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October 31, 2026
Yes, in some people. When blood sugar falls quickly after a long stretch of high levels, diabetic retinopathy can get worse for a while. This is called early worsening. It was described decades ago with intensive insulin treatment. It has also been reported with semaglutide (Ozempic) in people who already had retinopathy [1,2].
Good long-term blood sugar control still protects the eyes. The answer is an eye exam and closer monitoring when treatment changes, not keeping blood sugar high or stopping medicine [1,3].
Do not stop or cut back insulin, Ozempic or any other diabetes medicine on your own because of this article. Talk with the clinician who prescribes it. This article is general education and does not replace care from your diabetes or eye team.
Key takeaways
In this article
Early worsening is often found on an exam before you notice it. But some symptoms mean bleeding or a detached retina and need fast care [4,5,6].
Call 911 if:
Go to an eye emergency service or ER now if you have:
Call your eye doctor the same day or next day if:
If you have retinopathy and have just started a new diabetes medicine, book an eye exam if none is scheduled. See our guide to urgent vision changes for more warning signs.
Early worsening of diabetic retinopathy is a usually short-term increase in retinal damage that can follow a rapid improvement in blood sugar. A review found it in 10% to 20% of people within 3 to 6 months of a sharp improvement. The rate was about twice as high in people with advanced retinopathy at the start [7].
Diabetic retinopathy is damage to the small blood vessels of the retina, the light-sensing layer at the back of the eye. It moves through stages, from mild changes to the proliferative stage, where fragile new vessels grow. Our guide to the four stages of diabetic retinopathy explains each one.
In people with little or no retinopathy, early worsening is often mild and short-lived. It mostly shows up as small cotton-wool spots and vessel changes on the exam. In people with advanced retinopathy, it can cause lasting damage [7].
A1C, also written HbA1c, is a blood test that shows your average blood sugar over the past 2 to 3 months [8].
No one knows exactly why. The cause is not well understood, and an older theory based on fluid shifts does not explain it well. One proposal is that insulin and VEGF, a growth signal made by oxygen-starved retina, may act together to drive abnormal vessel growth. This idea has not been proven [9].
What is clear is the pattern. The two strongest risk factors in the DCCT were a high A1C before treatment and a large A1C fall in the first 6 months [1]. Longer diabetes duration and more severe retinopathy at the start also raise the risk [7].
The Diabetes Control and Complications Trial (DCCT) studied people with type 1 diabetes. Early worsening in the first year affected 13.1% of people on intensive insulin, compared with 7.6% on standard treatment. About half had recovered by 18 months, and the long-term benefits of intensive treatment far outweighed this risk [1].
Over about 6.5 years, intensive treatment cut the risk of developing retinopathy by 76%. In people who already had mild retinopathy, it slowed progression by 54% [3].
No case of early worsening in the DCCT caused serious vision loss. Two people developed high-risk proliferative retinopathy and three developed clinically significant macular edema, and all responded well to treatment [1].
The DCCT authors found no evidence that lowering blood sugar more slowly reduced the risk [1]. A later review reached the same conclusion [7]. That is why the focus is on eye checks, not on slowing diabetes treatment.
Semaglutide has not been shown to cause retinopathy on its own. In the SUSTAIN-6 trial, eye complications were more common on semaglutide, mainly in people who already had retinopathy. A later analysis linked most of the difference to how fast and how far A1C fell in the first 16 weeks [2,10].
SUSTAIN-6 was a 2-year trial in 3,297 people with type 2 diabetes and high heart risk. Retinopathy complications, such as eye bleeding or needing laser or injections, occurred in 3.0% on semaglutide and 1.8% on placebo [2,11].
The extra risk was concentrated in people with retinopathy at the start: 8.2% on semaglutide versus 5.2% on placebo. In people without known retinopathy, rates were 0.7% versus 0.4% [2].
A follow-up analysis found the excess was mostly in people who had retinopathy, high A1C at the start and insulin use. Other SUSTAIN trials showed no imbalance in eye events [10]. This was a post hoc analysis, so it supports the early worsening explanation but cannot prove it.
The current US label lists diabetic retinopathy complications as a warning. It notes that rapid improvement in glucose control has been linked with temporary worsening of retinopathy, and that long-term effects have not been studied [2].
The label advises monitoring patients with a history of diabetic retinopathy. It tells patients to contact their doctor if their vision changes [2].
A 2025 study used health records from 14 databases and included 810,390 new semaglutide users with type 2 diabetes. It found no higher risk of proliferative retinopathy or treatment-needing retinopathy or macular edema with semaglutide, compared with other common diabetes medicines [12].
Observational studies like this can be affected by differences between groups and by how diagnoses are coded. The authors still advised close eye follow-up when starting new diabetes medicines [12]. FOCUS, a trial designed to measure semaglutide's effect on the retina over 5 years, was still running in October 2026 [13].
Tirzepatide (Mounjaro) is another strong glucose-lowering medicine. In a 2025 study, it was linked with more new proliferative retinopathy. This was mainly in people who already had moderate or worse retinopathy, or milder retinopathy with macular changes. In people with no retinopathy, it was linked with fewer new cases. Its label also advises monitoring for retinopathy [14,15].
In that study, new proliferative retinopathy occurred in 1.1% of people on tirzepatide and 0.5% of matched people not taking it [14]. The study was observational, so it cannot prove the drug caused these changes.
The Mounjaro label section on retinopathy was revised in August 2026. It says temporary worsening has been reported with rapid glucose improvement and that patients with a history of retinopathy should be monitored [15].
Across six large heart-outcome trials of GLP-1 medicines, the drug class as a whole was not linked with more retinopathy. But trials where A1C fell further showed more retinopathy events. The authors advised checking retinopathy status when intensifying glucose-lowering treatment [16].
Yes. Early worsening is linked to the size and speed of the blood sugar drop, not to one drug. It was described with intensive insulin. It has also been reported after automated insulin delivery systems and after bariatric (weight-loss) surgery. It can occur in early pregnancy when blood sugar is brought down quickly [1,7,17,18].
Insulin pumps and automated insulin delivery. A 2026 review looked at people with type 1 diabetes starting hybrid closed-loop systems. In studies that checked the retina within a year, early worsening rates ranged from 8.9% to 26.5%. The certainty of this evidence was very low, and better studies are needed [17].
Bariatric surgery. Early worsening has been described after weight-loss surgery [7]. A review of controlled studies found fewer new cases of retinopathy after surgery than with medical treatment alone. There was not enough data to judge whether existing retinopathy gets better or worse [19].
Pregnancy. In pregnant women with diabetes, a high starting A1C and a large early improvement were linked with more retinopathy progression [18]. Pregnancy needs its own eye plan.
The risk is highest in people who have had high blood sugar for years and already have retinopathy, especially moderate nonproliferative retinopathy or worse. A high A1C before treatment and a large fall in the first months add to the risk. People with no retinopathy and a modest A1C change have a much lower risk [1,7,10].
The table below compares lower-risk and higher-risk situations, using the DCCT and a 2018 review with screening advice. Your own eye doctor sets your actual schedule.
| Situation | Relative risk of early worsening | Eye checks discussed in the research |
|---|---|---|
| Short diabetes duration and no or minimal retinopathy | Lower | Exam before starting, then about every 6 months in the first year |
| Years of high blood sugar, or moderate nonproliferative retinopathy or worse | Higher | Exam before starting, then about every 3 months for 6 to 12 months |
| Severe nonproliferative or proliferative retinopathy | Highest | Prompt retinal treatment, such as laser, with timing planned by both teams |
Sources for the table: the DCCT authors suggested an exam before intensive treatment and every 3 months for 6 to 12 months in higher-risk people. The 2018 review suggested quarterly checks for a year in high-risk people and every 6 months in low-risk people [1,7].
Anyone with known retinopathy should have a dilated eye exam before, or soon after, starting a GLP-1 medicine, insulin, a pump or weight-loss surgery. So should anyone overdue for an exam or with years of high A1C. The exam sets a baseline and finds disease that needs treatment first [2,7,16].
An eye exam should not become a reason to put off diabetes treatment that your doctor says is urgent. Ask how soon the exam can happen.
In a few people with very advanced retinopathy, the eye and diabetes teams may plan the timing together. For example, they may arrange laser treatment promptly, sometimes before treatment is stepped up [1,7]. That is a decision for your doctors, not one to make on your own.
Our guide to how often you need a diabetic eye exam explains routine screening. If retinopathy needs treatment, see diabetic retinopathy injections, laser and surgery.
No, not on your own. The Ozempic and Mounjaro labels advise monitoring people with a history of retinopathy, and retinopathy is not listed as a reason to avoid Ozempic. Long-term high blood sugar harms the eyes, kidneys and nerves. In type 1 diabetes, missed insulin can cause diabetic ketoacidosis, an emergency. Plan any change with your prescriber [2,3,15,20].
Keeping blood sugar high to "protect" the eyes does not work. In the DCCT, intensively treated people who had early worsening still did as well as or better than standard-treatment people who did not [1].
If your eye doctor finds worsening, ask them to send a report to your diabetes team so the two teams can decide together.
No. A fast change in blood sugar can change how the lens focuses light. This can make vision blurry for days or weeks, then settle as glucose steadies. But you cannot tell focusing blur from retinal swelling or bleeding by yourself, so new blurred vision should be checked [4,21].
In one study of people starting intensive glucose control, every eye became temporarily farsighted. The change peaked at about 10 days and returned to normal within 2 to 12 weeks [21]. Ask your eye doctor whether to wait for vision to settle before updating your glasses.
Our article on how diabetes affects the retina, lens and vision explains these focusing changes.
Usually not, but it can. In the DCCT, no case caused serious vision loss and about half recovered within 18 months. In people who already have advanced retinopathy, early worsening can cause lasting damage. Laser, injections or surgery can treat sight-threatening changes when they are found in time [1,7].
Ask your eye doctor what has changed. A few extra spots, new macular swelling and new abnormal vessels need very different plans.
Our guide to preventing diabetic vision loss covers blood sugar, blood pressure and screening in more detail.
Netra Restoration Therapy (NRT) is an adjunctive program based on acupuncture and Oriental medicine principles. It is offered alongside care from your diabetes team and eye doctor, never instead of it. You can read what NRT involves on our site.
NRT has not been tested in controlled trials for early worsening of diabetic retinopathy. It does not replace diabetes medicines, eye exams, laser or injections, and it should never delay them. Tell your prescriber about any herbs or supplements you take. Our page on how NRT effectiveness is assessed explains how we discuss evidence.
Ozempic has not been shown to cause retinopathy on its own. In one large trial, eye complications were more common with semaglutide, mainly in people who already had retinopathy and whose A1C fell fast. A large 2025 real-world study found no higher risk than with other diabetes medicines.
Yes. Retinopathy is not listed as a reason to avoid Ozempic. The US label advises that people with a history of retinopathy be monitored for progression. Get a dilated eye exam before or soon after starting, and follow the visit schedule your eye doctor sets.
It can in some people. A large, fast fall in A1C after years of high blood sugar can cause early worsening of retinopathy, especially if retinopathy is already present. The long-term benefits of good control are still much greater, so the answer is eye monitoring, not keeping A1C high.
A 2025 study linked tirzepatide with more new proliferative retinopathy in people who already had retinopathy. It was linked with fewer new cases in people without retinopathy. The Mounjaro label advises monitoring anyone with a history of retinopathy.
Blur caused by focusing changes from shifting blood sugar usually settles within weeks. Blur from retinal swelling or bleeding may not settle and can need treatment. Because you cannot tell them apart yourself, have new blurred vision checked by an eye doctor.
Often it is not. In the DCCT, about half of people recovered within 18 months, and none had serious vision loss. In people with advanced retinopathy, it can cause lasting damage, which is why eye checks matter during the first months of new treatment.
If you have retinopathy, aim for a dilated eye exam before starting or soon after. Published advice for higher-risk people suggests checks about every 3 months for the first 6 to 12 months. Your eye doctor will set the exact schedule based on your findings.
Sources checked October 31, 2026.
This article provides general education and does not replace an individual eye examination, diagnosis or treatment plan. Sudden vision loss, a shower of new floaters, flashes or a curtain over your vision needs emergency eye care today, and you should never stop diabetes medicine without your prescriber.
