Hypoglycemia: 10 Signs of Low Blood Sugar

by Erin L. Boyle Health Writer

You’ve seen that Snickers commercial with Betty White, right? Where she’s transformed into a man so mad with hunger that only chomping on the candy bar can return her to normal? Turns out, the commercial is spot-on when it comes to hypoglycemia (low blood sugar), which is defined as blood glucose below 70mg/dL. It’s an uncomfortable and sometimes a life-threatening condition. If you have repeated episodes of hypoglycemia, or if your sugar level is too low, you need to act fast to avoid serious problems. For most of us, though, the treatment is as the commercial indicates: Down some quickly digested carbs like fruit juice or raisins. In the meantime, get familiar with the other signs of hypoglycemia.

Man suffering from dizziness with difficulty standing up while leaning on wall

You Feel Like You Might Pass Out

If you suddenly feel weak, shaky, or lightheaded—or if you even faint—you could be experiencing hypoglycemia. A headache that comes on quickly, weakness or tremor in your arms or legs, and a slight trembling of your body are also signs that your blood sugar is too low. To get back to a more normal sugar level, eat something with sugar, such as pure glucose in the form of tablets or gel, for example. If it’s not urgent (you don’t have diabetes), go to the carbohydrates.

woman eating burger

You Feel Super Hungry

Some people call it “hangry”—that intense hunger with low blood sugar that makes you feel a bit crazed. Ginger Vieira, 33, who has type 1 diabetes, says “severe lows can make you want to eat everything in sight.” The reason? Counter-regulatory hormones known as glucagon, cortisol, and adrenaline, says Siripoom McKay, M.D., assistant professor of pediatrics, diabetes and endocrinology at Baylor College of Medicine in Houston, TX. When you're hypoglycemic, these chemicals surge to counteract insulin and get your blood sugar back up. In the meantime, they can make you feel like you’ll starve if you don’t eat all the food—immediately.

young man outside, wiping brow from sweat

You're Clammy and Sweaty—for No Obvious Reason

With hypoglycemia you may break out in a cold sweat even though you’re not overheated, and you may get pale and feel clammy. This happens because low blood-sugar levels trigger the body’s fight or flight response and the release of adrenaline, a hormone. This adrenaline burst causes sweating along with other symptoms. People with type 1 diabetes commonly feel damp and sticky from hypoglycemia at intervals throughout a given week.

senior woman clutching heart sitting outside

Your Heart Is Racing

The extra adrenaline released during hypoglycemia can also cause your heart to beat fast or irregularly, which you may feel as palpitations or as a pounding sensation in your chest. Johnson says he’s used to feeling his heart racing when his blood sugar is low. A caution from Betul Hatipoglu, M.D., at the Cleveland Clinic in Ohio: Take extra care to properly treat any other heart condition, since the added effect of a fast or irregular heartbeat with hypoglycemia can make both conditions worse.

You Feel Confused and Out of Sorts

With hypoglycemia, all of your cells hunger for fuel, including your brain, says Kathleen Wyne, M.D., Ph.D, director of the Ohio State University Adult Type 1 Diabetes Program in Columbus. As a result, you may feel spacey and confused, and you may have trouble communicating. With diabetes, ask friends and family to generally stay alert and ask, “Hey, are you struggling to talk right now?” advises Janet G. Zappe, R.N., a clinical program manager for the Diabetes Research Center at The Ohio State University Wexner Medical Center.

close up of hand erasing pencil

… and You're Making Mistakes Left and Right

Keep screwing things up? Maybe you’ve made a computer error. A speaking error. A calculation error. You can’t seem to get back on track. Stop whatever you're doing to regroup and consider that hypoglycemia might be to blame, says Dr. Wyne. “A dramatic example of this is getting in your car and driving somewhere, then an hour or two later not knowing how you got there. Even if you realize your levels are low, you may not be able to think clearly enough to do something correctly.”

Young man getting angry on the road

You're Extra Irritated and Angry

Is your level of frustration a 20 out of 10? Angry and anxious for no obvious reason? It could be hypoglycemia. “The most common mood changes are being belligerent and argumentative,” says Dr. Wyne. “Or it could be more subtle in just refusing to discuss something or not agreeing to something that is normally acceptable to you,” she says. If your partner tells you you’re crankier than usual, take note. Personality changes like Betty’s a major sign of hypoglycemia, agrees Zappe.

young woman, half in shadow

You Feel Anxious and Unsettled

Extremely low blood sugar can cause anxiety because the brain isn’t getting enough fuel and you may fear what happens next. Johnson knows it’s time to check his glucose when these sensations start to creep up. Diagnosed with type 1 diabetes when he was age 5, he’s used to the anxiety bubbling up, but isn’t always successful at keeping the feelings at bay. “I work hard to manage my blood sugars, but diabetes is complicated and the tools we have are no match for a fully functioning endocrine system that can regulate things naturally,” he says.

You Feel Suddenly Tired or Sleepy

If you have diabetes and suddenly feel tired, or overwhelmingly sleepy, it can be a sign that your blood sugar is low, and your body is not getting enough energy. Rather than taking a nap—and the risk that your hypoglycemia episode will worsen–eat something, drink that juice, take your glucose tablets or gel. This isn't a time to lie down and go to sleep, no matter how much you may want to.

woman in cafe drinking orange juice

What to Do

With hypoglycemia, time is of the essence. Eat foods that deliver sugar quickly, and you’ll feel much better. And if you have diabetes, turbo-charge your preparations given that an extreme blood-sugar drop that can happen. A study published in the Indian Journal of Endocrinology and Metabolism said that “acute interruption” of glucose supply to the brain could result in functional brain failure and coma or death; we have four minutes to treat before brain cells start dying. Yep, that's totally scary, but it's also crucial information to know. With diabetes emergencies, a rescue medication called glucagon (a hormone) can be used to turn things around. Ask your doctor if it's right for you.

Erin L. Boyle
Meet Our Writer
Erin L. Boyle

Erin L. Boyle, the senior editor at HealthCentral from 2016-2018, is an award-winning freelance medical writer and editor with more than 15 years’ experience. She’s traveled the world for a decade to bring the latest in medical research to doctors. Health writing is also personal for her: she has several autoimmune diseases and migraines with aura, which she writes about for HealthCentral. Learn more about her at erinlynnboyle.com. Follow her on Twitter @ErinLBoyle.