Older age at onset of Type 1 diabetes significantly increases the risk for developing clinically significant macular edema (CSME), show study findings.
After 30 years with the metabolic condition, the estimated cumulative incidences of CSME were 17%, 27%, and 34% in study participants aged 0-4 years, 5-14 years, and 15-40 years at diabetes onset, respectively, report the researchers in Acta Ophthalmologica.
They add that the mean duration from onset of diabetes to CSME development was shortest in the oldest age group, at 17.6 years, compared with 23.6 years in the youngest group.
CSME "occurs primarily as a result of disruption of the blood-retina-barrier (BRB), which leads to intraretinal accumulation of fluid," explain Per-Henrik Groop (University of Helsinki, Finland) and colleagues.
"The older patients may have a reduced capability of producing a proliferative response [to hyperglycemia-induced cellular injury], and as a consequence, the older retina is more prone to BRB disruption and subsequent CSME as the predominant retinopathy phenotype," they add.
The findings emerge from analysis of 1354 participants of the FinnDiane Study (Finnish Diabetic Nephropathy Study) with Type 1 diabetes, defined as an onset up to the age of 40 years with C-peptide negativity and insulin treatment started within 1 year of diagnosis.
CSME was defined according to the Early Treatment Diabetic Retinopathy Study (ETDRS) classification protocol, and was observed in 18% of the study cohort, with 31% having proliferative retinopathy (PDR), and 73% of those with CSME also having PDR.
Onset of diabetes after 15 years of age was associated with a significant 3.72-fold increased risk for CSME compared with onset between 0 and 4 years. The risk for CSME was also a significant 1.89 times higher among patients in the 5 to 14-year age group compared with their younger counterparts.
Puberty had no significant effect on CSME incidence, note Groop et al, with a marginal and nonsignificantly higher rate of the eye condition among 6 to 11 year-olds compared with their 12 to 18 year-old peers, at 30% versus 24%.
The findings suggest that "age at onset of type 1 diabetes may modify the risk of CSME in type 1 diabetes patients by affecting the age at which patients become susceptible to microvascular complications," conclude the authors.
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