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Hypoglycemia

Diabetes Canada updated the chapter on Hypoglycemia in Adults in 2023. The complete chapter is available here.
In people with diabetes treated with insulin or insulin secretagogues, hypoglycemia is a major limiting factor in trying to achieve glycemic targets. It affects people in several ways, including:

  • Risk of Level 3 hypoglycemia (see below for definitions) may necessitate higher glucose target levels.
  • The number and severity of hypoglycemia can affect quality of life.
  • Fear of hypoglycemia may lead people to choose to target higher glucose levels.

Definitions

In teaching patients about hypoglycemia, and in patient resources, we use <4.0 mmol/L as the level used as a definition. International guidelines are based on a cut-off of 70 mg/dL, which equates to 3.9 mmol/L.

Initial symptoms are usually adrenergic (trembling, palpitations, sweating, anxiety, hunger, nausea, tingling), followed by neuroglycopenic (difficulty concentrating, confusion, weakness, drowsiness, vision changes, slurred speech, headache, dizziness). In people with impaired counter-regulatory responses (impaired awareness), the first symptoms of hypoglycemia may be neuroglycopenic.

The severity of hypoglycemia is defined by symptoms and risks, not by the glucose level.

  • Level 1: Glucose below 3.9 mmol/L; Adrenergic (autonomic) symptoms; no neuroglycopenic symptoms or changes to mental status
  • Level 2: Glucose below 3.9 mmol/L (often below 3.0); neuroglycopenic symptoms; +/- agrenergic (autonomic) symptoms; no significant changes to mental status
  • Level 3 (formerly called “severe” hypoglycemia): Glucose below 3.9 mmol/L; neuroglycopenic symptoms resulting in significant changes to mental/physical status; requires assistance to treat

Be discerning in your use of the terms Level 3 or severe hypoglycemia. These terms are limited to situations in which the person is unable to adequately and safely self-treat hypoglycemia and requires outside help, such as a family member, friend or EMS. Using either term in a medical chart note to an MD for situations that do not meet the above definition, can mistakenly lead to a temporary suspension of driver’s licenses. Alberta requires periodic physicals for those driving while on insulin. Usually, there is a question for physicians to answer regarding the history of severe hypoglycemia in the past number of months.

 

Preventing Hypoglycemia

Utilizing strategies to prevent hypoglycemia is preferable to treating it once it occurs. Possible strategies include:

 

Treating Lows

Level 1 or Level 2 hypoglycemia:

  • 15 g of quickly-absorbed carbohydrate (See handouts here).
  • Wait 15 minutes and re-check glucose level. If still below 3.9 mmol/L, treat again.
  • Repeat until glucose is above 3.9
  • If the next meal is > 1 h away, have a snack including 15 g carb and a protein source.

Level 3 hypoglycemia (conscious and able to swallow):

  • 20 g of quickly-absorbed carbohydrate (e.g. 250 mL juice or regular pop, OR 25 mL (5 tsp) sugar dissolved in water OR 20 mL (4 tsp) honey).
  • Wait 15 minutes and re-check glucose level. If still below 3.9 mmol/L, treat again.
  • Repeat until glucose is above 3.9
  • If the next meal is > 1 h away, have a snack including 15 g carb and a protein source.

Level 3 hypoglycemia (unconscious):

Additional considerations:

  • Sometimes smaller treatments are needed: In Automated Insulin Deliver (AID) pumps the treatment of hypoglycemia may require less than 15 g of carbohydrate (the systems toggles insulin delivery down in advance).
  • Sometimes larger initial treatments are needed: Although over-treating is discouraged, some episodes of hypoglycemia may require an initial treatment of more than the recommended 15 g carbohydrate. The more of the factors below that are present, the higher the initial grams of carbohydrate suggested for treatment:
    • The low is during peak action time of insulin
    • The low is before, during or after physical activity
    • The reading is < 3 mmol or more than 1-2 mmol rise is needed to reach target
    • The target blood glucose target is higher than the usual 4 - 7
    • The clearance of diabetes medication is slowed (advanced renal disease)
    • Other circumstances you judge may affect safety of client

      Example: A 75 year old frail man, A1c target 8.5% with hypoglycemia unawareness and previous severe hypoglycemia. NPH bid and rapid TID.  Glucose reading is 3.2 mmol/L at 1:30 pm, which is 1 hr pc lunch. After the appointment the client is expected to walk from the office, down 3 long hallways to get his taxi and then into his lodge. In this situation, the client was initially treated with 45 g rapid carbohydrate, followed by 15 g of carbohydrate from cookies once he was above 5 mmol/L. On arrival at the lodge, his blood sugar was 5.3 mmol/L.
  • Treating pre-meal hypoglycemia: Patients might require reminding to treat hypoglycemic events that occur before meals. These treatments may be wrongfully omitted resulting in subsequent repeated hypoglycemia.

 

Impaired Awareness of Hypoglycemia (IAH)

IAH (previously called “Hypoglycemic unawareness”) is characterized by the loss of early adrenergic (autonomic) warning symptoms of hypoglycemia (hunger, sweating, tremor, palpitations, etc.). As a result, the person affected may not be aware of an impending low blood glucose until they are experiencing central nervous system dysfunction (neuroglycopenia). Neuroglycopenia may present with symptoms such as confusion, lethargy, combativeness or stupor resulting in the client being unable to respond to and treat the hypoglycemia appropriately. Thus, the person is at risk for Level 3 hypoglycemia that may result in seizures, coma and death.

  • Each episode of hypoglycemia may decrease awareness of the next antecedent episode by causing both defective glucose counter-regulation (blunted epinephrine response to hypoglycemia) and reduced sympathoadrenal response to subsequent hypoglycemia. Prior and frequently recurrent hypoglycemia is associated with IAH.
  • Autonomic neuropathy is associated with a higher risk for this condition but is not required for IAH to be present.
  • Strong predictors of IAH are low A1c, history of frequent hypoglycemic episodes, aiming for very tight glycemic control, widely fluctuating readings including many lows, and frequent nocturnal hypoglycemia – of which many episodes clients may not be aware. Seizures are more likely to occur overnight.
  • IAH is potentially reversible by strictly avoiding hypoglycemia for as little as 2 weeks, up to 3 months.

 

Glucagon

Glucagon is one of the counter-regulatory hormones released from the alpha cells in the Islets of Langerhans in the pancreas. It signals muscle and liver cells to break down glycogen stores into “ready-to-use” glucose (glycogenolysis).
  • As a treatment for severe hypoglycemia, glucagon is available in an injectable form and as a nasal powder. See this section of our Complete Medication Table (Glucagon heading) to see company literature or videos about glucagon. Patient information on the use of glucagon is available on MyHealth Alberta: 
  • Injectable glucagon exists in a powdered form and must be mixed with the diluting liquid provided in the package.
  • Glucagon kits are expensive and expire. Clients are encouraged to check expiry dates on package before leaving the pharmacy to make sure it is viable for at least 6-12 months.
  • Those with type 1 diabetes, especially those with impaired awareness of hypoglycemia, are advised to keep glucagon available for friends or significant others to use on them should they be unable to self-treat a low glucose.  Glucagon should be carried when away from home when on vacation or if some distance from a health care facility, e.g. hiking in the mountains.