High blood sugar gets a lot of attention and rightfully so, since diabetes affects more than 10% of our population. Yet, low blood sugar is often misunderstood—and this concerns me greatly.
Low blood sugar (hypoglycemia) is one of the serious complications of diabetes, especially for anyone who is on insulin, and that includes a surprisingly large percentage of patients with type 2 diabetes. Low blood sugar also occurs in people who don’t have diabetes. Although this type—called reactive hypoglycemia—rarely causes severe problems, it can make you feel awful.
Because the symptoms of hypoglycemia are not specific to low blood sugar, they are often chalked up to other causes or ignored altogether. Furthermore, patients, especially those who are on insulin, aren’t always aware when blood sugar drops too low. Therefore, rather than focusing on causes, prevention, and treatment, which I have covered in detail in other articles, let’s discuss the signs and symptoms of low blood sugar.
What Happens When Your Blood Sugar Is Too Low?
Your cells depend on glucose, a simple sugar derived primarily from dietary carbohydrates, to generate energy. Hypoglycemia occurs when glucose in your blood falls too low, due to an excessive dose of insulin, reactive hypoglycemia related to poor diet, or other factors.
When your sugar level drops too low, your adrenal glands pump out hormones that play a key role in your body’s stress response. The stress response is a well-recognized series of reactions initiated whenever your body senses an immediate threat of any kind. It could be a near-accident in your car, a heated argument, or a potentially harmful change in physiology—and low blood sugar is most certainly potentially harmful.
These hormones raise the concentration of blood glucose and, at the same time, trigger additional reactions that affect organs and systems throughout the body. It is important that you are tuned in to these reactions because they can serve as a warning sign that your blood sugar is too low.
Cardiovascular Effects of Hypoglycemia
One of the stress hormones released when blood sugar falls too low is adrenaline, and its main purpose is to get you ready for “fight or flight.” Granted, increasing blood sugar doesn’t require fighting or fleeing—few of the perceived threats we face today do. But the stress response doesn’t pick and choose. Any stressor sets off the whole cascade of physiological reactions. It’s all part of an automatic survival mechanism that has served us well throughout the eons.
In addition to mobilizing stored glucose to ensure a quick burst of energy, adrenaline increases muscle tension, heightens mental alertness, and primes your cardiovascular system to get you ready for action. That’s why low blood sugar can cause an elevated heart rate, sometimes accompanied by heart palpitations (strong or irregular heartbeats).
The rapid heart rate, palpitations, and other symptoms subside after blood sugar returns to normal. However, there may be long-term cardiovascular consequences. Diabetes is linked with an elevated risk of heart attack, stroke, and premature death. Severe and/or repeated episodes of hypoglycemia amplify this risk.
How Low Blood Sugar Affects Your Brain
Your brain weighs only three pounds, but it consumes 20% of your body’s energy resources—and when it doesn’t get enough fuel (glucose), it cannot function at its peak. So, it’s no coincidence that drowsiness, poor concentration, and headaches are common symptoms of hypoglycemia.
If blood sugar remains low and the brain is increasingly energy-starved, things go downhill fast. Severe or prolonged episodes of low blood sugar can make you feel dizzy, confused, and unable to think and speak clearly—plus, they are linked with an increased risk of developing dementia. In the most extreme cases, which are blessedly rare, low blood sugar can cause seizures, coma, and even death.
It isn’t just the lack of glucose but also the surge of adrenaline that affects your brain. Part of the fight-or-flight response is hyper alertness to sights, sounds, and other stimuli. When your blood sugar level drops too low, you may be easily distracted and find it hard to focus on the task at hand. You may feel nervous and shaky, irritable, and anxious—all these symptoms are due to adrenaline.
Have You Ever Been Hangry?
Along with the moodiness, jitteriness, and anxiety that low blood sugar can cause, you may feel hungry as all get-out. You don’t just want to eat—you want to eat right now! You’re hangry.
“Hangry” is a word added to the Oxford English Dictionary in 2018 and defined as “bad-tempered or irritable as a result of hunger.” It’s a perfect description of the food cravings and mood changes related to hypoglycemia. Once you eat something and get your blood sugar back up, these symptoms subside.
I have been asked if other digestive symptoms could be signs of hypoglycemia. For example, can low blood sugar cause nausea and vomiting? How about diarrhea or constipation? Hypoglycemia-related hunger and food cravings could be accompanied by hunger pains and nausea, but low blood sugar doesn’t typically trigger other gastrointestinal problems.
Be Aware of Hypoglycemia Unawareness
As you can see, the warning signs of low blood sugar could be attributed to any number of conditions—from heart problems to chronic anxiety to poor sleep. That’s why I recommend that if you experience these symptoms, work with your doctor to rule out hypoglycemia.
This is especially important for anyone with diabetes—and critical for those who are treated with insulin. A 2020 study found that a quarter of patients who have been on insulin for more than five years have severe hypoglycemic events. Unfortunately, they don’t always recognize when their blood sugar is low.
“Hypoglycemia unawareness,” as this is called, is a relatively common and serious problem in insulin-treated diabetes. Talk to your physician about factors that increase this risk, which include nighttime hypoglycemia, memory problems, recurrent hypoglycemic episodes, advanced age, and adrenal fatigue.
Get familiar with all the signs and symptoms of low blood sugar and how to prevent and treat it. Mild hypoglycemia may make you tired and cranky, but more severe episodes—which are an often-neglected complication of diabetes—can have serious short- and long-term consequences.