Baseline Glycosylated Hemoglobin Did Not Affect Intravitreal Dexamethasone Implants

Patients who have diabetic macular edema (DME) can be effectively treated with intravitreal dexamethasone (DEX) implants without outcomes being affected by baseline glycosylated hemoglobin (HbA1c). According to Scientific Reports, this also extends to a year after baseline, where no major effects were found.

Patients who were diagnosed with diabetes could end up experiencing visual impairment due to DME, which is caused when there’s a vascular leakage and an accumulation of fluid in the macula. Patients who do not respond to anti-vascular endothelial growth factor have had success with DEX implants. The risk of DME is increased due to elevated HbA1c, but it is unknown if HbA1c also affects treatment effectiveness. This study was aimed at evaluating the relationship between baseline HbA1c and outcomes of patients who were treated with intravitreal DEX implants for DME.

Close-up of eye | Image credit: Firefighter Montreal - stock.adobe.com

All participants included were those who had intravitreal DEX implant injections between January 2013 and December 2020 for DME at the Seoul National University Hospital in Korea. All medical records for these patients were reviewed retrospectively. Patients were included if they had DME treated with a DEX implant, had measurements of HbA1c at the time of the DEX implant and at a 1-year follow-up, and had a follow-up that was longer than 1 year. Patients were excluded if they had a pre-existing macular pathology, had previous treatment within 3 months of their implant, had a history of ocular trauma, had significant media opacity, had prior intraocular surgery, or had advanced glaucoma.

Ophthalmologic examinations were performed on all patients. Baseline and 1-year follow-up measurements of HbA1c were taken from all patients. Patients who had a HbA1c of 7.0% or less had controlled diabetes and patients with HbA1c of more than 7.0% had uncontrolled diabetes. Patients were separated into 3 groups based on the changes in HbA1c levels after 12 months where their changes improved with more than a 0.5% decrease in HbA1c, remained stable, or had worsened through an increase of more than 0.5% in HbA1c after 12 months.

There were 90 patients and 90 eyes included in this study. A total of 45.6% had a baseline HbA1c of 7% or less, with the mean (SD) baseline HbA1c being 6.33% (0.48%) in these patients. In the 54.4% of patients who had HbA1c of more than 7%, the mean baseline HbA1c was 7.87% (0.78%). Patients who had an HbA1c measurement of more than 7% were more likely to be older with a mean age of 67.22 (7.53) years, were more likely to be women (57.1%), and had a longer mean diabetes duration (21.27 [9.02] years).

There was a mean central subfield thickness (CST) reduction of –147.22 (113.79) μm after 2 months in patients who had a baseline HbA1c of 7% or less and –130.41 (124.50) μm reduction in patients who had a baseline HbA1c of more than 7%. This difference between the 2 groups was not significantly different. The mean reduction for CST was not significantly different between the 2 groups. Patients with a baseline HbA1c of 7% or less had a mean time to retreatment of 4.32 (4.56) months compared with 6.04 (3.82) months in patients with a baseline HbA1c of more than 7%, though this was not significantly different.

Improved, stable, and worsened groups made up 30.0%, 46.7%, and 23.3% of the 90 eyes included in the study, respectively. Patients in the “improved” group had a mean baseline HbA1c of 7.91% (1.08%) compared with 6.85% (0.73%) in the stable group and 6.83% (0.95%) in the worsened group. The patients who were in the “improved” group also had a longer duration of diabetes (20.07 [9.17] years) compared with the stable (17.74 [9.44] years) and worsened (13.14 [6.78] years).

The mean CST reduction was –185.04 (157.59) μm from baseline after 2 months in the “improved” group, which was greater than the “stable” group (–123.52 [101.88] μm) and “worsened” group (–106.76 [73.47]). Through the remainder of the 12 months, there was no significant difference in the CST reduction, best corrected visual acuity, or the time to retreatment.

There were some limitations to this study. The retrospective nature could have caused selection bias. Small sample size and a shorter follow-up could have also contributed to this bias. Propensity score matching was not able to be performed due to the small sample size. Other factors that contribute to DME, such as blood pressure, cholesterol, and obesity, could not be controlled during this study.

The researchers concluded that any benefit from DEX was not associated with the baseline HbA1c or a change in HbA1c in the patient. This should indicate that DEX can be administered at any point, regardless of blood glucose control.

Reference

Lee HJ, Bae K, Yoon CK, Park UC, Park KH, Lee EK. The effect of glycosylated hemoglobin levels on the response to intravitreal dexamethasone implant for treating diabetic macular edema. Sci Rep. 2024;14:4690. doi:10.1038/s41598-024-55078-6