Can low blood sugar cause double vision

By Melissa Johnson and Moira LawlerMedically Reviewed by Kacy Church, MD

Reviewed: March 19, 2021

As a person living with diabetes, you know how important it is to reduce blood sugar when it is too high, a phenomenon called hyperglycemia. But blood sugar that is too low, or hypoglycemia, is equally critical to avoid.

"Hypoglycemia happens when the amount of blood glucose (sugar in the blood) drops to a level that's too low to sustain normal functioning," says Erin Palinski-Wade, RD, CDCES, who is based in Sparta, New Jersey. "In most people, this is defined as a blood sugar level at or below 70 milligrams per deciliter (mg/dL)."

Hypoglycemia is common among people with type 2 diabetes, according to a review published in June 2015 in the journal PLoS One. Individuals with the condition had an average of 19 mild or moderate episodes of hypoglycemia per year and nearly one severe episode per year on average, according to the researchers. Low blood sugar was particularly common among those taking insulin.

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This decrease in blood sugar levels can cause both short-term complications, like confusion and dizziness, as well as more serious issues, including seizures, coma, and, rarely, death, according to the American Diabetes Association (ADA).

Hypoglycemia is usually the result of a too-high dose of insulin or a change in diet or exercise habits, according to Harvard Health Publishing.

To prevent hypoglycemia and its potentially dangerous side effects, monitor your blood sugar levels and treat low blood sugar as soon as you become aware of it, recommends the Mayo Clinic.

Also, pay attention to these telltale signs of dipping blood sugar levels to make sure yours stays under control:

1. Ravenous Hunger

If you suddenly, inexplicably feel as if you're starving, your body is signaling that it’s experiencing a blood sugar drop, according to the Cleveland Clinic. You can manage your blood sugar by counting your carbohydrate intake. A good starting point is the ADA's recommendation to eat between 15 and 20 grams (g) of carbohydrates with each snack and between 40 and 65 g at each meal, though you should work with your dietitian or certified diabetes care and education specialist to determine what’s right for you.

2. Feelings of Anxiety

When glucose levels fall too low, your body releases the hormones epinephrine (also called adrenaline) and cortisol, which signals the liver to release more sugar into the blood, according to Merck & Co. That can lead to anxiety and its associated symptoms, such as shakiness, sweating, and heart palpitations, according to research published in July 2016 in Case Reports in Psychiatry.

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3. Restless Nights

Nocturnal hypoglycemia, which accounts for about half of all low blood glucose episodes, can cause a number of sleep disturbances, according to Johns Hopkins Medicine. "Symptoms include night sweats, nightmares, episodes of waking suddenly and crying out, and feelings of unrest and confusion upon waking," says Palinski-Wade. "A snack before bed can reduce the frequency and severity of sleep disturbances." Ideally, your blood sugar reading should be between 90 and 150 mg/dL before rest, according to Joslin Diabetes Center.

4. Shakes and Tremors

Shakiness is a symptom that occurs when the autonomic nervous system is activated during hypoglycemia, according to previous research.

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5. Emotional Instability

Mood swings and sudden emotional episodes not typical of your normal behavior are among the neurological symptoms of hypoglycemia and can include irritability, stubbornness, and feelings of depression, according to research.

6. Sweating

Sweating is usually one of the first signs of hypoglycemia and, as mentioned, occurs as a result of adrenaline, which increases as glucose levels drop, according to a 2017 article in Practical Diabetes. Up to 84 percent of people with diabetes experience sweating when they’re hypoglycemic, according to the research. Check the back of your neck for sweating. According to Kaiser Permanente, it’s almost always present during low blood sugar episodes but should go away shortly after you take in some sugar.

RELATED: What to Do When Blood Sugar Levels Drop Too Low

7. Lightheadedness

When your blood sugar is low, your brain tries to preserve as much energy as possible, so you may feel lightheaded as a result, according to Harvard Health Publishing. If you experience this common symptom of hypoglycemia, treat the hypoglycemia quickly with 15 to 20 g of fast-acting carbs, such as juice, suggests the Mayo Clinic. Try to lie down, too, and if the lightheadedness keeps up for more than 15 minutes, it’s time to seek medical help, suggests Harvard.

8. Difficulty Concentrating

The brain relies on blood sugar for energy, so if there’s a drop in glucose, your brain may not function properly, according to Harvard Health Publishing. That can make it difficult to concentrate on one thing at a time. The good news is there doesn’t appear to be any long-term brain damage caused by moderate hypoglycemia episodes, according to a past review.

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9. Vision Problems

If you suddenly start experiencing vision problems, a drop in blood sugar may be the culprit. According to a past case report, blurred vision is the most common eye-related symptom (affecting 73 percent of study participants), followed by dimness in vision (about 45 percent) and black spots (37 percent).

10. Slurred Speech and Clumsiness

Your sugar-starved brain may change the way you sound. Slurred speech is a common symptom associated with blood sugar levels that drop below 40 mg/dL, according to University of Michigan Health Systems. Combined with clumsiness — another sign of low blood sugar —  you may seem as though you've had a few too many cocktails, even if you haven't touched a drop, according to the National Health Service.

RELATED: Hypoglycemia Unawareness Is Common in People With Type 2 Diabetes, Research Suggests

For more on managing low blood sugar, check out Diabetes Daily's article "How to Treat Lows Without Sabotaging Your Diet!"

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