Incidence of Proliferative Diabetic Retinopathy at 5 years After T2D

How do factors such as insulin use and blood glucose control impact the overall risk of developing diabetic complications like retinopathy 5 years after type 2 diagnosis?

Diabetic retinopathy causes damage directly on the blood vessels of the light-sensitive tissues at the retina. This damage can lead to more severe glaucoma or even complete blindness; therefore, it’s essential to understand how diabetes can cause this complication and the incidence rate. However, few studies have been done to show the overall incidence of diabetic retinopathy in the diabetic population, or to highlight the incidence of diabetic retinopathy at five years, nine years, and ten years after a diabetes diagnosis.

The purpose of this study is to identify the incidence and risk factors for the development of proliferative diabetic retinopathy (PDR), tractional retinal detachment (TRD), and neovascular glaucoma (NVG) at five years post initial diagnosis of type 2 diabetes. Inclusion criteria included patients 18 years old or older with at least one inpatient claim with type 2 diabetes diagnosis, at least one prescription filled for diabetes medication, or two outpatient claims with a diagnosis of type 2 diabetes within 180 days. Exclusion criteria included gestational diabetes diagnosis or pregnancy one year prior or two months after the index date and patients diagnosed after October 1st, 2013, to allow a two-year follow-up. The total included patients in this study were 277,401. The information needed was taken from a commercial claims database. The incidence of PDR, TRD, and NVG was analyzed at two years and five years following diagnosis of type 2 diabetes. In addition, the associations between outcomes for PDR, TRD, NVG, and demographics, socioeconomic, and medical factors were tested.

The study showed that five years following the initial diagnosis of type 2 diabetes, 1.74% of patients developed proliferative diabetic retinopathy, 0.25% of patients had developed tractional retinal detachment, and 0.14% of patients developed neovascular glaucoma. Insulin use, maximum A1C >9%, renal disease, peripheral circulatory disorders, neurological disease, and older age at diagnosis were all risk factors for developing proliferative diabetic retinopathy. On the other hand, Medicare insurance, morbid obesity, and smoking were identified as protective factors in the development of proliferative diabetic retinopathy. In addition, insulin use was the risk factor with the highest incidence of developing PDR within five years of diagnosis. In contrast, older age at diagnosis had the lowest ratio of being a risk factor to cause proliferative diabetic retinopathy.

This study showed that 1.74% of patients develop proliferative diabetic retinopathy five years following a type 2 diabetes diagnosis. This subset of patients has a higher risk of complications that can follow this diagnosis; due to this increased risk in this population, it would be imperative to improve the screening schedules for this population of patients and early intervention strategies. The sooner the neovascular complications can be identified, the better the risk is for developing complications that can be more detrimental and severe. Further studies are needed as there are few that identify the risk five years after diagnosis of type 2 diabetes. In addition, studies showing proliferative diabetic retinopathy and other neovascular complications in type 1 diabetes patients are also needed as these complications can also be found in that patient population. This study, along with future studies, can lead to guideline changes in the screening time for specific patient populations and overall improvement in morbidity.

Practice Pearls:

• Proliferative diabetic retinopathy is a significant complication that can arise after diagnosis of type 2 diabetes; this can lead to more significant complications such as blindness if not addressed.
• At five years post initial diagnosis, the risk for developing proliferative diabetic retinopathy was greater with patients using insulin.
• Further studies should be done to continue the research on proliferative diabetic retinopathy, including in type 1 diabetes patients.

William S. Gange, Jennifer Lopez, Benjamin Y. Xu, Khristina Lung, Seth A. Seabury, Brian C. Toy Diabetes Care Sep 2021, dc210228; DOI:  10.2337/dc21-0228 Incidence of Proliferative Diabetic Retinopathy and Other Neovascular Sequelae at 5 years Following Diagnosis of Type 2 Diabetes

Diabetic retinopathy. American Optometric Association. https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/diabetic-retinopathy?sso=y. Accessed September. 5, 2021.

Erica Hicks, PharmD Candidate 2022, South College School of Pharmacy