Question 15.3 from the first paper of 2008, where the candidates were invited to list 4 likely causes of hypoglycaemia for a Type 1 diabetic.

The causes of hypoglycaemia are protean. Here are just a few:

Causes of Hypoglycaemia

Drugs

  • Insulin (duh)
  • Glucagon
  • Indomethacin
  • Lithium
  • ACE-inhibitors
  • β-blockers
  • Alcohol
  • Sulfonylurea drugs
  • Perhexiline
  • THAM

Illness

  • Starvation
  • Hepatic failure
  • Cardiac failure
  • Renal failure
  • Sepsis
  • Adrenal insufficiency
  • Insulinoma
  • Antibodies to insulin receptor
  • Hypothyroidism
  • Massive burden of bulky maligancy
  • Islet cell hyperplasia

Pragmatically speaking, it is very rarely anything quite as exciting as an insulinoma. A study of patients admitted with hypoglycaemia has identified several common causes, listed below and ordered from most to least common:

  • Inadequate intake of carbohydrate (28%)
  • Ingestion of alcohol (19%)
  • Deliberate overdose of insulin (13%)
  • Accidental overdose of insulin (6%)
  • Strenuous exercise (7%)

Broadly, the causes of hypoglycaemia in the known diabetic are:

  • No enough glucose
    • Decreased intake (forgot to eat!)
    • Decreased gluconeogenesis (alcohol)
    • Increased use (exercise)
  • Too much insulin
    • Increased administration (trying to kill yourself)
    • Increased sensitivity (hypoglycaemic agents, weight loss)
    • Decreased clearance (renal failure)

The consequences of hypoglycaemia are largely related to its effect on the CNS. In his review article, Gale (1985) insists that a distinction be made between hypoglycaemia (which is a biochemical description of a low blood sugar concentration) and neuroglycopenia (the clinical syndrome which results from it).

References

UpToDate has a nice article on this for the paying customer.

Cryer, Philip E., Stephen N. Davis, and Harry Shamoon. "Hypoglycemia in diabetes." Diabetes care 26.6 (2003): 1902-1912.

Hart, S. P., and B. M. Frier. "Causes, management and morbidity of acute hypoglycaemia in adults requiring hospital admission." Qjm 91.7 (1998): 505-510.

Gale, E. "Causes of hypoglycaemia." British journal of hospital medicine 33.3 (1985): 159-162.

Gama, R., J. D. Teale, and V. Marks. "Best Practice No 173 Clinical and laboratory investigation of adult spontaneous hypoglycaemia." Journal of clinical pathology 56.9 (2003): 641-646.