By: Scott M. King
A word of caution about the values used below. This study was conducted using people without diabetes. Some people with diabetes experience symptoms at higher glucose levels than the study suggests. Other people with diabetes appear to function well with blood sugars in the 30’s and 40’s (mg/dl). Therefore, the values in the study should only be used as an approximation. This study also used plasma glucose levels. Your values done at home might be 20 percent lower or higher than these lab values. For example, epinephrine release in someone without diabetes would begin at about 63mg/dl with a home blood glucose meter.
More caution: Many people with long-standing type 1 diabetes completely lose some of these responses. The glucose counter-regulation system becomes impaired sometime during the first few years of diabetes. This impairment is unusual in that it seems to be hypoglycemia-specific: the ability of glucagon and epinephrine to respond to other stimuli is basically unchanged, but is reduced or absent when dealing with hypoglycemia. The cause of this is not known, but it is closely linked with the lack of insulin production.
HYPOGLYCEMIA, What Happens As Your Blood Glucose Levels Fall*:
at 69 mg/dl Epinephrine is released into the bloodstream
at 68 mg/dl Glucagon release begins
at 67 mg/dl The brain conserves glucose by reducing glucose uptake
at 66 mg/dl The body releases the growth hormone Somatotropin, which tells the body to reduce its use of glucose and burn fat instead
at 58 mg/dl Cortisol, a steroid that promotes the conversion of glycogen into glucose
at 54 mg/dl Full-on hypoglycemic body symptoms may start including shaking, pounding heart, nervousness, sweating, tingling and hunger
at 49 mg/dl Thinking becomes impaired. The Mind symptoms start: confusion, drowsiness, weakness, feeling too warm, difficulty speaking, impaired coordination and odd behavior
*Many type 1s don’t have all these responses.
In this age of tight control, hypoglycemia has become a major concern for people with diabetes. How much do you really know about it? This article details symptoms, causes, and the body’s responses to hypoglycemia. The more you know about hypoglycemia, its progression, and its causes, the more likely you will be to control or prevent it.
“I’m drenched in sweat and everything is getting on my nerves. My face feels tight and my lips feel numb. I know I should check my blood sugar, but I can’t think well enough to get it together. Finally I get my finger stuck, my blood drop on the strip, wait… Blood sugar reads 40mg/dl. I eat 4 Dex4’s and start to feel better in about 10 minutes. My health practitioner calls this hypoglycemia, but I call it pure hell.”
I know many type 1’s actually get used to this, and learn to feel, test and correct by eating very effectively. Others, like me, get the “Diabetic Werewolf Syndrome” where I have to keep eating everything in site until my blood glucose raises back up, usually about 20 or 30 minutes until we stop shaking. But of course every hypo can be different. I have friends that can get quit querulous when they are low. I have seen some skinny type 1’s who, when low, may even “fight off” a husband who tries to get them to eat. Many of us have spent our whole lives AVOIDING Sweets, so their subconscious eschews sweet even when low. Everyone had heard of some Low diabetic doing something REALLY wacky. Like running out to the parking lot at work and urinating while standing on the bosses car. Can’t you just hear him later, “Wow, I did that? Sorry Boss, I must have had a real bad Low!”
At some level, hypoglycemia as the ability to let our unconscious thoughts come out. Kind of like being drunk and doing something embarrassing you don’t remember later. Has anyone here ever woke-up with paramedic surrounding your bed asking you what day it is? Maybe yours was running naked our the front door one night mumbling something about the ice-cream man coming? This can happen to anyone as it is really very easy to et too much insulin.
No one has to tell most people with diabetes that low blood sugar or hypoglycemia is one of the most common and potentially dangerous problems of diabetes. Mild hypoglycemia is annoying and embarrassing; severe episodes can lead to brain damage, seizure, coma, or, even death.
Although the famous 1993 DCCT study showed conclusively that reducing blood glucose levels also reduces long-term diabetes complications, it also found that people who keep their blood sugars close to the normal range have a three times greater chance of hypoglycemia. Some of the 27 centers involved in the DCCT were able to achieve nearly normal average blood sugar readings with very little hypoglycemia. However, a significant risk remains when tight control is attempted.
Hypoglycemia is dangerous because it impacts the brain or nerve center, which derives almost all of its energy from glucose. The brain depends on the bloodstream for a continuous supply of glucose because it can only store a few minutes’ worth of energy as glycogen. Any change in blood glucose levels can quickly and seriously affect thinking and coordination.
Hypoglycemia can usually be detected by the brain, but the brain relies heavily on warning signals generated by the central nervous system as the blood sugar drops. Signals like sweating and shaking are produced by the release of stress hormones in a process called glucose counter-regulation. This release starts the slow return of the blood sugar to the normal range. The liver, interestingly, is directly involved as well in sensing and correcting low blood sugars. Remember that some type 1s lose this response (the body’s own ability to raise BG’s) altogether over the years.
Non-diabetics can count on the body’s backup systems for raising a low blood sugar. In a research paper done by Dr. Philip Cryer at the Washington University School of Medicine, these recovery systems were outlined in non-diabetic volunteers. Physical responses that generate recovery are triggered at different glucose levels.
The first response, which occurs at around 83 mg/dl, is a reduction of insulin production, while the second, the release of epinephrine into the bloodstream, begins at 69 mg/dl, but plays a minor role unless the supply of glucagon becomes deficient. Glucagon release begins at 68 mg/dl, followed at 67 mg/dl by a reduced glucose uptake into the brain. And at 66 mg/dl, the body releases the growth hormone somatotropin, which tells the body to reduce its use of glucose (so this defense mechanism is trying to keep us form going too Low). Somatotropin also tells the body to increase the use of fats as fuel.
As the blood glucose level reaches 58 mg/dl, cortisol, a steroid that promotes the conversion of glycogen into glucose, is released to assist in raising the body’s glucose levels. For these test subjects, when the glucose level fell to 54 mg/dl, the body’s hypoglycemic symptoms started. At 49 mg/dl thinking becomes impaired, as now the brain is low on glucose too.
Long term type 1s who lack a good epinephrine and glucagon response, are 25 times more likely to experience severe hypoglycemia than those who respond normally.
Two types of symptoms are associated with hypoglycemia: neurogenic (body) symptoms, which originate in the nervous system, affect the body, and are usually noticed by the person with diabetes himself; and neuroglycopenic (mind) symptoms, which affect the mind. The latter are a direct result of glucose deprivation in the brain, and are frequently noticed by others but not by the person with diabetes.
In the controlled study of non-diabetics, the neurogenic symptoms occur at around 54 mg/dl and include shaking, pounding heart, nervousness, sweating, tingling, and hunger, while the neuroglycopenic symptoms which occur at 49 mg/dl are confusion, drowsiness, weakness, feeling too warm, difficulty speaking, impaired coordination, and odd behavior (and, of course, coma, seizures, and death).
Risk Factors for Hypoglycemia:
1-an excessive insulin in the blood (due to either high injected dosage or missed meals),
2-an increase in the use of insulin (as seen during exercise),
3-a decrease in glucose production (as occurs after drinking alcohol), or
4-an increase in insulin sensitivity (also seen during exercise).
5-a history of severe hypoglycemia,
6-having type 1 diabetes for over 9 to 12 years,
7-any lowering of HbA1c levels, and
8-an increase in your insulin dose.
9-Any hypoglycemia can impair the body’s detection of hypoglycemia for up to 3 days. This means glucose levels must go even lower to produce hypoglycemic symptoms and activate glucose counter-response after any hypoglycemia.
Hypoglycemia unawareness, the clinical condition in which people no longer experience the neurogenic symptoms of low blood sugars, affects many people with type I diabetes and a few with type 2. The glucose levels needed to trigger glucose counter-response are lower in people with hypoglycemia unawareness and the first symptoms they usually experience are neuroglycopenic, a sign of blood sugars of 49 mg/dl or less.
Recent studies indicate that avoiding hypoglycemia for a period of time as short as a few weeks may reverse hypoglycemia unawareness. (See the Uncomplicating Column in the March, 1994, issue of Diabetes Health.) People who suffer from hypoglycemia unawareness should monitor their blood sugar levels very closely. Hypoglycemia unawareness itself increases the risk for hypoglycemia by seven times.
Hypoglycemia is dangerous. As a complication of diabetes, it is perhaps the most easily treated, but can also be the most immediately dangerous. Awareness of the signs, symptoms, and risks of hypoglycemia, and diligent monitoring of blood sugars allows hypoglycemia to be controlled and even avoided. This can be vital, because like many things about diabetes, hypoglycemia is a self-perpetuating problem.
This article was refined from a review article called “Hypoglycemia” which appeared in the July, 1994 issue of Diabetes Care.
Please join me below in the Comment section! Share your experiences of hypo success, or tell us about your worst low, what happened and what you learned.
— Scott King, Editor-in-Chief, 34 years on insulin