Sneaky Signs Your Blood Sugar May Be Low, According to a Doctor and Dietitian

A lot of attention is paid to the dangers of chronically high blood sugar as it relates to your overall health. But low blood sugar can also be problematic. Knowing the sneaky signs of low blood sugar can help you take any necessary action to bring your blood sugar back to healthy levels.

Meet the experts: Courtney Pelitera, M.S., R.D.N., C.N.S.C., a registered dietitian nutritionist at VNutrition; Brooke Bussard, M.D., a lifestyle medicine health coach.

“Low blood sugar, or hypoglycemia, can put you at risk for some serious health complications if left untreated,” says Courtney Pelitera, M.S., R.D.N., C.N.S.C., a registered dietitian nutritionist at VNutrition. That’s because, as much as we want to prevent blood sugar from getting too high, our bodies do need it. “Blood sugar, or blood glucose, is the body’s primary fuel source, especially for the brain. When levels drop too low, the brain doesn’t get the energy it needs,” explains Brooke Bussard, M.D., a lifestyle medicine health coach. This can lead to unpleasant symptoms or, in more severe cases, can become a medical emergency, Dr. Bussard adds.

While it may seem counterintuitive, people with diabetes, especially those taking insulin or certain other glucose-lowering medications, are at the highest risk for hypoglycemia, says Dr. Bussard. People who take insulin are at risk for overdosing on insulin (either accidentally or on purpose), which can cause blood sugar to drop too low. But people with diabetes aren’t the only ones who need to be aware of the possibility of low blood sugar. “People who exercise at a high intensity for long periods of time without supplementing with food or carbohydrate-rich beverages are also at risk for hypoglycemia,” Pelitera says. Going long periods without eating, drinking alcohol on an empty stomach, taking certain medications, some hormone deficiencies, and some chronic illnesses can also cause low blood sugar, according to the Mayo Clinic.

So, what does low blood sugar look like? When your blood sugar drops too low, you’ll likely experience some pretty noticeable symptoms. “Common signs of low blood sugar include shakiness, sweating, headache, and feeling lightheaded,” says Dr. Bussard, all of which are caused by the brain not getting enough energy. But not all symptoms of low blood sugar are so recognizable. “Some symptoms can be more subtle, such as irritability, sudden fatigue, difficulty concentrating, blurred vision, or feeling anxious or unusually emotional,” Dr. Bussard adds.

In addition to these short-term symptoms, there are other more serious ones that can result from untreated chronic hypoglycemia. “The most common symptoms seen are alterations in mental status, confusion, muscle cramping, and cardiovascular effects such as tachycardia and bradycardia (alterations in heart rate),” says Pelitera. “More serious complications include a total body stress response, affecting hormones such as insulin, glucagon, cortisol, and growth hormone.”

Before you take steps to raise your blood sugar, it’s important to confirm that it’s low (especially if you have diabetes). “The most reliable way to confirm low blood sugar is to check with a glucometer, which measures your blood glucose using a small finger prick,” says Dr. Bussard. If you’re experiencing symptoms and can’t check, take a minute to review your day. Is there a chance you took too much insulin, or has it been too long since you last ate? If low blood sugar seems to fit as the cause of your symptoms, have a simple sugar snack.

“A common guideline is the 15–15 rule,” says Dr. Bussard. “Consume about 15 grams of simple carbohydrates, such as four ounces of fruit juice or a tablespoon of maple syrup, then recheck your blood sugar after 15 minutes. If it’s still low, repeat the process.” Waiting 15 minutes before rechecking your blood sugar or reevaluating your symptoms is key, as you need to give the sugar time to make its way to your bloodstream. “It is important for diabetic patients to not overcorrect the low blood sugar levels,” Pelitera notes. Then, once your blood sugar levels return to normal, Dr. Bussard says it’s helpful to follow up with a snack that contains protein and fiber.

Even though low blood sugar is easy to correct in the moment, chronically low blood sugar can be damaging to your health. If you experience these symptoms often, whether you have diabetes or not, it may be worth a chat with your healthcare provider to determine if you should take additional action to maintain stable blood sugar levels.