Type 2 diabetes mellitus (T2DM) is negatively associated with peripapillary retinal nerve fiber layer (pRNFL) thickness, according to findings published in Diabetes. The study also found that patients with both T2DM and hypertension (HTN) had a thinner pRNFL than healthy individuals or those with T2DM alone.
This retrospective, cross-sectional study involved 325 eyes of 325 patients who were assessed for retinal abnormalities between 2017 and 2020. Researchers obtained measurements of the pRNFL via optical coherence tomography. All participants were assigned to 1 of 3 groups; T2DM (n=126), T2DM and HTN (n=56), and a healthy control group (n=143). Mean ages were 58±10.3, 64.8±7.8, and 59.3±9.0 years (P =.001); best corrected visual acuity was -0.002±0.061, 0.003±0.053, and -0.019±0.060 logMAR (P =.018); and men comprised 43.7%, 64.3%, and 42.0% of the groups, respectively. Glycated hemoglobin and diabetes duration did not differ significantly between the 2 T2DM cohorts.
Researchers observed significantly different pRNFL thicknesses (P =.005) between the groups. The control group had the thickest pRNFL (mean, 96.1±7.7 μm), followed by T2DM (mean, 94.4±8.6 μm), and lastly the T2DM-HTN group (mean, 91.6±9.6 μm). T2DM-HTN had thinner pRNFL than T2DM (P =.002) and T2DM had thinner pRNFL than the controls (P =.031).
No differences were observed in the superior and nasal regions when stratified by sector. However, the T2DM-HTN group had the thinnest layers, followed by T2DM and controls in the inferior (mean, 114.9 vs 123.9 vs 124.7 µm; P =.003) and temporal (mean, 67.4 vs 71.1 vs 72.7 μm; P =.026) sectors respectively.
Researchers also found that duration of diabetes negatively correlated with pRNFL thickness (R2, 0.125; P <.001) in the T2DM cohort.. The duration of both T2DM and HTN showed a negative correlation that was more strongly associated with HTN (R2, 0.121; P =.008) than T2DM (R2, 0.052; P =.092).
Hypertension (P =.005), diabetes duration (P =.011), age (P =.014), and glycated hemoglobin (P =.049) were significant predictors of pRNFL thickness in the univariate model, while HTN (β, -3.766; 95% CI, -6.535 to -0.997; P =.008) and diabetes duration (β, -0.236; 95% CI, -0.432 to -0.041; P =.018) were significant in the multivariate model.
Study limitations include its retrospective nature, possible selection bias, and confounding due to the failure to exclude HTN patients with a previous occurrence and subsequent regression of HTN retinopathy.
Lee M-W, Park G-S, Lim H-B, et al. Effect of systemic hypertension on peripapillary RNFL thickness in patients with diabetes without diabetic retinopathy. Diabetes. 2021;70(11):2663-2667. doi:10.2337/db21-0491