To investigate the association between levels of diabetes mellitus (DM) control and rates of visual field and retinal nerve fiber layer (RNFL) loss over time in glaucoma.
Retrospective cohort study.
351 eyes of 222 patients with type 2 DM with concomitant primary open-angle glaucoma (POAG) or suspected of glaucoma extracted from the Duke Glaucoma Registry.
All patients had at least two reliable standard automated perimetry (SAP) tests, two spectral domain optical coherence tomography (SDOCT) tests and two glycated hemoglobin (HbA1c) measures over time with a minimum follow-up of 6 months. Values of HbA1c were summarized for each patient as mean, peak, and fluctuation across time. Multivariable linear mixed models were used to estimate the effect of HbA1c on rates of change in SAP mean deviation (MD) and OCT RNFL thickness loss over time while adjusting for various confounding factors.
Rates of change in MD and RNFL thickness over time.
Subjects had a mean baseline age of 62.5±10.2 years and follow-up time of 6.9±5 years. Subjects had an average of 4.8 SAP tests (range: 2 to 28), 3.6 SDOCT tests (range 2 to 10), and 8.3 HbA1c tests (range 2 to 21). Average HbA1c mean was 7.1±1.1% (range: 5.4 to 11.7), peak HbA1c over time was 8.1±2% (range: 5.5 to 15.6) and HbA1c fluctuation was 0.6±0.6% (range: 0 to 4.4). Mean rate of SAP MD change was -0.15±0.36 dB/year, ranging from -2.55 to 0.57 dB/year. Mean rate of RNFL change was -0.76±0.45 μm/year, ranging from -2.15 to 2.49. After adjustment for confounding factors, there was no statistically significant association between mean, peak, or fluctuation in HbA1c levels and neither rates of MD change over time (P= 0.994, P = 0.689, P = 0.920, respectively) nor RNFL loss over time (P = 0.805, P = 0.575, P = 0.770).
We were not able to find a significant association between diabetes control, as measured by levels of HbA1c, and rates of visual field or RNFL loss over time in individuals with glaucoma or suspected glaucoma.
Copyright © 2020. Published by Elsevier Inc.