List the causes of hyperglycaemia in the intensive care patient  population, and outline your management of hyperglycaemia.

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College Answer

A list of potential  causes should include: diabetes mellitus (previously known or not known, type I
or II, on diet, oral agents, insulin or combination), secondary causes of diabetes (e.g. pancreatitis, haemochromatosis, Cushing’s syndrome, acromegaly), insulin resistance (e.g. sepsis, systemic inflammatory response/stress response [including multiple trauma], beta-agonists [endogenous or exogenous], exogenous corticosteroids), carbohydrate load (e.g. feeding enteral/parenteral, peritoneal dialysis).

The outline  of management should include: control of factors worsening response to insulin (sepsis, drugs, stress response), control glucose within acceptable range (minimise metabolic and immune effects), recommence oral agents or use insulin (dependent on severity).   Principles of glucose control in diabetics include always administering some insulin, administer some glucose, measure glucose frequently, expect sudden  changes, and  avoid hypoglycaemia. Tight  glucose control is still controversial in the critically ill patients. Recent studies suggest tight glucose control using insulin infusions if necessary may dramatically reduce mortality after myocardial infarction (in diabetic patients: DIGAMI. BMJ. 1997 May 24;314(7093):1512-5), and in the surgical intensive care (N Engl J Med 2001;345:1359-67) but a more recent study by same group in medical ICU patients provides less striking results (N Engl J Med 2006;354:449-61), and the risk of hypoglycemia appears significant (Am J Respir Crit Care Med 2006;173:367-9).

Discussion

The below-linked table of causes can be found in the chapter on stress-induced hyperglycaemia

Causes of Hyperglycaemia in the ICU

Insulin resistance

  • NIDDM
  • Stress response
  • Corticosteroid therapy
  • Cushings disease

Inadequate insulin levels

  • Under-supplemented
  • Stress response
  • Pancreatitis
  • Haemochromatosis
  • Insulin antibodies

Excessive endogenous glucose release

  • Catecholamine infusion
  • Stress response
  • Glucagon administration

Excessive exogenous glucose supplements

  • TPN with 50% dextrose
  • Inappropriately sugary IV fluids
  • Overfeeding with enteric nutrition
  • Glucose-containing peritoneal dialysis fluid

As for the glucose control strategy: this is better discussed in the chapter on glucose control among the critically ill, but here is the basic breakdown of the current strategies, and the trials that spawned them. The college answer given here is written prior to 2009, and therefore shares the delusional attachment to tight glycaemic control which characterises the tumultuous first decade for the 21st century.

These days, with the benefit of the 2009 NICE-SUGAR trial and its 2012 post-hoc analysis, we know that keeping BSL under 10mmol/L is the ideal strategy, as it protects the patients from the evils of hyperglycaemia, while preventing the increase in mortality which is associated with unbearably tight glycaemic controls.

In summary,

  • Keep the BSL between 5 and 8mmol/L, and definitely keep it under 10mmol/L

References

References

Finfer, Simon, et al. "Hypoglycemia and risk of death in critically ill patients."The New England journal of medicine 367.12 (2012): 1108-1118.

 

Finfer, Simon, et al. "Intensive versus conventional glucose control in critically ill patients." N Engl J Med 360.13 (2009): 1283-1297.

 

Griesdale, Donald EG, et al. "Intensive insulin therapy and mortality among critically ill patients: a meta-analysis including NICE-SUGAR study data."Canadian Medical Association Journal 180.8 (2009): 821-827.