For a newly diagnosed type 1 diabetic, there is nothing scarier than having your blood sugar bottom out. One minute you’re fine, the next you’re sitting in a pool of your own sweat trembling and struggling to put a coherent thought together.
But as you go through the years with this condition, you start to realize that as bad as suffering through those hypo symptoms are, not having them is a heck of a lot worse. If you’ve ever done a routine finger poke only to have the monitor be the first to inform you that your blood sugar is frighteningly low, then you understand what I mean.
While many long-term diabetics have some idea of what hyperglycemia unawareness is, most don’t have a full grasp of why this condition appears or how you can work to avoid or even reverse it.
What Is Hypoglycemia Unawareness?
As the name implies, hypoglycemia unawareness (HU) is the inability to tell when your blood sugar is low. On a more scientific level, HU is the onset of a shortage of glucose in the brain before autonomic warning symptoms occur.
In someone with normal hypo awareness, lowered blood sugar, usually around 70mmol/l, sets off a chain reaction in the body meant to help increase blood sugar levels while causing physical symptoms that will alert the individual to the problem.
Unfortunately, the normal channels for automatically increasing blood sugar levels don’t work well in insulin-dependent diabetics. This has to do with changes in hormone pathways as well as the presence of insulin in the bloodstream preventing the release of glucagon.
Because of this, diabetics need to take in glucose manually to increase their blood sugar levels. By responding to symptoms like sweating, shakiness, anxiety, dizziness, and palpitations, people with diabetes can usually normalize their blood sugars before dangerous symptoms set in.
But for someone with HU, the lack of autonomic symptoms can make very difficult to know when blood sugars are plummeting. This can lead to cognitive impairment or loss of consciousness before the person is even aware there is an issue.
While some patients with HU will only get minor symptoms of lows or only show symptoms at very low blood sugars, others may not show any signs until it is too late to help themselves.
What Causes Hypoglycemia Unawareness to Develop?
The exact mechanisms that cause hypoglycemia unawareness to develop are not completely understood.
There are some studies that support the idea that the brains of diabetics with HU compensate for frequent hypoglycemia by shutting down certain areas when glucose is too low. Some of these areas that are shutdown may be key to triggering symptoms in a healthy patient.
Others postulate that changes in glucose transport or metabolism in light of frequent lows allows the brain to function better during hypoglycemia, thus reducing the signaling pathways of autonomic symptoms.
There is also some evidence to suggest that the actual chemical makeup of the brain–such as increased levels of Gamma-aminobutyric acid (GABA) during low and normal blood sugars–changes over time as a result of hypoglycemia. These changes cause reduced sensitivity to low blood sugars and a reduction in symptoms.
Regardless of the underlying causes of HU, what we do know is that recurrent episodes of hypoglycemia result in less severe autonomic symptoms over time. In fact, a slight reduction of symptoms can even be seen after just a single episode of low blood sugar. And, as this study points out, you may not even be aware that you have suffered a hypo event, as diabetics are prone to asymptomatic lows during sleep.
But not everyone will react to repeat hypos with the same degree of desensitization. Certain genotypes appear to play a large role in the development of HU and women appear to be more frequently affected than men.
Who Is Most at Risk for Hypoglycemia Unawareness?
About 40% of type 1s have hypoglycemia unawareness.
- Of these, the majority have had diabetes for more than 20 years.
- The occurrence of HU in adolescents, however, is surprisingly high, especially in populations that were diagnosed before the age of six and have experienced severe episodes of hypoglycemia in the past.
- Seniors, as well, appear to be prone to suffering from HU. This has to do with a combination of being more likely to have had diabetes for a long time and the consequences of the natural degradation of cognitive function that comes with age.
Other risk factors for HU include lower A1C and past episodes of severe hypoglycemia that resulted in coma or hospitalization.
Can You Reverse Hypoglycemia Unawareness?
If you are someone who already suffers from HU, it is possible to improve your sensitivity to lows and even start feeling those autonomic symptoms again.
In one study, a group of insulin-dependent diabetics showing almost no autonomic symptoms during hypoglycemia were subjected to intense blood sugar management centered around the “scrupulous avoidance” of lows. After three days, all subjects showed improved symptoms, with completely normal autonomic reactions to lows after four weeks.
For people living with diabetes who aren’t part of a rigorous scientific study, completely avoiding lows can be close to impossible. After all, high blood sugars carry their own risks and can be much more difficult to avoid if your focus is only on not dropping too low.
Improvements in diabetes tech are making it more possible to reduce the occurrence of hypos without sacrificing tight control over blood sugars.
One of the best defenses against lows is the use of ever-advancing continuous glucose monitors (CGMs). Many of the CGMs on the market today can predict impending lows and alarm in advance to allow the patient to consume sugar or reduce insulin to avoid dropping below 70mmol/l.
CGMs combined with insulin pumps that are integrated and outfitted with ‘auto mode’ is also proving to be an excellent tool in reducing lows by constantly adjusting insulin levels in response to real-time CGM readings. See In-depth on Tandem’s Advanced Hybrid Closed-Loop System.
Of course, even with the best tools, no one perfectly manages their diabetes (nor should they expect to). Lows will happen. But with a focus on reducing the amount and severity of the hypos you suffer, you can reduce your risk of hypoglycemia unawareness and increase the odds that you continue to live a healthy, happy life as a type 1 diabetic.