medwireNews: Factors including insulin use and ethnicity can help predict who will develop proliferative diabetic retinopathy (PDR) within 5 years after type 2 diabetes diagnosis, say researchers.
Brian Toy and colleagues, from the University of Southern California in Los Angeles, USA, identified 71,817 people with newly diagnosed type 2 diabetes recorded in a nationwide commercial claims database between 2007 and 2015.
Of these, 1.74% developed PDR within 5 years of that diagnosis, they report in Diabetes Care.
In all, 40.2% of the people who developed PDR were insulin users, compared with 13.4% of those who did not develop it, and insulin use was the strongest independent predictor of PDR in multivariable logistic regression, at an odds ratio of 3.59. It was also significantly associated with development of the end-stage retinopathy manifestations of tractional retinal detachment (TRD) and neovascular glaucoma (NVG).
In addition, having a baseline glycated hemoglobin level higher than 7.5% (58 mmol/mol) and concomitant renal, peripheral circulatory, or neurologic disease were significant predictors of early retinopathy.
The researchers say that the association of other microvascular comorbidities with retinopathy risk implies that people with early PDR development “may represent those individuals not only with worse control of disease but who also had a longer duration of undiagnosed type 2 diabetes.”
They add that younger age was protective against early PDR development, potentially indicating a prompt diagnosis and less time with uncontrolled blood glucose.
“The current study also highlighted racial health disparities in the incidence of PDR compared with prior studies, which were generally racially homogeneous,” say Toy and team.
They found that Hispanic study participants had the highest PDR rate of 2.1%, followed by Black people at 1.9%, White participants at 1.6%, and finally Asian people at just 1.4%.
However, the researchers stress: “Asians comprise a diverse ethnic group; therefore, further studies are warranted to investigate differences in development of [diabetic retinopathy] among subsets of the Asian population.”
Furthermore, Black or Hispanic versus White ethnicity was independently associated with developing NVG within 5 years of diagnosis, although the study authors stress that rates of end-stage retinopathy manifestations were very low, at one in 400 people for TRD and one in 700 for NVG.
Developing either of these complications so early after diagnosis “likely reflects many prior years of undiagnosed type 2 diabetes,” they say.
The team concludes that, together with previous research showing increased vulnerability to cardiovascular complications in ethnic minorities, their findings “suggest a need for earlier and more widespread screening for vision-threatening complications of pathologic neovascularization among Black and Hispanic patients.”
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