Low blood sugar levels aren’t always easy to spot. Here’s what to look for.

During a typical day, your blood sugar levels will vary naturally depending on a variety of factors, including your food choices, how much exercise you get (or don’t), the medications you take, your eating patterns, and stress in your life. But if your blood sugar falls too low and is not treated, it can cause serious health problems. There’s a name for that: Hypoglycemia is defined as the state where your blood glucose level drops so low that if you don’t take action to raise it to a normal level, your health may be at risk. Here’s what to know about this tricky condition—and how to spot signs before things get serious.

How Blood Sugar Works

When our body digests carbohydrates from the food that we eat, it is broken down into glucose, which is then released into the bloodstream. Meanwhile, your pancreas secretes insulin that helps move glucose from the blood into the cells to be used (or stored) for energy. When you have diabetes, your pancreas does not make enough insulin to transport glucose, so excess glucose remains in the bloodstream. This can cause long-term health conditions such as heart disease, kidney disease, and vision loss. But through a combination of nutrition and medication, you can control your blood sugar and minimize your risk for diabetes-related complications.

Types of Hypoglycemia

There are two main types of hypoglycemia: Reactive and fasting. Reactive hypoglycemia is low blood glucose that occurs after eating a meal (usually within four hours of eating). Fasting hypoglycemia occurs when the stomach is empty (like first thing in the morning, between meals, or after exercising). There are several factors that cause either type of hypoglycemia, including inadequate carbohydrate intake, going too long between meals and snacks, increased physical activity, alcohol, medications, surgical procedures, and illness. If you think you are having a hypoglycemic reaction, it’s important to take action.

Spotting Hypoglycemia Red Flags

The tricky part is that hypoglycemia may look different for everyone. “You have probably heard the definition of hypoglycemia as a blood glucose below 70 mg/dL,” says Christine McKinney, R.D., a registered dietitian and certified diabetes educator at Johns Hopkins University in Baltimore, MD. “But defining hypoglycemia on a glucose value can be problematic for some people.” Instead, says McKinney, hypoglycemia can be highly individual, based on your glycemic control. “For example, if your blood glucose is in the 300s and it drops to the 100s you may feel symptoms of hypoglycemia.” For this reason, it’s important to act quickly if you think you are having a hypoglycemic reaction.

Low Blood Sugar Symptoms

While each person’s reaction to low blood sugar may vary, signs usually include one or more of the following symptoms:

  • Feeling shaky, anxious, or nervous

  • Feeling lightheaded, dizzy, or faint

  • Intense hunger; chills, sweating, and feeling clammy

  • Rapid heartbeat

  • Confusion or clumsiness

  • Anger, irritability, or headaches

  • Nervousness or anxiety

  • Sleepiness, weakness, and lack of energy

  • Loss of color from the skin

  • Tingling or numbness in the mouth or face

McKinney advises, “If you feel any of these symptoms, test your blood sugar immediately, and know how to appropriately treat. Talk with your medical team and know your recommended blood glucose range.” If you are unable to check your blood sugar, you should assume it may be low and seek medical attention to avoid the risk of a more severe hypoglycemic reaction, including a loss of coordination, blurry or impaired vision, a loss of consciousness, or seizure.

How to Treat Hypoglycemia

To help stabilize your blood sugar levels, the American Diabetes Association recommends the 15-15 Rule: consume 15 grams of carbohydrate, wait 15 minutes, re-check blood glucose levels, and repeat as necessary until blood glucose is within a normal range. Examples of quickly digested carbohydrates include 1 tablespoon of honey, sugar, or corn syrup; one-half cup of fruit juice or regular soda; 5-6 pieces of hard candies or jellybeans; four glucose tablets; or tubes of energy gels. Once the level is normal, you should eat a meal or snack to avoid another hypoglycemic reaction.

How to Prevent Hypoglycemia

“Hypoglycemia can look and feel different depending on the person. Symptoms can include slow response times, feeling ‘foggy’ or light-headed, hunger, nausea, irritability, or anxiety,” says Kelly McGrath, R.D., a registered dietitian at the VA Medical Center in Baltimore, MD. “Some people may feel weak or have tingling of the lips or tongue. To prevent this, check your blood sugar regularly and maintain consistent carbohydrate intake throughout the day.” Take medications as prescribed and communicate with your health care team regularly so that medication adjustments can be made if needed.

Inconsistent carbohydrate intake and poor glycemic control can lead to sleep disturbances, says McGrath, including waking with symptoms that include shakiness and anxiety. “Hyperglycemia can also lead to nighttime wakefulness with urinary urgency—this one of the body’s ways of trying to get the excess sugar out of the bloodstream,” she adds. Talk with your healthcare provider if you are having any of these symptoms.

Research shows that older adults with cardiovascular disease or other chronic illnesses, and very young children with diabetes, are the most at risk for hypoglycemic reactions. But anyone can develop hypoglycemia—and just about everyone can be successfully treated for it, too. The key: recognizing the symptoms of this condition early and having a plan to manage them, so you can avoid progression to a more severe reaction, and keep on living your life.

Carmen Roberts, M.S., R.D., L.D.N.

Meet Our Writer

Carmen Roberts, M.S., R.D., L.D.N.

Carmen is a Registered Dietitian. In addition to writing for HealthCentral, she has spent her career working at Johns Hopkins and is also an adjunct faculty instructor for Excelsior College. Carmen has over 20 years of


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