Low blood sugar, known as hypoglycemia, can cause people to feel jittery, sweaty, confused, sleepy and lightheaded. It mostly affects people with diabetes, but you don't have to be diabetic to experience it. And it is often related to what you eat.
Eat Smart to Prevent Lightheadedness
According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), low blood sugar occurs when a person's glucose (sugar) levels drop below normal levels. That's often considered to be 70 milligrams per deciliter or less.
If you have diabetes and are experiencing dizziness, the cause could be your insulin shot or other diabetes medications. For some, it has to do with the specific food you eat or the time you eat it. Skipping or delaying a meal can cause blood sugar levels to plummet, according to the NIDDK. Drinking too much alcohol without food in your stomach can also cause this. In each case, though, the solution is simple.
"Eat or drink something," says Lona Sandon, PhD, RDN, program director and associate professor in the Department of Clinical Nutrition at University of Texas Southwestern Medical Center at Dallas. "If your lightheadedness is truly caused by hypoglycemia because you have not eaten in several hours, the answer is simple: Eat something."
In a pinch, "hypoglycemia is most quickly corrected with about 15 grams of carbohydrate," Sandon says. A half-cup of juice is one example, she adds.
Of course, if dizziness attributed to a sugar low is driven by alcohol, make sure to take in some food before you reach for that next alcoholic drink, suggests the NIDDK. That's important because if you've been drinking, your body has a harder time keeping your blood sugar steady, especially on an empty stomach, it says.
If Sugar Dips After You Eat
If you don't have diabetes and get dizzy after eating, you might actually be experiencing a post-meal condition known as reactive hypoglycemia. According to the Mayo Clinic, this is when blood sugar plummets right after a meal. It typically happens within four hours after eating, and it can spark shakiness, sweating, confusion and lightheadedness.
It's not always clear why this happens. While it may have to do with what you eat, it could also be about when you eat, according to the Mayo Clinic. At the same time, your risk goes up if you've recently undergone certain operations — like gastric bypass — or if you're genetically prone to metabolic disorders.
The good news is that if you get dizzy and lightheaded because of a post-meal blood sugar drop, it usually doesn't last long. And medical treatment is rarely required.
Read more: The Best Diet for Reactive Hypoglycemia
How to Lower Your Risk
There are steps you can take to make blood sugar dips less likely. "In general, consuming protein and high-fiber foods—such as whole grains, vegetables, fruits, legumes and nuts—with meals and snacks can help reduce the effects of reactive hypoglycemia," says Samantha Heller, MS, RD, a senior clinical nutritionist with NYU Langone Health.
Hummus and vegetables, a banana and peanut butter sandwich, or a spinach and bean burrito are all good options, "and avoid meals or snacks that are primarily easily digestible carbohydrates, such as chips, cookies, juices, candy, crackers, muffins or waffles," she says. "These kinds of meals can cause a spike, followed by a crash in blood sugar, which can cause symptoms of hypoglycemia."
The best way to prevent a low blood sugar episode of dizziness is "to include protein, fat and carbohydrate in a balanced meal," Sandon says. "This helps slow down the release of carbohydrates into the blood, and lessens the insulin response to some degree." Also avoid sugary foods like candy, soft drinks and honey, she warns, because all those foods can be a problem "if you are someone prone to reactive hypoglycemia."
Anyone who feels that reactive hypoglycemia is an ongoing and recurring problem should see their doctor to determine the cause, Heller advises. Your doctor will rule out diabetes and other causes by checking your blood glucose level, the Endocrine Society explains.