Patients with DME receiving anti-VEGF therapy should be provided continuous monitoring of renal function and blood sugar control to increase the likelihood of a good treatment response. Photo: Jay Haynie, OD. Click image to enlarge.

Intravitreal anti-VEGF injection is currently the mainstay treatment of diabetic macular edema (DME), which can cause severe visual impairment if left untreated. Since patients exhibit varying responses to anti-VEGF therapy, researchers recently investigated whether systemic factors may play a role. They identified two systemic factors correlating to the degree of treatment response, including low glomerular filtration rates and high glycated hemoglobin levels, suggesting that inadequate diabetes management or poor renal function may increase the likelihood of poor treatment response.

The study group retrospectively reviewed the medical records of 91 patients (112 eyes) who received anti-VEGF injections for macular edema secondary to NPDR. Patients were then divided into three groups based on injection response. The responsive group (77 eyes) consisted of participants who showed a reduction in edema of at least 20μm on OCT at any time over three, five and seven months. This group was further divided into complete (51 eyes) and incomplete (38 eyes) response groups based on the OCT findings at seven months. The third group, called the refractory group (14 eyes), included patients who did not show a reduction in central retinal thickness compared to baseline, indicating a lack of response to anti-VEGF treatment.

The analysis showed that the refractory group had significantly higher glycated hemoglobin levels and significantly lower estimated glomerular filtration rates than the responsive group. The multivariate logistic regression analysis found that both factors could predict the degree of response. Conversely, no systemic factors were significantly different between the incomplete and complete response groups.

“The effect of the injection treatment decreased as renal function—indicated by the presence of proteinuria, blood urea nitrogen, and creatinine—decreased,” the study authors explained in their paper, published recently in BMC Ophthalmology. “However, the glycated hemoglobin levels and only the glomerular filtration rate among renal functions showed significant differences between the responsive and refractory groups in multivariate regression analysis.” This finding, they suggested, indicates that “glucose control state has a more significant correlation with the treatment response of diabetic macular edema for intravitreal injection than the duration of diabetes.”

By forewarning DME patients that inadequate diabetes management or poor renal function may result in a poor response to treatment, this may potentially help increase patient compliance, especially considering the financial burden of continuous anti-VEGF injections, the study authors suggest. They advise, “Clinicians should explain to patients with diabetes the treatment prognosis and the need for continuous monitoring of renal function as well as blood sugar management.”