What You Need to Know About Hypoglycemia Unawareness
Before he was diagnosed with type 1 diabetes, Carlos Martinez had never run a race. But the diagnosis stirred something in him, a desire to persevere. “I saw it as an opportunity to see how far I could push the limits of what my body can do,” says Martinez, a lawyer in Santa Clara, California, who was 40 at the time. Seven months after that diagnosis, in 2012, he competed in his first triathlon, a 51.5-mile race that included cycling, swimming, and running.
But the following year, during the bike portion of a half Ironman (a 70.3-mile triathlon), he began to wobble wildly and lose his balance. After checking his blood glucose, he found he had unknowingly dropped to a dangerous level. He treated the low and finished the race, but he was eager to share what had happened with his doctor. When they spoke a few days later, Martinez had his answer.
He had hypoglycemia unawareness.
Seen and Unseen
Hypoglycemia is defined as three things occurring together: blood glucose below 70 mg/dl, the presence of low blood glucose symptoms (more on that later), and a relief of symptoms after you eat fast-acting carbs, such as glucose tablets. People who take insulin or certain type 2 meds (such as sulfonylureas or meglitinides) are at risk for hypoglycemia. Your risk for lows increases if you take one or more of these drugs and eat less than usual or are more active than usual without adjusting your medication. You may also become hypoglycemic if you drink alcohol without eating (see p. 98 for how to safely drink with diabetes).
“It’s a very serious matter when blood sugar gets low,” says Adrian Sandra Dobs, MD, MHS, an endocrinologist with Johns Hopkins Clinical Research Network. “The brain needs sugar to think, so this can eventually lead to seizures and even death.”
Usually, hypoglycemia comes with a range of symptoms. Sweating, shakiness, anxiety, heart palpitations, irritability, confusion, dizziness, fatigue, headaches, blurred vision—these are all signs that your blood glucose has dropped below healthy levels. The term severe hypoglycemia refers to the need for help from others to treat a low because of altered mental function, which can range from confusion and bizarre behavior to seizures and coma. (Here's a full list of hypoglycemia symptoms.)
With hypoglycemia unawareness, however, the early warning symptoms of hypoglycemia are minimized or nonexistent. Why? The problem arises when you experience frequent lows over time. It takes a progressively lower blood glucose level to set off the warning symptoms as time goes on. With each hypoglycemic episode, the threshold blood glucose at which your brain produces warning symptoms falls—until the early warning symptoms disappear altogether. In Martinez’s case, his tight blood glucose management increased his risk for hypoglycemia. The time frame for the development of hypoglycemia is different for everyone. Strict avoidance of lows can restore warning symptoms, but hypoglycemia unawareness can sometimes become a permanent condition.
Hypoglycemia unawareness affects roughly 25 to 30 percent of adults with type 1 diabetes, according to a study published in 2013 in the Indian Journal of Endocrinology and Metabolism. Less than 10 percent of adults with type 2 experience hypoglycemia unawareness, though a study published in 2015 in the Journal of Diabetes Science and Technology found that it may be more common in people with type 2 than previously thought. Its likelihood increases among those who have had diabetes longer because they’ve had more time to experience lows.
Cause for Alarm
Unrecognized lows can be dangerous in a number of situations. Driving can be a high-risk activity when you can’t recognize hypoglycemia symptoms; you might get dizzy, disoriented, or even pass out behind the wheel. Martinez wears a continuous glucose monitor (CGM) that will sound an alarm if his glucose drops too low, letting him know he needs to pull over and check his levels.
Exercise, too, can become tricky, as physical exertion lowers blood glucose. Many people with hypoglycemia unawareness rely on a CGM to monitor their glucose levels while they work out. But the devices aren’t practical for all activities. Triathlons are particularly tricky for Martinez. “The hardest part is open-water swimming,” Martinez says. “My CGM does not work in the water, carrying [fast-acting glucose] is hard to do in a wetsuit, and, of course, if you have a low blood sugar event in the water, that can be a real problem [because you may be far from shore].”
To stay safe, check your blood glucose before exercise and treat accordingly if it’s trending low. You may need to pause your activity to do a finger-stick blood glucose check. And always carry fast-acting glucose (such as tablets or gels) with you when you exercise.
Finding a Balance
Despite the dangers, there are a number of ways to manage hypoglycemia unawareness, and it’s even possible to reverse the effects and restore symptoms of hypoglycemia.
Raise Your Targets
The first step in managing hypoglycemia unawareness is to identify the level at which you begin to notice your blood glucose dropping. People typically begin to feel symptoms at a blood glucose around 60 or 70 mg/dl. If you don’t feel a low until you’re at 50 mg/dl or lower and are experiencing changes to your mental state, your doctor may recommend raising your target blood glucose range.
“You would want to modify glucose target ranges or A1Cs so that it’s not as tight or intense,” says David K. Miller, RN, BSN, MSEd, CDE, LDE, FAADE, a certified diabetes educator with Community Health Network in Indianapolis. “We want them to be free from low blood sugars over a period of time.” The goal is to avoid any hypoglycemic episodes so that the low blood glucose response system has time to recover. The longer you avoid lows the better, but a study published in 2012 in Endocrinology & Metabolism Clinics of North America found that symptoms can begin to return in as little as three weeks.
To avoid going low, Miller recommends keeping a diary of daily activities, food habits, and insulin schedules, which can help identify hypoglycemia triggers. Keep a spare batch of glucose tablets on hand at all times. It’s also possible for those around you to notice subtle signs of hypoglycemia—slight tremors, for instance—that you may miss. Miller suggests educating your friends, family, and coworkers on the symptoms of low blood glucose so they can be extra attentive. It’s also important that they know how to properly administer glucagon.
Preparing for sleep is also important. For most people experiencing a nighttime low, symptoms such as sweating and bad dreams may wake them in time to treat. But those with hypoglycemia unawareness run the risk of sleeping through low blood glucose. A CGM that sounds an alarm when your glucose is dropping can help wake you so you can treat with fast-acting glucose.
To reduce his chances of going low during sleep, Martinez carefully considers his meal choices each day. He checks his blood glucose before bed and, if low, takes steps to ensure he remains within a healthy range during the night. “I try to make sure I’m right around 120 or 150 when I go to sleep,” Martinez says. If your glucose is on the lower side of normal before bed, snacks with a mix of carb, fat, and protein can help sustain you overnight. Try half of a peanut butter sandwich or slow-release carbs from an Extend Nutrition bar.
Frequently Check Glucose Levels
A CGM that sounds an alarm can be invaluable for people with hypoglycemia unawareness. It’ll alert you when your glucose level dips or is trending downward, and some devices can send alerts to loved ones. “If they do live alone, or if it’s a kid in college, Mom can get it on her cell phone and then call the roommate to intervene early,” Miller says. “For little kids, too, who don’t know how to recognize low blood sugars, the CGM can help because [the alert] can go to Mom’s phone.”=
Certain devices, such as Medtronic’s insulin pumps and the Tandem X2 pump, can also be useful tools. By automatically suspending insulin delivery when your glucose goes too low, these pumps can help prevent severe hypoglycemia.
While hypoglycemia unawareness can be dangerous, Martinez has never let fear keep him from lacing up his running shoes. “I train consistently, day in and day out, all year long,” he says. “I drink calories on the bike, I carry calories when I run.”