Insulin Use May Predict the Development of Diabetic Retinopathy

Jakob Grauslund, MD, PhD

Among people with type 2 diabetes (T2D) attending diabetic retinopathy (DR) screening in Denmark, markers including insulin use were important predictors for the development of present, incident, and progressive DR.

A multivariable model indicated that patients who used insulin were 2.3 times more likely to have DR and they had a 1.9–2.4 times higher risk for DR-development or progression, while the use of cholesterol-lowering medicine was associated with a lower presence of DR.

However, through the follow-up period in 2013 – 2018, the nationwide cohort reported a considerably lower prevalence, incidence, and progression of DR, when compared with earlier reports.

“Potential explanations for this might include that the recent years have led to better treatment and optimized risk factor control in diabetes, which might decrease the onset and progression of DR,” said Jakob Grauslund, MD, PhD, Department of Ophthalmology, Odense University Hospital.

Duration of diabetes was reported as a leading indicator of DR and proliferative DR (PDR), being 2.45 and 9.79 times more frequent in patients with a duration of more than 20 years than those who were diagnosed within 10 years.

The team of investigators evaluated the prevalence and incidence of DR along with associated markers in patients with type 2 diabetes in the Danish DR-screening program between 2013 and 2018. Stages of DR were defined according to the International Clinical Diabetic Retinopathy Disease Severity Scale as levels 0 (no DR), 1–3 (mild, moderate, and severe non-PDR), or 4 (PDR).

Investigators linked data from the national Danish Registry of Diabetic Retinopathy (DiaBase) to various national health registries in order to retrieve information on diabetes duration, marital status, comorbidity, insulin use, and systemic medication.

The study included all 153,238 people with T2D (56.4% male) from the study period, with a mean age of 66.9 years and duration of diabetes at 5.3 years.

The rates of use of insulin, non-insulin glucose lowering drugs, blood pressure lowering therapy and cholesterol lowering therapy at the first screening episode were reported as 15.8%, 86.5%, 77.8%, and 77.3%, respectively. Most patients did not have DR at their first screening (91.2%).

The prevalence and 5-year incidences of DR, 2-step-or-more progression of DR and progression to PDR were 8.6%, 2.8%, 0.7%, and 0.2%, respectively.

Multivariable regression models indicate the prevalence of DR was associated with male sex (odds ratio [OR], 1.30; 95% CI, 1.25 –1.36), age (OR, 0.77; 95% CI, 0.74 - 0.81 per 10 years of age), duration of diabetes (OR, 3.07; 95% CI, 2.96 –3.18 per 10 years), and the use of insulin (OR, 2.34; 95% CI, 2.24 - 2.44).

The prospective part of the study determined the leading marker of incident DR and progression to PDR were duration of diabetes (hazard ratio [HR], 1.98; 95% CI, 1.87 - 2.09; HR, 2.89, 95% CI, 2.34 - 3.58 per 10 years of duration) and use of insulin (HR, 1.88; 95% CI, 1.76 - 2.01; HR, 2.40, 95% CI, 1.84 - 3.13).

Meanwhile, the use of cholesterol-lowering medication was considered a protective marker (HR, 0.87; 95% CI, 0.81 – 0.93; HR, 0.70; 95% CI, 0.52 - 0.93).

The study, “Presence and development of diabetic retinopathy in 153,238 patients with type 2 diabetes in the Danish Registry of Diabetic Retinopathy,” was published in Acta Ophthalmologica.