Causes of Hypoglycemia

If you have diabetes, you are at risk of developing other diseases and disorders.  A potential complication of diabetes treatment is hypoglycemia. In fact, hypoglycemia is very normal and not at all unexpected for any individual who takes insulin or any form of pancreatic stimulant. Some examples of medications that can cause hypoglycemia are Glipizide, glyburide, and Prandin to name a few.

What is Hypoglycemia?

Hypoglycemia is the term used to describe a blood sugar level that is significantly lower than it should be. It falls below the normal range which is stated as being between 70-130 mg/dl[2]

There are 3 levels of severity associated with hypoglycemia. Each higher level increases the risk for further complications.

  • Mild: The blood glucose is at approximately 70 mg/dl. Mild hypoglycemia is revealed by testing prior to the onset of symptoms. This level is readily treated by oral carbohydrates.
  • Moderate: The blood glucose is approximately 55 mg/dl. There are symptoms and signs but the patient does not recognize the need to make a response. The patient should be given glucose in sufficient quantities to restore it to the right level. Repeated testing must ensure it reaches and maintains this level.
  • Severe: The blood glucose is 40 mg/dl or below. The individual may possibly be unconscious. The individual requires acute care, perhaps an injection of glucagon.

What are the Causes of Hypoglycemia?

Hypoglycemia in both type 1 diabetes and advanced type 2 diabetes is the result of the interaction between treatment insulin excess and compromised defenses – physiological and behavioral – leading to falling blood glucose levels. It all revolves around this failure of treatment or biological systems that results in the brain, which receives its glucose passively, receiving too little to function properly. The brain cells, deprived of a source of glucose, suffer. The result is confusion followed by coma and possibly death.

While there is a specific explanation for the event, there are various possible explanations for a hypoglycemia developing:

a)   Too much insulin – The individual gives him or herself too large an injection of insulin

b)   Too little food – There was not enough of an intake of food, specifically carbohydrates, to balance the insulin

c)   Too much exercise – Since exercise causes muscles to use glucose, leaving less available in your blood for your brain. The amount of injected insulin can be adjusted to compensate for this change in available glucose to prevent hypoglycemia.

d)   Alcohol without food – Alcohol and insulin are not a good combination. Alcohol inhibits the liver from releasing glucose.

e)   Wrong insulin prior to bedtime – If you use rapid acting instead of slow acting insulin before going to bed, hypoglycemia may result

f)    Abnormally rapid absorption of insulin – If you use a new site, the insulin might release more quickly than previously used sites.

g)   Poor timing of food with insulin – If the insulin is injected too soon before a meal, you may have low blood glucose before you get a chance to eat

h)   Slow glucose absorption from GI tract – Certain chronic conditions e.g. celiac disease, and even some acute conditions, may impede the uptake of glucose

i)     Hormones are inadequate to raise the blood sugar – In the dearth of glucagon the reaction to low blood glucose is severely reduced

j)   Mental spill-over from previous hypoglycemia – The past incidents of hypoglycemia may have an effect on the ability to be aware of further incidents. This is referred to as hypoglycemia unawareness

k)     Use of beta blockers – These may reduce the level at which hypoglycemic symptoms occur initiating reduced awareness.

Symptoms and Signs of Hypoglycemia

There are several indications you are suffering from hypoglycemia. They are usually divided into 2 separate categories: adrenergic or those caused by the response to hormones, and neuroglycopenic or those caused as a result of a failure of the brain cells to be adequately nourished with glucose which flows passively into the cells. If there’s low glucose, then there’s low flow.[3]

  • Neurogenic symptoms – These are automatic responses. They are divided into cholinergic neurogenic and adrenergic neurogenic symptoms. The latter indicates a protective response that is due to the body’s attempt to raise blood glucose levels before the brain suffers.  As such, the adrenergic response is motivated at a slightly higher blood sugar level than that which triggers the neuroglycopenic response.

Symptoms of an adrenergic response include: anxiety, irritability, numbness of the lips fingers and toes, palpitations, rapid heartbeat, a sensation of hunger, sweating and whiteness or pallor of the skin. Symptoms of a cholinergic neurogenic response consist of sweating, hunger, and paresthesias (numbness).

  • Neuroglycopenic symptoms and signs are all liable to be confused with alcoholic intoxication: confusion, trouble concentrating; convulsions; dizziness; fatigue; feeling of warmth; headache; loss of concentration; poor color vision; reduced consciousness or coma; slurred speech; trouble hearing; blurred vision.

Hypoglycemic Unawareness

Reducing the ability to take action when an individual becomes hypoglycemic is an effect called “hypoglycemic unawareness.” It occurs in 25% of those individuals who have T1D. It is also common in people with T2D. It is the result of several factors including:

  • Lengthy period of having diabetes
  • Extremely tight control of the blood glucose
  • Frequent instances of hypoglycemia
  • Nerve damage

Individuals who have hypoglycemic unawareness have adapted to hypoglycemia. As a result, it takes blood glucose at lower levels to trigger a release of epinephrine and set off warning signals. [4]

Frequency of hypoglycemic bouts

As Cryer (2008)[5] points out, hyperglycemia is simply a “fact of life” for many individuals who have type 1 diabetes (T1D). The average person with T1D will:

  • Have any number of episodes of asymptomatic hypoglycemia
  • Have 2 episodes of symptomatic hypoglycemia a week
  • Have 1 or more episodes of what is termed severe and disabling hypoglycemia every year. These are often accompanied by a seizure or, worse still, a coma.

Severe hypoglycemia is not as common in type 2 diabetes because they are generally less dependent on insulin injections to control their diabetes than T1D patients. However, milder occurrences are very common.


Hypoglycemia is a serious complication of diabetes. It can result in severe consequences if not addressed in time. These can include coma and death. It is important to understand and recognize the signs of hyperglycemia. It is also important to know when you are subject to hyperglycemic unawareness.


[1] Meltzer, SJ; and Belton, AB (2009). Diabetes in Adults. Toronto: Key Porter Books.

[2] Marcovitch, H (2006). Black’s Medical Dictionary 41st edition. Lantham, Maryland: Scarecrow Press.

[3] Cryer, PE (2006). “Hypoglycemia in Diabetes: Pathophysiological Mechanisms and Diurnal Variation.” Progress in Brain Research, 153: 361-365.

[4] Warshaw, HS; and Pape, J (2009). Real-Life Guide To Diabetes. Alexandria, VA: ADA.

[5] Cryer, PE (2008). “The Barrier of Hypoglycemia in Diabetes.” Diabetes, 57 (12): 3169-3176.

[6] This article was originally published July 12, 2012 and last revision and update of it was 9/10/2015.