Xu and Li (1) inquire whether variables such as socioeconomic status (SES), sex, and smoking contribute to the higher proportion (20%) of adolescents with diabetic retinopathy (DR) within our cohort compared with that from the reported aggregated pediatric data (∼19% before 2010, ∼10.3% after 2010). As outlined in our original article (2), over the three decades we observed a significant increase in the prevalence of socioeconomic disadvantage (18.9% to 22.8%) and adolescents from an ethnic minority (9.2% to 27.9%). Despite these findings, SES and ethnicity did not reach statistical significance for DR or diabetic macular edema in multivariable generalized estimating equation analysis, in subgroup analysis by decade, or in youth with shorter diabetes duration (5–10 years). Although female sex was associated with DR in univariable analysis, sex did not reach statistical significance in the multivariable DR and diabetic macular edema models. Data on smoking were not collected. Nevertheless, both SES and ethnic minority status have been associated with suboptimal glycemic control and greater risk of DR (3). As such, these remain important variables for ongoing research and highlight the complex interplay between environmental influences and microvascular complications of type 1 diabetes (T1D).
Consistent with the conclusions in our manuscript, Xu and Li (1) identify the cohort’s older median age (16.9 years, interquartile range 15.4–18.1) and longer duration of diabetes (8.9 years, interquartile range 6.9–11.8), both well-recognized risk factors for DR. As such, many would have considerable postpubertal diabetes duration. Several studies examined the relationship between puberty and DR (3,4), citing concomitant hormonal fluctuations and suboptimal glycemic control as the mechanisms underpinning increased DR risk conferred by pubertal T1D onset. Our group has previously reported the positive association between puberty and DR in an incident cohort at 6 years’ duration (4). Nonetheless, DR was still present in 12% of prepubertal individuals (4,5). In our recent report we examined peripubertal T1D diagnosis as a categorical variable (onset age <5 years, 5–10 years, and >10 years of age), but this was not statistically significant in the multivariable model after inclusion of diabetes duration. Forced removal of duration demonstrated decreasing odds of DR with increasing age of T1D onset (5–10 years, odds ratio 0.58, 95% CI 0.48–0.69, P < 0.005; >10 years, odds ratio 0.29, 95% CI 0.23–0.38, P < 0.005 vs. age <5 years). Our study followed young people with T1D to 20 years of age, and, as such, those diagnosed at >10 years of age may have had a shorter duration of diabetes in which to develop DR. Subgroup analysis of adolescents aged 12–15 years demonstrated a similar trend in DR prevalence (32%, 14%, and 14% in consecutive time periods, P < 0.005), reinforcing the plateauing of DR prevalence reported in our original article.
This study of 2,404 individuals (5,487 observations) is derived from the largest registry cohort of adolescents with T1D in New South Wales, the most populous and ethnically diverse state in Australia. The higher prevalence of DR is likely explained by the older age and longer duration of diabetes, reflective of our study’s inclusion criteria.
See accompanying article, p. e184.
M.E.C. and K.C.D. are equal senior authors.
Article Information
Funding. M.E.C. is supported by a National Health and Medical Research Council Practitioner Fellowship (APP1136735).
Duality of Interest. No potential conflicts of interest relevant to this article were reported.
