Does hypoglycaemia cause blurred vision?

The brain and eyes need a steady supply of glucose. When blood sugar falls too low, the visual system may not work normally, causing fuzzy or blurred vision. Other signs can include sweating, shaking, hunger, dizziness, weakness, headache, irritability, difficulty concentrating, or a fast heartbeat. Most people with hypoglycaemia notice blurred vision alongside other low-blood-sugar symptoms, although symptoms can vary.

Low blood sugar can happen after taking diabetes medicine or insulin without enough food, delaying a meal, drinking alcohol, or exercising more than expected. Blurred vision can also have other causes, so it should not be used on its own to identify hypoglycaemia.

If you have diabetes and think your blood sugar is low, stop driving or other risky activity and check your glucose if you can. Follow your personal hypo action plan. If you are awake and able to swallow, take a quick source of sugar recommended in that plan, then recheck your level after the interval your clinician has advised. Once recovered, eat a snack or meal if your next meal is not soon.

Do not give food or drink to someone who is drowsy, confused, having a seizure, or unable to swallow. Place them on their side, use prescribed emergency treatment if trained to do so, and call emergency services.

Get urgent help if blurred vision is accompanied by severe confusion, loss of consciousness, a seizure, inability to swallow, or symptoms that do not improve after following your hypo plan. Seek prompt medical advice if episodes keep happening, occur without diabetes treatment, or you cannot explain them. Sudden or persistent vision change also needs assessment because an eye or neurological problem may be involved.

Ask what glucose reading should trigger treatment for you, which fast-acting sugar to carry, and when to recheck after treatment. You can also ask whether your insulin or other diabetes medicines, meal pattern, alcohol use, or exercise routine could be contributing, and whether your vision needs a separate examination.