First, many people speak of hypoglycemia but are referring to the symptoms - Somebody
(whether diabetic or not) might get the shakes, etc., and state that they're "hypoglycemic" which, medically, they may or may-not be.
Hypoglycemia itself simply means low blood sugar, and is not necessarily life-threatening.
There are many thresholds, depending on who you listen to. The general medical definition is simply 'below 3.9 mmol/L or 70 mg/dl', however, this level of hypoglycemia is not life-threatening
(unless it's continuing to drop, unabated - but then a 68 isn't the issue, it's when it gets into the 30's and 20's it becomes an issue...)
When medical professionals
(I was one for several years before moving into another field) speak of hypoglycemia as something dangerous, they're referring to a severe, life-threatening medical condition.
Severe hypoglycemia occurs when:
- The patient is under the threshold the medical establishment in the area has set, and;
- The patient's BG levels are not self-correcting - they are continuing to drop.
The 'threshold'
(whether 70mg/dl, 55mg/dl, etc.) is set according to the emergency medical governing bodies in the area. This may be as small as a per-hospital basis - or in my case
(in Alberta, Canada) it's a provincially-regulated medical definition.
Regarding Symptoms:
For some reason it would appear that Type 2 diabetics feel symptoms more commonly than Type 1 - I'm just using anecdotal evidence and my own experience for that. On this forum Adjitater has mentioned he often doesn't feel symptoms we associate with hypoglycemia. In one small town I worked in we often had a patient - a Type 1 lady - that required emergency services because her hypoglycemia would come on so fast, she'd hit the floor while trying to make/get a snack to eat.
Hypoglycemic symptoms can be felt
(by people who feel them... not everyone does...) at any glucose level, including WELL-ABOVE the 70mg/dl mark - but it depends on the person. This most often happens in those whose blood sugars are normally quite high; such as the newly-diagnosed, somebody starting insulin or medication therapy, etc. Most of us Type 2's have experienced it as our blood sugars started to 'normalize'.
Using my case as an example - I had fastings in the 14.8 mmol/L (267 mg/dl) mark and an A1c of 12.1% ... this would mean my 'normal' blood sugar (for my diabetic condition) was around 16.6 mmol/L (300 mg/dl). When I first reduced it to even the 9.0 mmol/L (162 mg/dl) mark, I
felt hypoglycemic, though
medically I was not.
(You could say my body was hypoglycemic for it's normal condition, however.) As my sugars started to stabilize and my A1c reached 6.0%, I no longer feel hypoglycemic symptoms until around the 3.5 mmol/L (63 mg/dl) mark.
Dangerous/Life-threatening?
Whether hypoglycemia is a dangerous condition, or simply a condition depends on what our system is doing.
In my case, I used to have no issues with hypoglycemia. I would drop below 4.0 mmol/L (72 mg/dl) and my liver would dump glucose into my system. So even if I became hypoglycemic
(according to some thresholds) my body didn't stay there. This is the case for many, if not most, of us.
(Our body is normally self-correcting. It does it's best to remain in homeostasis.)
However, for those going extremely low-carb, for someone with impaired glycogen reserves, or for someone doing more activity than they have the ability to fuel
(Although exercise is mostly fueled by ATP which can come from both glucose or fat, we will always burn glucose if it's available - which comes from blood glucose, carbohydrate being digested into blood glucose, glycogen stores and protein that can be converted via gluconeogenesis) or anyone using insulin or some of the more aggressive oral glucose-lowering meds - severe hypoglycemia, because either the liver has nothing to 'dump', or the insulin/medication is counteracting it too rapidly, may be a real issue - depending on their bodies, their medications, etc. That's the case for me now, and I need to be cautious. Although I usually have a liver dump that fixes lows - I don't always have what the liver needs to do this, and as such sometimes I can only fix a hypo with fast-acting sugars.
To Sum it up:
So again, hypoglycemia has different definitions depending on who you talk to:
- Some may refer to it but mean the feeling of symptoms often associated with the condition (although this is incorrect, it would be more accurate to define this as hypoglycemic symptoms);
- Some refer to it as simply being under 3.9 mmol/L (70 mg/dl) or any other threshold they believe qualifies (which may or may-not correct itself);
- In emergency medicine, and when any medical professional speaks of it as something they have concern for, they mean the condition of low-blood sugar (under the threshold defined in their area) that is not being self-corrected. (Generally, if a person is still conscious, it is often corrected orally - during loss-of-consciousness or in cases of severe errors in insulin dosage, it may require IV injection of glucose to correct.)
Just my 2c worth.