The bottom line: lows are something to be avoided. There is no advantage whatsoever to experiencing hypoglycemia. Sure, frequent lows can reduce your A1c and give the appearance of “good management.” But as my wife so eloquently reminds me from time to time, “Any idiot can have a decent A1c if they’re taking too much insulin and going low all the time!”
Mild Lows
Soon after diabetes is diagnosed, the brain can detect hypoglycemia quickly and easily. In some cases, symptoms can occur even at blood sugars above 70 (3.9). Blood sugars in the 80s or 90s (4s, 5s), or a rapid drop from a very high level toward a more normal level, may induce hypoglycemic symptoms.
Upon sensing that the blood sugar is low, the brain sends a signal to the adrenal gland, which releases a surge of adrenaline.
Adrenaline, in turn, stimulates the liver to secrete extra sugar into the bloodstream and opposes the action of insulin.
Adrenaline also causes a number of physical symptoms: rapid heartbeat, perspiration, shaking, hunger, and a generally anxious feeling. (You may recognize these as the same symptoms that occur when you are under intense stress, like when your in-laws call to tell you they’re coming to visit and will be there in an hour.) When experiencing a mild low, most people are capable of thinking rationally and consuming carbohydrates in order to raise their blood sugar level.
Moderate Lows
If blood sugar levels are allowed to drop into the 50s or 40s (3, 2 mmol/l), the brain begins losing the ability to function properly.
Confusion usually sets in, accompanied by dizziness and weakness.
Your speech may become slurred, your vision blurry.
You may exhibit unusual emotions such as irritability or despair.
You will have a difficult time thinking clearly and coordinating your movements.
At this point you can still consciously take food or drink to treat the low, but you may require some assistance from a friend or family member.
Severe Lows
An extreme or extended low may cause you to pass out or experience a seizure. Very severe, prolonged lows can result in coma or death. Severe lows, by definition, require outside assistance and are usually treated with an injection of glucagon or an intravenous infusion of dextrose.
The Devolution of Symptoms
No, it’s not a typo. And it has nothing to do with the band Devo (“Whip It,” circa 1980). The symptoms of hypoglycemia do not evolve: they devolve, or break down, over time. The brain actually becomes
more efficient at extracting glucose from the bloodstream after surviving years of low episodes.
This is an adaptive response by the brain, something like when people’s lungs adapt to high altitudes after being there for a while.
As a result, the brain ceases to detect mild low blood sugars.
Little or no adrenaline is produced, and physical symptoms (shaking, sweating, and so forth) fail to take place.
Thus, there may be no warning of low blood sugar in its early stages.
The first symptoms are those of a
moderate low blood sugar (such as confusion), and these may not occur until the blood sugar has reached a dangerously low level.
The name given to this phenomenon is “hypoglycemia unawareness.” It affects most people who have had diabetes for several years and tends to become worse over time. The more lows you have, the less likely you are to experience any warning signs the next time a low occurs. Quite a paradox!
Research has shown that the early symptoms of low blood sugar can, to some extent, be restored by avoiding going below 80 (4.4) completely over a period of several weeks. Although this may produce a temporary rise in the HbA1c level, it is well worth it to be able to detect lows and prevent severe hypoglycemia. Look for strategies for preventing hypoglycemia later in this chapter.
Treatment of Lows
Diabetes is a tricky disease.
Lows sometimes feel like highs, and highs sometimes feel like lows.
If you suspect that your blood sugar is low, take a few seconds to confirm by glancing at your CGM or checking with a meter.
I can’t tell you how many times I thought I was low, only to check and get a reading in the 200s or 300s (teens to 20s).
High blood sugars can cause symptoms similar to those caused by lows (tiredness, hunger, a jittery feeling).
If you are low, getting an exact reading is also helpful for determining how much carb you need to treat the low.
CGM users should be aware that most, but not all, CGM systems are reasonably accurate in a hypoglycemic range. Check the performance of your particular system by looking up how often it is within 10 mg/dl (0.6 mmol/l) of the lab value when the glucose is in a normal-to-low range. This information can usually be found in the technical section of the user guide. If yours is within 10 (0.6) points less than 90 percent of the time, consider doing a fingerstick each time before treating.
With premeal blood sugars that are below your target but above 70 mg/dl (3.9 mmol/l), reducing your meal bolus using your correction formula is a sound approach. This is commonly called a “reverse correction” (deducting from the meal dose so that the blood sugar will rise a little bit). For readings below 70, you should treat the low immediately, wait ten to fifteen minutes for the blood sugar to come up, and then have your meal (giving the usual dose for your meal). If you eat to treat the low
and reduce your mealtime bolus, you will have double treated and will probably wind up quite high.
There is no one-size-fits-all when it comes to treating lows.
There is no one-size-fits-all treatment for hypoglycemia. Proper treatment depends on a number of factors, including: