What is hypoglycaemia?

Hypoglycaemia is when blood sugar falls below the normal range (less than 3.9 mmol/L or 70 mg/dL).

Types of hypoglycaemia

Mild hypoglycaemia

  • Causes discomfort
  • Resolves promptly with prompt ingestion of carbohydrates
  • Though named “mild”, it can still significantly impact quality of life

Severe hypoglycaemia

  • Causes impairment of cognitive function
  • Can lead to loss of consciousness
  • Can be life threatening1

Nocturnal hypoglycaemia

  • Occurs during sleep and is often asymptomatic
  • Repeated exposure can disrupt the body’s natural blood sugar regulation system, leading to serious clinical consequences

To align hypoglycaemia terminology in clinical trials and encourage appropriate responses in clinical practice, the IHSG has developed the following definitions:1

Level 1

A glucose alert value of 3.9 mmol/L (70 mg/dL) or less. This often doesn’t need to be reported routinely, depending on the purpose of the clinical study.

Level 2

A glucose alert value of <3.0 mmol/L (<54 mg/dL) is sufficiently low and indicates serious, clinically important hypoglycaemia.

Level 3

As defined by the ADA, severe hypoglycaemia indicates severe cognitive impairment requiring external assistance for recovery.

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Epidemiology

In people with type 1 diabetes (T1D), for which insulin treatment is assumed, the prevalence of severe hypoglycaemia increases with the duration of T1D.

Annual prevalence of hypoglycaemia based on T1D duration
People with T1D for less than 5 years
20% develop hypoglycaemia
People with T1D for 5 years or more
More than 40% develop hypoglycaemia
Annual prevalence of hypoglycaemia based on T1D duration
People with T1D for less than 5 years Arrow cutout 20% develop hypoglycaemia
People with T1D for 5 years or more Arrow cutout More than 40% develop hypoglycaemia

In people with type 2 diabetes (T2D), both duration and medical treatment influence the risk. The annual risk of severe hypoglycaemia is significant for people with T2D on sulfonylureas (SUs) and on insulin, especially if on insulin for over 5 years (>20% risk). Non-severe hypoglycaemia, which adults can self-treat, is more common than severe hypoglycaemia, but poses far less risk to health and life.

chart: annualized incidence of hypoglycaemia

References

  • 1
    International Hypoglycaemia Study Group. Glucose Concentrations of Less Than 3.0 mmol/L (54 mg/dL) Should Be Reported in Clinical Trials: A Joint Position Statement of the American Diabetes Association and the European Association for the Study of Diabetes Diabetes Care 2017;40:155–157.
  • 2
    Aronson R et al. The Canadian Hypoglycemia Assessment Tool Program: Insights Into Rates and Implications of Hypoglycemia From an Observational Study. 2018;42:11–17.
  • 3
    Cryer PE. Elimination of hypoglycemia from the lives of people affected by diabetes. Diabetes 2011;60:24.