycemia. The persistence of the inner plexiform layer association after statistical correction strengthens the argument that glycemia is related not only to visible microvascular disease but also to subclinical neural retinal change.

By contrast, overweight or obese BMI was associated with thicker retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer. This finding points in a different direction from the HbA1c-related thinning and may indicate low-grade inflammatory swelling, altered tissue hydration, segmentation effects, or developmental differences rather than true neuroprotection. Because the sample was modest and cross-sectional, the meaning of greater thickness is uncertain. In retinal disease, thicker is not always healthier; edema, gliosis, or inflammatory change can increase thickness before later atrophy occurs.

Clinical Interpretation

Why the HbA1c signal matters

The central clinical message is that glycemic control continues to matter deeply for the retina even in youth. This is entirely consistent with landmark evidence from the Diabetes Control and Complications Trial, which demonstrated that intensive glycemic control reduces the development and progression of diabetic retinopathy in type 1 diabetes. What this new study adds is a pediatric structural dimension: worse glycemia may already be reflected in thinning of inner retinal architecture before retinopathy is visible on standard examination.

For clinicians, this reinforces the concept that suboptimal HbA1c is not a benign pediatric phase that can simply be corrected later. The retina may already be changing. Whether these OCT changes are reversible, stable, or predictive of future retinopathy is not yet known, but their presence supports earlier, sustained efforts to improve time in range, reduce glycemic variability, and maintain HbA1c as close to recommended targets as safely possible.

Blood pressure deserves more attention in pediatric diabetes eye risk

The association between elevated or high blood pressure and diabetic retinopathy is especially actionable. Blood pressure can be overlooked in adolescents, where modest elevations may be dismissed as transient or situational. Yet pediatric diabetes guidelines already emphasize routine blood pressure assessment because hypertension contributes to both microvascular and macrovascular complications. This study strengthens the ophthalmic rationale for that recommendation. In practical terms, abnormal blood pressure readings in youth with type 1 diabetes should prompt confirmation, lifestyle counseling, and, when indicated, guideline-based treatment rather than passive observation.

How OCT findings may influence future screening paradigms

The OCT results are intriguing but not yet ready for routine risk stratification in all youth with type 1 diabetes. The imaging subset was small, and there are no longitudinal data showing that thinner central subfield thickness or inner plexiform layer predicts later retinopathy or visual outcomes. Still, these data fit with a growing body of work suggesting that diabetic retinal disease is a neurovascular disorder rather than a purely vascular one. If future longitudinal studies confirm that OCT-based inner retinal changes precede and predict clinically meaningful disease, pediatric diabetic eye screening could evolve to include structural biomarkers alongside traditional ophthalmoscopy or fundus photography.

Strengths and Limitations

Strengths

This study has several notable strengths. First, the cohort is large for a pediatric type 1 diabetes retinal study, with 1359 participants and 2704 eyes. Second, the investigators examined clinically relevant and modifiable systemic factors, making the findings directly useful for patient management. Third, the OCT analysis went beyond total retinal thickness to segment individual layers, which improves biological specificity. Fourth, the authors corrected the OCT analyses for multiple comparisons, reducing the chance of false-positive findings in a data-rich setting.

Limitations

The limitations are equally important. The retrospective cross-sectional design precludes causal inference. One cannot conclude that higher HbA1c caused retinal thinning or that elevated blood pressure caused retinopathy, only that these variables were associated at the time assessed. The abstract does not provide effect sizes, odds ratios, or confidence intervals, which limits quantitative interpretation. Diabetic macular edema occurred in only 9 eyes, making that analysis underpowered and unstable. OCT data were available in only 109 eyes from 69 youth, raising concerns about selection bias and limited generalizability. In addition, the cohort spans 2005 to 2020 and therefore predates widespread adoption of current diabetes technologies, including continuous glucose monitoring integration and automated insulin delivery, both of which have changed glycemic management substantially.

Another important limitation is residual confounding. Variables such as time in range, glycemic variability, lipid profile, socioeconomic factors, race and ethnicity, pubertal status, renal disease markers, and medication use are not reported in the abstract. Any of these could influence retinal outcomes. Finally, automated segmentation in young eyes is generally robust but is still subject to image quality and algorithmic limitations.

Implications for Practice and Policy

For pediatric endocrinologists, ophthalmologists, and primary care clinicians, the practice implications are straightforward. First, retinal risk reduction in youth with type 1 diabetes should continue to center on glycemic optimization. Second, blood pressure monitoring should be treated as a core component of diabetic eye risk management, not merely cardiovascular surveillance. Third, overweight and obesity may warrant additional attention, especially as pediatric type 1 diabetes increasingly coexists with excess adiposity.

For health systems and policy experts, the study underscores the value of integrated diabetes care models in which endocrinology, ophthalmology, nursing, diabetes education, nutrition, and social support operate in concert. The major risk factors linked to retinal disease here are modifiable, but modification requires infrastructure: access to diabetes technology, regular follow-up, blood pressure surveillance, nutrition counseling, and timely eye screening.

Conclusion

This study offers a clinically meaningful update on diabetic eye disease in youth with type 1 diabetes. Diabetic retinopathy was present in 5.1% of eyes and was independently associated with higher HbA1c and elevated or high blood pressure, reaffirming the importance of metabolic and hemodynamic control even early in life. Diabetic macular edema was extremely rare, though its possible association with higher BMI warrants further study. Perhaps most interestingly, among youth without visible retinopathy, higher HbA1c correlated with thinner central subfield thickness and inner plexiform layer on OCT, raising the possibility that retinal neurodegeneration begins before classic vascular lesions emerge.

The study does not change screening guidelines on its own, but it strengthens a message clinicians can already act on now: tighter glycemic management and careful blood pressure control are likely among the most important modifiable strategies for protecting the retina in young people with type 1 diabetes. The next step is longitudinal research in contemporary cohorts using continuous glucose monitoring and automated insulin delivery metrics to determine whether early OCT changes predict future retinal disease and whether they can be prevented or reversed.

Funding and ClinicalTrials.gov

The abstract provided does not report a ClinicalTrials.gov registration number. Specific funding details are not available in the supplied summary and should be confirmed from the full published article.

References

1. Sampani K, Ashraf M, Jacoba CM, Tirukovela S, Keady J, Silva PS, Laffel LM, Aiello LP, Sun JK. Modifiable factors associated with Diabetic Retinal Disease and Retinal Neural Layer Thickness in Youth with Type 1 Diabetes. Ophthalmology. 2026-05-19. PMID: 42162762.

2. Diabetes Control and Complications Trial Research Group. The effect of intensive diabetes treatment on the development and progression of long-term complications in adolescents with insulin-dependent diabetes mellitus: Diabetes Control and Complications Trial. J Pediatr. 1994;125(2):177-188.

3. Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Research Group, Nathan DM, Genuth S, Lachin J, et al. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med. 1993;329(14):977-986.

4. Donaghue KC, Marcovecchio ML, Wadwa RP, et al. ISPAD Clinical Practice Consensus Guidelines 2022: Microvascular and macrovascular complications in children and adolescents with diabetes. Pediatr Diabetes. 2022;23(8):1451-1480.

5. Cheung N, Mitchell P, Wong TY. Diabetic retinopathy. Lancet. 2010;376(9735):124-136.

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