Changes in retinal microvasculature and serum Gremlin-1 levels in acromegaly: A case-control study

•We enrolled 53 acromegaly patients in this cross-sectional study.•Retinal structure was examined by OCTA, as a novel, non-invasive tool for the comprehensive evaluation of retinal vasculature.•Gremlin-1 was found lower in the acromegaly group.•Although GH and IGF-1 are known as angiogenic factors, we found reductions in vascular densities in acromegalic patients.•It is known that abnormal glucose tolerance may result in reductions of vascular density, albeit our results revealed that the decrease in vascular densities was independent of glucose intolerance.•This study confirms the previous studies that demonstrated a reduction in retinal vascular densities in acromegaly; nevertheless, this is the first study combining Gremlin-1 with OCTA and also assessing the impact of glucose tolerance status on those changes. There are controversial results about the effects of GH/IGF-1 on retinal vasculature. Gremlin-1 has roles in both pituitary tumorigenesis and angiogenesis. Therefore, we aimed to detect retinal micro-vascular changes in acromegaly with OCTA and examine its association with serum Gremlin-1 levels. A cross-sectional, case-control study We included 53 acromegaly patients and age/gender-matched 31 healthy controls. To evaluate retinal structure, optical coherence tomography angiography (OCTA) imaging was performed. Gremlin -1 levels were measured by the ELISA method. Acromegaly patients had significantly lower superficial total density (p< 0.001), superficial parafoveal density (p = 0.002), superficial perifoveal density (p < 0.001); deep total density (p < 0.001), deep parafoveal density (p < 0.001), deep perifoveal density (p < 0.001). Total thickness and perifoveal thickness were significantly lower in the acromegaly group. Gremlin-1 levels were significantly lower in acromegaly patients (1.22(0.13) vs 1.38(0.29); p = 0.015, for acromegaly and control groups, respectively). We assessed study groups based on glucose tolerance status. Normal glucose tolerance (NGT) acromegaly patients had significantly lower superficial total density (p = 0.036), superficial perifoveal density (p = 0.003), deep total density (p = 0.023), and deep perifoveal density (p = 0.023) compared to NGT controls. According to backward linear regression analysis, the presence of acromegaly itself consistently showed a significant negative impact on all types of vascular density. Patients with acromegaly have decreased vascular density and lower levels of Gremlin-1 independent of