Can diabetes cause blurry vision? Yes, and there are two very different reasons. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says high blood sugar can change fluid levels or cause swelling in the tissues that help the eye focus, and that this kind of blur is temporary. Longer-term damage from diabetes, such as swelling in the retina or a cataract, can also blur vision, and that blur does not clear on its own.
Key takeaways
- NIDDK says blurry vision from high blood sugar is temporary and goes away when glucose gets closer to normal.
- Blur that stays can come from diabetic macular edema, cataracts, or retinopathy, which need an eye doctor.
- The American Academy of Ophthalmology (AAO) advises getting blood sugar stable before an eye exam so the glasses prescription is accurate.
- Flashes of light, many new floaters, a curtain-like shadow, or vision loss need an eye care professional right away.
- Only a dilated eye exam can tell the causes apart.
Blurry Vision and Diabetes: The Short Answer
- Blurry vision is a listed symptom of diabetes. The Centers for Disease Control and Prevention (CDC) includes it among symptoms that type 1 and type 2 diabetes can share.
- High blood sugar can blur focus for a while. NIDDK says this is temporary and fades as glucose moves closer to normal.
- Changing a treatment plan can blur vision too. NIDDK says some people have blurry vision for a few days or weeks when their diabetes care plan or medicines change.
- Severe low blood sugar can affect sight. CDC lists trouble seeing clearly among the symptoms of severe lows.
- Blur that lasts needs an exam. Diabetic eye disease can cause it, often with no pain.
Why High Blood Sugar Blurs Vision
The lens inside the eye changes shape to focus light. NIDDK explains that high glucose can change fluid levels or cause swelling in the tissues that help the eye focus, which leads to blurred vision. It adds that in the short term you are not likely to have vision loss from high blood glucose.
AAO describes the same pattern: if blood sugar is not under control, blurry vision can come and go, and it goes away when blood sugar is controlled. That has a practical effect on glasses. AAO advises getting blood sugar stabilized before an eye exam so you get the correct prescription. A prescription measured during a high-glucose stretch may not fit when your levels settle.
If your blur follows your readings, write down the time and the glucose number each time it happens. Our guide to checking your blood sugar at home explains the routine, and the pattern is useful information for your eye doctor.
Blurry Vision After a Change in Treatment
NIDDK says people sometimes have blurry vision for a few days or weeks when they change their diabetes care plan or medicines, and it describes this kind of blur as temporary.
There is a separate reason to tell your eye doctor about treatment changes. The American Diabetes Association's (ADA) Standards of Care in Diabetes—2026 say retinopathy status should be assessed when glucose-lowering therapies are intensified, because rapid reductions in A1C have been linked to an initial worsening of retinopathy. Do not stop or adjust a medicine on your own because of blurry vision. Tell your care team and your eye doctor what changed and when.
Low Blood Sugar and Vision
CDC says severe low blood sugar, below 54 mg/dL, can bring weakness, trouble walking or seeing clearly, confusion, and in some cases seizures. Treating a low follows the plan your care team gave you. Our guide to low blood sugar symptoms lists the earlier warning signs. If you cannot see clearly and a low is possible, follow your low-blood-sugar plan and get help if you cannot treat it yourself.
Blurry Vision That Does Not Go Away
Temporary glucose-related blur is only one cause. These are the others that matter most for people with diabetes.
| Possible cause | What it can look like | What it needs |
|---|---|---|
| Glucose-related lens swelling | Blur that comes and goes and fades as glucose nears normal (NIDDK, AAO) | Steadier glucose under your care plan; an exam if it persists |
| Diabetic macular edema | Blurry or wavy vision, objects that look different sizes in each eye, dull colors (NEI) | A dilated exam and treatment from an eye doctor |
| Cataract | Cloudy or blurry vision, faded colors, glare, halos, frequent glasses changes (NEI) | An exam; surgery is the only way to remove a cataract (NEI) |
| Diabetic retinopathy with bleeding | Dark floating spots or streaks, blurry vision, vision loss (NEI, CDC) | Prompt eye care |
| Glaucoma | Often no early symptoms; side vision fades first (NEI) | Regular dilated exams with eye pressure and side-vision tests |
The National Eye Institute (NEI) says diabetic macular edema happens when blood vessels in the retina leak fluid into the macula, the part needed for sharp, central vision, and that this causes blurry vision. Our guides explain what diabetic macular edema is, whether diabetes causes cataracts, and whether diabetes causes glaucoma. For retinopathy itself, see whether diabetic retinopathy is reversible.
Clues to Share With Your Eye Doctor
You cannot tell these causes apart by looking in a mirror. NIDDK notes that your eyes may seem fine, and that a full dilated eye exam is the only way to know for sure. What you can do is give your eye doctor useful clues:
- Does the blur come and go with your glucose readings, or is it there all the time?
- Is it in one eye or both?
- Do straight lines look wavy, or are there dark or empty areas?
- When did it start, and did a medicine or plan change around then?
- Are colors duller, or do lights seem too bright or have halos?
When Blurry Vision Is an Emergency
NIDDK says to call a doctor right away if you notice sudden changes in your vision, including flashes of light, many more floaters than usual, or a curtain-like shadow across your sight. These can be signs of a detached retina, which NIDDK calls a medical emergency. MedlinePlus adds vision loss and eye pain or redness to the list of reasons to call an eye care professional right away.
NEI also describes a type of glaucoma that can come on suddenly with intense eye pain, an upset stomach, a red eye, and blurry vision. NEI says to go to your doctor or an emergency room now if you have these symptoms.
Everyday Steps That Support Your Eyes
- Keep your dilated eye exams. ADA says adults with type 2 diabetes should have an initial dilated, comprehensive eye exam at diagnosis, then at least yearly if any retinopathy is present, and every 1 to 2 years may be considered if exams are normal and glucose is within goal. Our guide to how often diabetics should get an eye exam covers timing.
- Work on the ABCs. NIDDK lists A1C, blood pressure, and cholesterol as the key numbers, plus quitting smoking if you smoke. See what tests people with diabetes need each year.
- Plan for dilation. NIDDK says vision is blurry for a few hours after a dilated exam, so ask how you will get home.
- Report changes promptly. AAO says the sooner you notice a symptom, the more likely treatment will help.
For a wider view of how diabetes affects the eyes, see how diabetes affects the eyes.
Questions to Ask Your Care Team
- Could my recent blurry vision be related to a change in my glucose or my medicines?
- Should I see an eye doctor before getting a new glasses prescription?
- When is my next dilated eye exam, and should it be sooner?
- What readings should I record if my vision blurs again?
- Which symptoms should send me to urgent care?
Frequently Asked Questions
Can high blood sugar cause blurry vision?
Yes. NIDDK says high glucose can change fluid levels or cause swelling in the eye tissues that help you focus, which blurs vision. This type of blurry vision is temporary and goes away when your glucose gets closer to normal.
Can low blood sugar cause blurry vision?
It can. CDC lists trouble seeing clearly among the symptoms of severe low blood sugar, which is below 54 mg/dL. Treat a low using the plan your care team gave you, and get help if you cannot do it yourself.
How long does blurry vision from diabetes last?
NIDDK says people sometimes have blurry vision for a few days or weeks when they change their diabetes care plan or medicines, and that glucose-related blur goes away as glucose nears normal. Blur that stays or keeps returning should be checked by an eye doctor.
Should I get new glasses if my vision is blurry?
Ask first. AAO advises getting your blood sugar stabilized before an eye exam so you get the correct glasses prescription. An eye doctor can also check whether the blur has a cause that glasses will not fix.
Is blurry vision a sign of diabetes?
It can be. CDC lists blurry vision among the symptoms that both type 1 and type 2 diabetes can cause, along with frequent urination, increased thirst and hunger, and fatigue. Blurry vision has other causes too, so a blood test is the way to find out.
When is blurry vision an emergency?
Sudden changes need care right away. NIDDK lists flashes of light, many more floaters than usual, and a curtain-like shadow over your vision, which can signal a detached retina. NEI says intense eye pain with an upset stomach, a red eye, and blurry vision calls for an emergency room.
References
- National Institute of Diabetes and Digestive and Kidney Diseases. "Diabetic Eye Disease." Accessed October 2026.
- American Academy of Ophthalmology. "Surprising Facts About Diabetes and Your Eyes." Accessed October 2026.
- American Academy of Ophthalmology. "How Diabetes Affects Your Eye Care." Accessed October 2026.
- Centers for Disease Control and Prevention. "Diabetes Symptoms." Accessed October 2026.
- Centers for Disease Control and Prevention. "Low Blood Sugar (Hypoglycemia)." Accessed October 2026.
- National Eye Institute. "Macular Edema." Accessed October 2026.
- National Eye Institute. "Cataracts." Accessed October 2026.
- National Eye Institute. "Glaucoma." Accessed October 2026.
- National Eye Institute. "Diabetic Retinopathy." Accessed October 2026.
- MedlinePlus. "Diabetic Eye Problems." Accessed October 2026.
- American Diabetes Association Professional Practice Committee for Diabetes. "12. Retinopathy, Neuropathy, and Foot Care: Standards of Care in Diabetes—2026." Diabetes Care. 2026;49(Suppl. 1):S261–S276. Accessed October 2026.
Next Steps
Keep a short log of any blurry spells with the time, your glucose reading if you have one, and any medicine change. Bring it to your next eye exam and share it with your care team.
For adults with type 2 diabetes or prediabetes who want lifestyle education alongside clinical care, the Done With Diabetes™ program, a holistic approach to type 2 diabetes, organizes daily learning about meals, movement, sleep, and stress. It does not diagnose or treat eye conditions or diabetes, interpret test results, change medicines, or replace your care team or your eye doctor.