ICN Vic - glucose control in diabetics
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Transcript of ICN Vic - glucose control in diabetics
RINALDO BELLOMOINTENSIVE CARE UNIT
AUSTIN HOSPITAL,MELBOURNE, AUSTRALIA
Defining the correct glucose target in critically ill diabetic
patients?(why intensivists are becoming diabetologists)
Glucose control in ICU and post-op
Hyperglycemia in ICU patients is almost universalGlycaemic control in ICU and post-operatively is an
article of faith. The reasons we apply it are: We are intensivists and we are secretly sworn
upon a sacred oath to normalize all physiologyPhysiological reasoning (hyperglycemia induces
glycosuria. Glycosuria may cause dehydration which may be bad. So we should avoid hyperglycemia)
Why treat hyperglycemia in ICU II
2. Association with specific risk (some diabetics with poor glucose control develop diabetic keotacidosis or hyperomolar non-ketotic diabetic coma. So we should avoid hyperglycemia )
3. Association with general risk (hyperlycemia in ICU is independently associated with mortality and maybe even with infection [which came first hyperglycemia or infection?]. So we should avoid hyperglycemia)
Could we be wrong?
Impossible!
ITT: the new black!
Serious problems
Single centreProtagonist involved in direct patient careOutcome to 28 days onlyGlycaemic control data only in am bloodsP level low (0.04)Most of the effect in cardiac surgery patients
but with controls carrying a mortality of 5.1%!
High mortality in other controls for a given mean APACHE score
The big trial
IIT increases mortality
The problems with applying belief systems to everyone
As expected
Glycemia in diabetics is different
Hypoglycemia is similar
Despite higher overall glucose levels diabetics develop hypoglycaemia three times as often (which must mostly be iatrogenic)
• High rate of hypoglycemia and 3% excess mortality in intensive control group
• Cardiovascular cause of death more common in the intensive control group
• Hypo independently associated with increased mortality
• Association strongest among patients with distributive shock
hypoglycemia per se may be harmful
Chemoreceptors incarotid glomus
Cardiac baroreceptor sensitivity
Heart rate variability
Sympathetic outflow
Cardiovascular instability
Hypoglycemia
Previous hypoglycaemia increases hypothalamic activation during subsequent hypoglycaemia (which inhibits sympathetic activation – the so-called habituation response to stress)
Hypoglycemia is ”silent” in ICUWhich makes it particularly bad
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Bloo
d G
luco
se L
evel
(m
mol
/L)
3.9
• Activation of hormonal counterregulation– Adrenaline– Noradrenaline– Cortisol– Growth hormone– Glucagon
• Neuroglycopenic symptoms– Confusion– Weakness– Drowsiness– etc…
NoDiabetes
invisible
But things may well be even trickier in diabetics! The concept of relative hypoglycemia
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Bloo
d G
luco
se L
evel
(m
mol
/L)
NoDiabetes
30%
30%
Diabetes
• Evidence from ’clamp studies’
• 30% drop from baseline triggers hormonal/neuroglycopenic responses (relative hypoglycemia)
• Hypoglycemia counter-regulation can occur within a normal blood glucose range in patients with chronic poor glucose control
The adverse effects of hypoglycemia may happen at a normal glucose level in diabetics
Do we have reasons to believe this is true?
Questions
How does chronic glycaemic control influence the relationship between acute glycaemia and outcome
What is hypoglycaemia in a diabetic patient?
Is it the same as in a non-diabetic?Is there a different response?If so what does it mean?
Conventionalrange
10-14 mmol/l
Ketones
MIMIC database (Harvard)Mortality and relative hypoglycemia (>30% fall b/w 2 consecutive blood gases)
Frequency of relative hypoglycemia and risk of death
Where to from here?Evidence that glucose control in ICU matters (NICE-
SUGAR trial)Evidence that hypoglycaemia is badEvidence that relative hypoglycaemia existsEvidence that it may also be badEvidence that diabetics (esp. bad ones) are different
and at particular risk of relative and absolute hypoglycaemia
Evidence we can assess chronic glycaemic control on admission by HbA1c
Evidence we can decrease relative hypoglycaemia with liberal glycaemic control in diabetics
RCTs applied for and likely to start soon