Causes and Risk Factors

Hypoglycaemia in diabetes typically occurs as a result of medical treatment, particularly with insulin, sulfonylureas (SUs) or glinides. Certain patient characteristics and disease factors put people at higher risk:

Risk factors for hypoglycaemia1-4

Type 1 diabetes Type 2 diabetes
(on insulin or SUs)
  • History of severe episodes
  • HbA1C < 6.5%* (except in youth)
  • High glucose variability (in older adults)
  • Long duration of diabetes
  • Renal impairment
  • Impaired awareness of hypoglycaemia
  • Advanced age
  • Advancing age
  • Cognitive impairment
  • Depression
  • Aggressive treatment of glycaemia
  • Impaired awareness of hypoglycaemia
  • Duration of insulin therapy
  • Renal impairment and other comorbidities

In addition, specific behaviours and insulin-related factors may increase the risk of nocturnal hypoglycaemia:5,6

  • Missed meal, alcohol consumption
  • Unplanned physical activity, especially strenuous
  • Failure to check blood glucose at bedtime
  • Dose of basal insulin too high
  • Too much rapid-acting insulin to correct high glucose, particularly at bedtime, or to cover bedtime snacks
  • Premix or short-acting insulin before dinner
  • NPH insulin (isophane) in the evening


  1. UK Hypoglycaemia Study Group. Risk of hypoglycaemia in types 1 and 2 diabetes: effects of treatment modalities and their duration. Diabetologia 2007;50:1140.
  2. International Hypoglycaemia Study Group. Minimizing hypoglycemia in diabetes. Diabetes Care 2015;38:1583.
  3. Inzucchi SE et al. Management of hyperglycemia in Type 2 diabetes, 2015: A patient-centered approach. Diabetes Care 2015;38:
  4. Weinstock RS et al. Risk factors associated with severe hypoglycemia in older adults ith Type 1 diabetes. Diabetes Care 2016 Apr;39:603.
  5. Lipska KJ et al. HbA1c and risk of severe hypoglycemia in Type 2 diabetes. Diabetes Care 2013;36:3535.
  6. Brunton SA. Nocturnal hypoglycemia: Answering the challenge with long-acting insulin analogs. MedGenMed 2007;9:38.