# Does Semaglutide Make Diabetic Retinopathy Worse? In One Trial, Yes | This GLP SUSTAIN 6 found more diabetic retinopathy complications on semaglutide than placebo | who the signal applies to, and why a post hoc mechanism does not dismiss it. Publisher: This GLP Editorial Team Canonical: https://thisglp.com/research/does-semaglutide-make-diabetic-retinopathy-worse Updated: 2026-10-26 Published: 2026-09-16 [← Research](https://thisglp.com/research) Safety # Does Semaglutide Make Diabetic Retinopathy Worse? In One Trial, Yes A randomized trial found more retinopathy complications on semaglutide than on placebo, and the effect concentrated almost entirely in people who already had retinopathy, had poor glycemic control at baseline, and were being treated with insulin. [This GLP Editorial Team](https://thisglp.com/about)September 20268 min readUpdated September 2026 Who the signal was concentrated in · already had retinopathy · poor glucose control · treated with insulin · All three, together, and a fast fall in HbA1c over sixteen weeks. **Research, not medical advice.** This GLP is independent and educational. Nothing here is a substitute for individualized care from a licensed clinician, and reading it creates no doctor–patient relationship. Talk to your own provider before starting, stopping, or changing any medication, peptide, or therapy. See our [methodology](https://thisglp.com/methodology) and [terms](https://thisglp.com/terms). ## Key takeaways - In a two-year cardiovascular outcomes trial, semaglutide was associated with a significant increase in diabetic retinopathy complications against placebo. - Across the other trials in the same program there was no imbalance in retinopathy adverse events. - A post hoc analysis attributed most of the effect to how fast and how far HbA1c fell in the first sixteen weeks, in patients who already had retinopathy, had poor control at baseline, and were on insulin. - Rapid improvement in glucose control is a recognized trigger for early worsening of retinopathy — it happens with insulin too. - None of this describes someone without diabetes, which is most people reading about these drugs. In one randomized trial it did, and the people it happened to are a narrow group. SUSTAIN 6 was a two-year cardiovascular outcomes trial in type 2 diabetes, and in it semaglutide was associated with a significant increase in diabetic retinopathy complications against placebo [\[1\]](https://thisglp.com/research/does-semaglutide-make-diabetic-retinopathy-worse#ref-1). A post hoc analysis attributed most of that to how fast and how far HbA1c fell in the first sixteen weeks, among patients who already had retinopathy, had poor control at baseline and were on insulin. Almost every safety question in this library ends with the evidence not supporting the worry, and this one does not. What follows is an attempt to say exactly who it applies to, because the answer is narrow and the alarm is broad. That gap is the one this site keeps finding between [what a trial established](https://thisglp.com/research/semaglutide-cochrane-review) and what gets repeated about it. Other diabetes complications need their own outcomes and comparators, including the [evidence on diabetic foot ulcers](https://thisglp.com/research/do-glp1-drugs-prevent-diabetic-foot-ulcers); a finding about the eyes does not settle a claim about the feet. ## What the trial found SUSTAIN 6 was a two-year pre-approval cardiovascular outcomes trial in type 2 diabetes, and in it semaglutide was associated with a significant increase in the risk of diabetic retinopathy complications compared with placebo. That is the finding, stated as the investigators state it, and it is the only randomized retinopathy signal in the program. Across the rest of the program — SUSTAIN 1 through 5 and the Japanese trials — there was no imbalance in retinopathy adverse events. The signal sat in one trial, which is both reassuring and the reason the trial mattered: it was the longest and it enrolled the sickest. The same is true of the kidney trial covered in [semaglutide and kidney disease](https://thisglp.com/research/semaglutide-and-kidney-disease), where the sickest population is also where the effect showed up. ## The mechanism, and what it does not do A post hoc mediation analysis used the initial change in HbA1c at week 16 as a covariate. Most of the effect could be attributed to the magnitude and rapidity of that reduction, and it concentrated in patients who already had retinopathy, had poor glycemic control at baseline, and were being treated with insulin. Early worsening of retinopathy after a fast improvement in glucose control is a known phenomenon and is documented with insulin. Guidance exists for it there, and the authors suggest similar guidance may be appropriate for semaglutide. A mechanism is not a dismissal It is tempting to read this as the finding being explained away. It is not. A post hoc analysis identifies a plausible route from the drug to the outcome; it does not remove the outcome, and it was not the trial’s prespecified question. What it does is tell a clinician where to look: at people whose retinas are already affected, whose control is poor, and whose glucose is about to improve quickly. That is a screening instruction, not a reassurance. ## The other eye signal, and why it is separate Retinopathy is not the optic nerve question. A separate pooling of eight cohorts put the relative effect for non-arteritic anterior ischemic optic neuropathy at 1.93 against no semaglutide, with a 95% confidence interval of 1.22 to 3.08 [\[2\]](https://thisglp.com/research/does-semaglutide-make-diabetic-retinopathy-worse#ref-2). In overweight or obese people specifically it came in at 1.68 (95% CI 0.72 to 3.91). Two different structures, two different literatures, and the second one is read here in [the optic nerve evidence by indication](https://thisglp.com/research/semaglutide-optic-nerve-by-indication). Neither excuses the other, and neither is evidence about the other. ## Whether it applies to you Every participant in these trials had type 2 diabetes. Most people buying these drugs from the sellers tracked here do not, and for them there is no HbA1c to fall rapidly and no pre-existing retinopathy for it to worsen. The finding does not transfer to that population, and nothing in this literature suggests it should. If you do have diabetes and any degree of retinopathy, this is a conversation to have before starting rather than after — with someone who can look at your retinas. That is the part this market is worst equipped for. Most sellers publish nothing about who reviews a case or how to reach them, which we count in [what sellers will not tell you](https://thisglp.com/research/what-glp1-sellers-do-not-publish) and list in [the questions they leave open](https://thisglp.com/tools/questions-they-leave-open). A condition that needs monitoring is a poor fit for a service that does not describe any. ## Frequently asked Does semaglutide damage the eyes? In one two-year trial in type 2 diabetes it was associated with a significant increase in retinopathy complications against placebo. Across the other trials in the same program there was no imbalance. What explains it? A post hoc analysis attributed most of the effect to how fast and how far HbA1c fell in the first sixteen weeks, among patients who already had retinopathy, had poor control, and were on insulin. Does it apply without diabetes? Nothing in this literature suggests it does. Every participant had type 2 diabetes, and the proposed mechanism requires an HbA1c that falls rapidly from a poor starting point. What should someone with retinopathy do? Raise it before starting, with a clinician who can examine the retinas — and note that rapid improvement in glucose control triggers the same early worsening with insulin. ## Sources 1. \[1\] Vilsbøll T, et al. (2018). Semaglutide, reduction in glycated haemoglobin and the risk of diabetic retinopathy Diabetes, Obesity and Metabolism. [PMID 29178519](https://pubmed.ncbi.nlm.nih.gov/29178519/) 2. \[2\] Khani E, et al. (2026). Semaglutide-Induced Nonarteritic Anterior Ischemic Optic Neuropathy: A Systematic Review and Meta-Analysis The Journal of Clinical Pharmacology. [PMID 42612051](https://pubmed.ncbi.nlm.nih.gov/42612051/) ## More in Safety - [ Medication list · Check combinations · Fluid loss · Changes kidney risk · Pharmacist · Choose a safe option ### Can You Take Ibuprofen With Ozempic? 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