Diabetes Cases Flashcards
diabetes is confirmed by
fasting plasma glucose >7.0mM
2 hour plasma glucose in a GTT of >11.1mM
HbA1c > 6.5% (48mmol/mol) - not useful if in people with end-stage chronic kidney disease
CASE 1
- 16-year-old unconscious
- Acutely unwell a few days
- Vomiting
- Breathlessness
Data
- pH: 6.85
- PCO2: 2.3kPa (N: 4-5)
- PO2: 15kPa
QUESTION 1: What is the acid/base abnormality?
Low PH
low PCO2
- Metabolic acidosis
LOW pH= ACIDOSIS – this means there are excess H+ ion >> this will lead to a LOW CO2
NOTE: If you have a LOW CO2, this means there is LOW bicarbonate
HCO3- + H+ >>> CO2 + H20
More Data
- Na: 145
- K: 5
- U: 10
- pH: 6.85
- Glucose: 25
What is the osmolality?
osmolality = (cations (Na, K) + anions (Cl, HCO3) + urea+ glucose)
But Since anions = cations, this can be reduced to: 2 x (Na + K) + Urea + Glucose
= 335
define Anion Gap + equation + what is normal anion gap
Cations (Na/ K) = Anions (Cl, HCO3, others)
‘Others’ are known as the anion gap
ANION GAP= Na+ + K+ - (Cl- + HCO3-)
A NORMAL anion gap is ~ 18mM
acidosis + high anion gap means:
there are extra ‘other’ anions in the patient’s blood e.g. KETONES/Lactate
acidosis + normal anion gap means:
this is due to the a HIGH Cl-
commonest causes of metabolic acidosis
o DKA -1st
o Lactic acidosis – 2nd (e.g. sepsis)
o if neither of these consider poisons
- 19-year-old known to have T1DM for several years presents unconscious
- Results:
o pH: 7.65
o PCO2: 2.8kPa
o HCO3: 24mM (NORMAL)
o PO2: 15kPa
What is the acid-base abnormality
Respiratory Alkalosis
HIGH pH: ALKALOSIS, LOW CO2: respiratory
indicates: primary hyperventilation
Treatment is to help slow their breathing to bring them back to normality
- 19-year-old known to have T1DM for several years presents unconscious
- Results:
o pH: 7.65
o PCO2: 2.8kPa
o HCO3: 24mM (NORMAL)
o PO2: 15kPa
Na: 140, K: 4.0, HCO3: 24, Cl: 100, Glucose: 1.3mM
What is the anion gap? + What is the diagnosis?
ANION GAP= Na+ + K+ - (Cl- + HCO3-) = 20mM
Respiratory Alkalosis
- Anxiety caused by hypoglycaemia because they are diabetic patient
but if they were non diabetic: Anxiety may just lead to respiratory alkalosis in a non-diabetic patient- COMMON CAUSE
what can cause respiratory alkalosis commonly + how do you treat this
Anxiety
To treat: give them a BROWN BAG to rebreathe in- CO2 goes up, patient calms down. Slow down the breathing.
what happens to calcium when PH goes up
When pH goes UP, the ionised calcium FALLS.
When the pH goes up, the calcium sticks more avidly to the albumin. So the ionised calcium falls
*so alkalosis is associtaed iwth both hypoklaaemia and hypocalcaemia
why do people hyperventilating get hypocalcaemic signs
hyperventilating: Respiratory alkalosis so PH goes up
When the pH goes up, the calcium sticks more avidly to the albumin. So the ionised calcium falls = hypocalcaemic signs
CASE 3
-60-year-old man presents unconscious to casualty, with a history of polyuria and polydipsia.
Investigations reveal:
- Na: 160, K: 6.0, U: 50, pH: 7.30, Glucose: 60
QUESTION 6: What is the osmolality? + what is the diagnosis
osmolality = 2 x (Na + K) + Urea + Glucose
2 x (160 + 6) + 50 + 60 = 332 + 110 = 442mosm/kg (very high osmolality)
undiagnosed DM >>> hyperosmolar non-ketotic coma (HONKC)/hyperosmolar state (HHS
(PH is not too bad (not very acidotic) so unlikely to be DKA + long-standing DM will not present with DKA
treatment for
hyperosmolar non-ketotic coma (HONKC.)/hyperosmolar state (HHS)
-0.9% NORMAL saline = 0.9g/ 100ml of NaCl.
GIVE THIS SLOWLY: 500ml over 1 hour + reassess and continue until visible JVP (euovolaemic)
If patient is VERY dehydrated can give 1L of saline over 1 hour - like in this case
what is the worry about giving too much fluid quickly
can lead to cerebral and pulmonary oedema, especially in the elderly
how do you treat hyperglycaemia in T1DM and T2DM
T1DM management involves giving lots of insulin
T2DM management involves very slow infusion of fluids + observe + then give insulin >> do not want to precipitate pulmonary oedema
what happens if you give insulin first in hyperosmolar state in T2DM:
circulatory collapse: insulin will pump whatever is in the circulation into the cell. So, the BP will fall.
must give fluids first and then give insulin as they are insulin resistant
CASE 4
- 59-year-old man known to have T2DM on a good diet and metformin presents to casualty unconscious
- Urine negative for ketones
- Na: 140, K: 4.0, U: 4.0, pH: 7.1, Glucose: 4.0
- PCO2: 1.3kPa, Cl: 90, HCO3: 4.0
What is the osmolality? + anion gap + What is the acid/ base abnormality?
- 2 x (140 + 4) + 4 + 4 = 296- high osmolality
- 140 + 4 – 90 – 4= 50- large excess of anions
- Metabolic acidosis
EXCESS ANIONS- examples
- KETOSIS (excess ketones)
- Methane: Meth drinks
- Ethanol: Ethylene glycol + Other organic solvents
- Lactate: Sepsis + Metformin overdose
in which 2 scenarios can excessive metformin causes lactic acidosis and how does metformin cause lactic acidosis
Lactate accumulates in large excess of metformin >> lactic acidosis: Metformin inhibits hepatic gluconeogenesis- gluconeogenesis (the conversion of lactic acid to glucose in the liver)
Metformin overdose + occurs in people
- who have acute renal failure
- suicide attempt
excess lactic acid is normally excreted by the kidneys, but in renal failure the kidneys cannot handle the excess lactic acid which is why people with renal failure are affected
Definition: T2DM
T2DM: Fasting glucose ≥ 7.0mM
Fasting plasma glucose:
- FPG: ≤ 6.0mM is NORMAL
- IFG: 6.1-6.9mM
- DM: ≥ 7.0mM
GTT: plasma glucose ≥ 11.1mM at 2 hours
Impaired glucose tolerance on GTT: 7.8-11.0 at 2 hours
acid base abnormality in DKA + effect of Kausmaal respiration + what should be done
- If a patient has DKA, then the PCO2 + pH will FALL – the acid will go up leading to metabolic acidosis (without compensation)
If he starts to get Kausmaal respiration (hyperventilate), the pH will start to normalise as the CO2 will start to drop more
Give this patient insulin to help turn off the acid production
- If a patient has acute severe asthma and has an acute asthmatic attack what acid base abnormality will be seen
there will be a rapid rise in CO2 leading to acute respiratory acidosis and hypoxia
define compensation in acid base abnormalities
Compensation is IMPROVING the pH by WORSENING the CO2 (either VERY low or high)
Metabolic acidosis- over-breathe to compensate
Chronic respiratory acidosis + acute respiratory acidosis- not breathing enough and compensate by retaining HCO3
DKA vs HHS
DKA more common in T1DM, prominent PH acidosis
HHS- more common in T2DM, extremely high osmolarity
DKA criteria
pH < 7.3
Plasma Glucose >11mM
Blood Ketones>3mM (2+ in urine).
Sx and precipitants of DKA
Symptoms: confusion, Kussmaul breathing, abdominal pain, nausea, vomiting
- Precipitants include infection, surgery, missed insulin doses, trauma
- Management
Management of DKA
Criteria for HHS
pH > 7.3,
Osmolarity > 320mOsm,
Blood Glucose > 30mM
What duration does HHS develop over?
Few days
Management of HHS
A to E approach
Fluid replacement FIRST to prevent low BP : 0.9% saline over 1 hr
Then IV insulin >> Only if >1 mmol/L ketones
0.05u/Kg/hr fixed rate
Monitoring
§ Serial U+Es and glucose readings
differences between HHS and DKA
- DKA- T1DM and HHS - T2DM
- HHS- higher osmolaity, higher glucose, high PH
- DKA- lower PH + presence of ketones >3
good way to remember acid base status
when do you need 2 abnormal readings for diagnosis of diabetes
In asymptomatic patients, 2 abnormal readings are required for diagnosis.
Conditions where HbA1c may not be used for diagnosis:
haemoglobinopathies
haemolytic anaemia
untreated iron deficiency anaemia
suspected gestational diabetes
children
HIV
chronic kidney disease
people taking medication that may cause hyperglycaemia (for example corticosteroids)
