Diabetes

Question 1

:) What’s HbA1c?

Answer 1

Test of the average amount of glucose bound to Hb over the past 3/12 (because this is typically how long a rbc lasts)- an idea of longer-term glycemic control

Question 2

:) What’s the R-R ratio?

Answer 2

ratio of the longest R-R interval during brady (phase 4) & shortest R-R interval during the tachycardia (phase 3), normal >1.21, abn <1.10

Question 3

:) What’s the management for a BGL <4 & pt NBM? if IV or no IV access?

Answer 3

15g (30mL of 50% glucose as slow IV push) every 15 mins until BGL >4. if no IV access, 1mg glucagon IM (1 dose only)

Question 4

:) What are the concerns in a patient with DM on insulin being on a pm list?

Answer 4

hypoglycaemia, DKA, postoperative medication recommencement/monitoring, micro/macrovascular complications (kidneys, heart, brain) & autonomic neuropathy

Question 5

:) Is UTI a side effect of SGLT2 inhibitors?

Answer 5

yes- usually mild

Question 6

:) What’s the WHO diagnostic criteria for diabetes?

Answer 6

diabetes symptoms (polyuria, polydipsia, unexplained weight loss) PLUS:

• venous HbA1c >= 6.5% (HbA1c <6.5% doesn’t exclude diabetes- readings may be confounded)
• random venous BGL >= 11.1mmol/L OR
• fasting BGL >= 7 mmol/L OR
• 2-hour plasma BGL >=11.1mmol/L after OGTT with 75g glucose
• if asymptomatic can’t diagnose based on one reading, require confirmatory plasma venous reading another day

Question 7

:) What factors may confound HbA1c?

Answer 7

abnormal erythropoiesis, increased rbc turnover, haemoglobinopathies

Question 8

:) What’s diagnostic criteria for GDM?

Answer 8

fasting BGL >=5.6mmol/L OR

2 hour BGL >=7.8mmol/L after OGTT

Question 9

:) What’s the recommendation from the 2011 NHS DM guideline for elective surgery HbA1c target?

Answer 9

<8.5% if possible

Question 10

:) Aside from the goal HbA1c <8.5% prior to elective surgery, what are other recommendations from the 2011 NHS DM guideline?

Answer 10

good glycemic control on day of surgery
appropriate pre-operative investigations (Ax co-morbidities, EUC + ECG)
establish clear periop plan re: glycemic control
schedule surgery at beginning of day to minimise disruption to usual glycemic control

Question 11

:) What are the preoperative instructions for basal insulin?

Answer 11

If T2DM with once-daily insulin, may continue basal insulin day before surgery it as long as it’s been adjusted to allow a safe morning glucose level.

If the pts insulin results in low-normal mane BGLs, give 80% dose the day before surgery. If mane dosing, check BGL (even if on infusion)

If BD dosing, give usual evening dose & half-dose morning of surgery (not if on infusion)

If pt has basal & prandial insulin, they omit prandial insulin once fasting begins.
if basal insulin is in the morning, give 1/2-2/3 TOTAL (basal &prandial) morning dose basal insulin to prevent ketosis during the procedure

If pt has a continuous insulin infusion pump, can continue it @ their usual basal rate assuming safe for the surgery & they’ll be alert enough to use postop. If prefers or must discontinue it @ home, give basal insulin 2-3hrs prior to pump discontinuation

Question 12

*should submit insulin pumps be used intra-operatively?

Answer 12

Not for major surgery as variable haemodynamics may vary subset absorption; ideally transition from pump to insulin/dextrose infusion

Question 13

*what are indications for insulin/dextrose infusions?

Answer 13

prolonged fasting (>1 meal missed)
type 1 DM
poorly controlled HbA1c (>=8.5%)
most DM patients who require emergency surgery

Question 14

Diabetes: 10 key issues

Answer 14

First on the list
risks of hypoglycaemia and DKA
glycaemic control & risk stratification
micro, macro & autonomic neuropathy
medication plan
ENDOCRINE involvement
aspiration risk: adequate fasting time, RSI
low threshold for IAL & 5-lead ecg (CV risk)
ANS neuropathy issues (vasopressors, temperature regulation)
PONV prophylaxis- promote early postop PO intake, OHGAs, endocrine input if prolonged fasting
BSL monitoring

Question 15

What are some of the manifestations of diabetic autonomic neuropathy?

Answer 15

Hx:
gastropareisis: GORD, dysphagia, constipation?
CVS: postural hypotension, syncope/pre-syncope, resting tachycardia? fixed HR (loss of R-R variation & long QT), painless myocardial ischaemia
GU: atonic bladder
sexual: erectile dysfunction
cold peripheries, unable to vasoconstrict to conserve heat. Sudomotor dysfunction (lack of sweating in glove/sock distribution)
pupillary abnormalities: loss of accommodation & other pupillary responses

examination:
palpate peripheries
postural BP drop >20mmHg systolic / >10mmHg diastolic

investigations:
R-R interval to valsalva: normal >1.21, abnormal is <1.10
checking HbA1c may give an indication re: longer-term glycemic control & likelihood of end-organ effects

Question 16

For which pts avoid dexamethasone?

Answer 16

T1DM or insulin-dependent T2DM

Question 17

What’s sudomotor dysfunction?

Answer 17

a common feature of diabetic autonomic neuropathy. It typically manifests first as anhidrosis of the extremities in a stocking-glove distribution, conforming to the length dependency of the neuropathy. Progresses to involve the upper aspects of the limbs, the anterior abdomen, and the top of the head and may ultimately result in global anhidrosis. Hyperhidrosis of the trunk may be seen early in the disease as a compensatory phenomenon.

Question 18

What’s autonomic neuropathy, what are some causes & factors increasing risk?

Answer 18

Autonomic neuropathy = multisystem disorder due to damage of ANS nerves
Causes = DM, Parkinson, MSA, idiopathic, amyloidosis
Increased risk of autonomic neuropathy – increased age, DM > 10y, IHD, beta-blockade

Question 19

What are the MAIN perioperative concerns for an insulin-dependent diabetic?

Answer 19

hypoglycaemia
DKA
Diabetic complications (eg. microvascular disease, microvascular disease, autonomic neuropathy)
BSL/medication management

Question 20

Principles for GA of a pt with diabetes?

Answer 20

first on list, periop medication plan
BGL monitoring +/- ketones pre-, intra- & postop
RSI with cricoid (slow gastric emptying)
limit myocardial O2 demand & ensure supply with adequate preload & MAP
low threshold for pre-op art line, 5-lead ecg & vasopressor running from outset (CV & autonomic neuropathy risk)
euvolaemia
consider TIVA as high PONV risk
extubate awake, fully reversed (aspiration risk)
postop adequare anti-emetics to resume PO intake & OHGAs
Endocrine input re: if fasting, insulin. dosing, BSL management

Question 21

At what level of potassium do we supplement in DKA?

Answer 21

if <4mmol/L, there’s a whole-body potassium deficit

Question 22

What are 3 potential phases of acidosis a pt may get if Mx for DKA?

Answer 22

initial ketoacidosis, then lactic acidosis from the shock, then may get hyperchloraemic acidosis if aggressive NaCl resus

Question 23

What is DKA characterised by?

Answer 23

It’s a medical emergency
Usually high glucose (except if euglycaemic DKA)
high ketones (acidic ketones produced through B-oxidation of fatty acids as alternate fuel for break, heart, liver & skeletal muscle when glucose/glycogen stores are exhausted)
low pH (metabolic acidosis) due to ketoacids
overall hypokalaemia due to glycosuria & urinary excretion of K+ with ketones (this may not be apparent on veg as intracellular K+ exchanged for H+)
may be a relevant TRIGGER to identify (eg. sepsis, trauma) requiring concomitant Ax & Mx

Question 24

What’s a particular consideration when intubating a pt with DKA?

Answer 24

maintain their pre-induction level of hyperventilation

Question 25

What parameters monitor in DKA?

Answer 25

pH
glucose
ketones (in DKA, >3mmol/L)
potassium
lactate
other electrolytes

Question 26

Why may need to continue giving insulin in DKA, even when the glucose normal?

Answer 26

keep ketones down

Question 27

What are the main cornerstones of DKA management?

Answer 27

Fluids (Hartmann’s or plasmalyte)
potassium-containing solution
insulin/glucose

Question 28

:) Is A1C a prognostic indicator? BGL?

Answer 28

yes- higher= higher risk of postop adverse events incl infections, MI, mortality

BGL >11 ass’d w incr risk periop wound infections

Question 29

:) risks of hypoglycaemia?

Answer 29

potentially life-threatening

transient cognitive deficits

arrhythmia/other cardiac events

Question 30

:) risks marked hyperglycaemia

Answer 30

volume & electrolyte disturbances (osmotic diuresis)
may have caloric & protein loss if under-insulinised
impaired wound healing/infection risk

Question 31

:) what’s a potential error in the management of periop insulin in pt w T1DM?

Answer 31

they are susceptible to ketosis so even if glucose level is normal, don’t withhold long-acting insulin (as would be appropriate for insulin-dependent T2DM pts who aren’t ketosis-prone)

Question 32

:) what’s hyperosmolar hyperglycaemic state?

Answer 32

a risk in T2DM in the setting of extreme stress- risk severe volume depletion & neurologic complications or ketoacidosis

Question 33

:) does intensive BGL control (<6.7 or <8.3mmol/L) in peri-op setting impact outcomes?

Answer 33

may be appropriate for some pts but meta-analysis of RCTs doesn’t show reduction in infectious or CV complications or mortality with intensive control but did show higher risk of hypoglycaemia

Question 34

:) signs/symptoms of hypoglycaemia?

Answer 34

hunger
anxiety

cognitive dysfunction
obtundation/seizures/coma (severe)

palpitations

sweating

tremor

paraesthesias

glycemic thresholds for these responses may be higher in pts with poorly controlled DM & lower if pts have repeated hypos

Question 35

:) pre-op instructions for non-insulin diabetes medication? when recommence postop?

Answer 35

-SGLT2 inhibitors stopped @ least 3 days before procedure (day of & 2 days before surgery) unless day procedure incl gastroscopy without bowel prep, in which case can just be stopped for the day of the procedure- but fasting before & after the procedure should be minimised.
-withhold morning of surgery:
metformin f risk of renal hypo perfusion
sulfonylureas & meglitinides risk hypoglycaemia
thiazolinediones may worsen fluid retention & peripheral oedema (may precipitate CCF)
DDP4 inhibitors & GLP-1 agonists may worsen postop state through reducing GI motility (but DDP4 inhibitors don’t worsen risk hypoglycaemia so may continue)

recommence most after surgery when commenced sufficient PO caloric intake, except metformin in pts with suspected renal hypo perfusion until known normal renal function or in pts with significant hepatic impairment or CCF, SGLT2-inhibitors until eating well-established & discharged, or GLP-1 agonists until PONV resolved. Avoid thiazolinediones if CCF, problematic fluid retention or liver function issues.

Question 36

:) are fingerpick BGLs reliable?

Answer 36

not in critically ill pts, those on vasopressors or those who are hypotensive- use venous or arterial

Question 37

:) management of pts with T2DM who develop preoperative hyperglycaemia?

Answer 37

can give supplemental correctional subcutaneous short-acting insulin every 4-6hrs (eg. 4 units if BGL 11-14)

Question 38

:) pros & cons of insulin infusion vs subcutaneous

Answer 38

infusion associated with more stable BGLs, may be because pts with hypoperfusion/vasoconstriction/hypothermia may have less reliable absorption. half-life of IV insulin short (5-10 mins) so more rapidly, reliably titrated allowing for more precise glucose control.

Question 38

:) pros & cons of insulin infusion vs subcutaneous

Answer 38

infusion associated with more stable BGLs, may be because pts with hypoperfusion/vasoconstriction/hypothermia may have less reliable absorption. half-life of IV insulin short (5-10 mins) so more rapidly, reliably titrated allowing for more precise glucose control.