Week 1/2 - B - Type 1 diabetes, DKA & hypoglycaemia Flashcards
Pancreatic beta cell destruction by T lymphocytes causing reduced insulin production resulting in hyperglycaemia What is this disease?
Type 1 diabetes mellitus
HLA (human leucocyte antigen) is the human version of the major histocompatibility complex (MHC), a gene family that occurs in many species. In humans, the MHC complex consists of more than 200 genes located close together on chromosome 6.
What are the haplotypes in diabetes?
HLA-DR3 and HLA-DR4
What are the types of antibodies the attack the islet cells of the pancreas?
Anti islet cell antibodies - mostly anti-GAD antibodies (anti-glutamic acid decarboxylase)
Which is more common, type 1 or type 2 diabetes?
Around 10-15% are type I
Around 85-90% are type II
Are children more likely to develop diabetes if their mother or father has it?
3 times more likely to develop diabetes if their father has it
How common is diabetes in patients with cystic fibrosis? What other diseases is diabetes common in? (usually autoimmune diseases) (name 4)
25% of patients with cystic fibrosis have diabetes
Thyroid disease,
pernicious anaemia,
coeliac disease,
addison’s disease
What is the diagnostic criteria for diabetes?
Venous plasma glucose tests
* Fasting glucose greater than 7mmol/l (fast for at least 8 hours)
* HbA1c greater than 48mmol/mol (6.5%)
* OGTT greater than 11.1mmol/l (measure 2 hours after 75g carboydrate load)
Random glucose - greater than 11.1mmol/l
What are the two main of the diagnostic tests for diabetes?
The random glucose at 11.1mmol/l and the fasting glucose at 7mmol/l
If the patient is asymptomatic the above criteria apply but must be demonstrated on two separate occasions (if symptomatic, then only one occassion)
What is the classic triad of clinical features associated with type 1 diabetes? What is the commonest presenting children in children?
Polyuria
Polydipsia
Weight loss
Secondary enuresis is the commonest symptom in children - (a child who has been trained and is dry in bed and has previously started wetting the bed then this is red flag of diabetes)
How does the unopposed glucagon production further exacerbate the hyperglycaemia?
Glucagon will cause increased gluconeogensis, glycogenolysis and lioplysis increasing blood glucose
What can increased glucose in the urinary system cause?
Can cause UTI infections as it provides a feeding source for bacteria
What is a common presenting factor of young children due to the fact they have unopposed rising glucose as there is a lack of insulin and therefore skeletal and other tissues do not have any glucose stores giving them a need for energy
Diabetic ketoacidosis
DKA often arises due to stress (ie infection) Stress causes increased hormonal levels of cortisol and adrenaline How does this cause increased serum ketones?
Cortisol cause stimulation of protein catabolism for gluconeogenesis and
adrenaline stimulates glucagon production causing increased lipolysis, gluconeogensis and glycogenolysis
The excess fatty acids causes is converted to ketones via the liver which causes the increased serum (and urine) ketones
How does a patient with DKA present?
Kussmaul breathing (deep laboured breathing)
Vomiting and abdominal pain
Dehydration - due to the glucose in the blood
Can have polyuria
What is the diagnostic criteria of diabetic ketoacidosis?
Diagnosis
- * Diabetes - hyperglycaemia >11.0mmol/l
- * Ketonaemia greater than 3mmol/l or 2+ on urine dipstick
- * Acidosis - venous blood pH <7.3
How is diabetic ketoacidosis treated?
What does each treatment correct?
- Give 500ml NaCl 0.9% IV over 15 minutes
- Give IV human soluble insulin infusion of 50 units in 50ml NaCl 0.9% at 0.1units/kg/hour
- Give IV KCl in NaCl 0.9% bag once potassium <5.5mmol/l
- Give IV glucose 10% at 125ml/hour once glucose <14mmol/l
- Continue insulin until ketones 0.3mmol/l, ph > 7.3 and venous bicarb >15mmol/l
How can a DKA cause depletion of body potassium levels?
High glucose levels in the blood spill over into the urine, taking water and solutes (such as sodium and potassium) along with it in a process known as osmotic diuresis
This can cause a depletion of potassium in the tissues however a hyperkalaemia
How can the treatment of DKA lead to changes in potassium levels?
insulin decreases potassium levels in the blood by redistributing it into cells via increased sodium-potassium pump activity
Most of the extracellular potassium will have been lost due to the osmotic diuresis and therefore there will be a hypokalaemia which is dangerous
What is the most common cause of death in the treatment of DKA?
Heart arrhythmia due to hypokalaemia ending in heart failure
When is potassium given in DKA?
Monitor potassium and levels decrease to less than 5.5mmol/l in blood then give IV potassium
When is glucose given in DKA?
Once the glucose levels decrease below 14mmol/l give IV glucose 10% glucose at 125ml/h to run alongside saline
How long should the fixed rate insulin (0.1 unit/kg/hour) be continued for in the treatment of DKA? What should happen with the patients regular long acting doses?
Fixed rate insulin should be continued until ketones 7.3 and venous bicarb >15mmol/l.
Continue patients regular long-acting insulin doses throughout treatment (withhold the short acting (bolus) insulin doses)
What is a child with dka at risk of when being treated?
At a high risk of cerebral oedema and therefore child should be treated with fluid replacement slowly and referred to paediatrics for management
State how esach of the DKA treatments help
- Give 500ml NaCl 0.9% IV over 15 minutes (corrects dehydration and restores BP)
- Give IV human soluble insulin infusion of 50 units in 50ml NaCl 0.9% at 0.1units/kg/hour (decreases blood glucose however will also drive potassium into the cells causing a hypokalaemia)
- Give IV KCl in NaCl 0.9% bag once potassium <5.5mmol/l (prevents potassium from going dangeriously low causing potentially fatal arrhythmias)
- Give IV glucose 10% at 125ml/hour once glucose <14mmol/l (prevent hypoglycemia once blood glucose level begin to return to normal.)
Continue insulin until ketones 0.3mmol/l, ph > 7.3 and venous bicarb >15mmol/l
