Diabetes Flashcards
DM types 1 and 2 rare types: MODY
What tests are available for screening for diabetes in high-risk individuals?
- Random capillary blood glucose
- Random venous blood glucose
- Fasting venous blood glucose
- HbA1c
- Oral glucose tolerance test (venous blood glucose 2h after oral glucose load).
(lecture 19.4.18)
Other than identifying people at risk, give 3 ways of reducing the impact of diabetes and state whether they are primary, secondary of tertiary prevention.
(1. Identifying people at risk of diabetes)
2. Early prevention in those at risk (primary)
3. Early diagnosis of diabetes (secondary)
4. Supporting self-care for diabetes. (tertiary)
Give 3 examples of disability cause by diabetes
Blindess, renal failure, amputation.
How does the physical environment lead to diabetes?
Easy use of lifts, cars, remote controls and technology that leads to a sedentary lifestyle.
How does the economical environment lead to diabetes?
Fruit and vegetables, fitness classes, sports teams and gym memberships are expensive; it is cheaper to watch TV.
How does the sociocultural environment lead to diabetes?
People may have safety fears about walking around especially at night; family and social eating patterns affect diet.
What are the diagnostic criteria for diabetes mellitus?
- Symptoms of hyperglycaemia (eg polyuria, polydipsia and unexplained weight loss) and random blood plasma glucose ≥11mmol/l OR
- Fasting glucose ≥7mmol/L OR
- Oral glucose tolerance test 2h value ≥11mmol/L
(lecture 20.4.18; OHCM)
Why would a DM patient present with thirst?
Diabetes causes osmotic activation of the hypothalamus.
How does insulin bring glucose into cells?
Insulin binds to insulin receptors eg in muscle cells and adipose tissue which activates them. They cause vesicles containing glucose transporter to fuse with the cell membrane, allowing glucose to move into the cell, decreasing the blood glucose level.
(osmosis youtube)
How does glucagon affect blood glucose level?
Glucagon is produced in the liver and causes gluconeogenesis (production of glucose from lactate, glycerol and amino acids) and glycogenolysis (breakdown of glycogen to glucose), increasing the level of glucose in the blood.
What is HLA and how does it increase the risk of diabetes?
The human leukocyte antigen system is a group of genes on chromosome 6 which encode the major histocompatibility complex which is important for self-tolerance and recognising foreign molecules. This increases risk of T1 diabetes. It does not affect T2 diabetes.
Which type of diabetes mellitus is more common?
Type 2 (90%)
Describe the pathophysiology of type 1 DM.
A genetic abnormality causes a decrease in self-tolerance among T cells which target the beta cell antigens. This allows the T cells to attack the beta cells. Loss of beta cells -> loss of insulin -> less glucose moving into cells -> more glucose in blood.
What is self-tolerance?
Ability of the immune system to recognise self-produced antigens as a threat while mounting an immune response to foreign antigens.
Why would a patient with type 1 DM have weight loss, fatigue and polyphagia?
Glucose is not getting into cells, so it cannot be used to make energy, so fat and muscle are metabolised. The person feels hungry.
What causes glycosuria in type 1 DM?
Some of the excess blood glucose spills into the urine.
What causes polyuria in type 1 DM?
Excess blood glucose spills into the urinary tract and this has an osmotic effect, causing water loss in urine and therefore lots of urine production.
What causes polydipsia in type 1 DM?
(polydipsia = thirst). Water is lost in urine due to polyuria (which is due to glycosuria which is due to hyperglycaemia)
Describe the physiology of ketogenesis.
Lipolysis of fat in adipose tissue makes free fatty acids, which are converted to ketone bodies in the liver. They can be used by cells for energy and are acidic.
Give an example of a ketoacid.
Acetoacetic acid.
What is ketoacidosis?
Excess ketoacids eg acetoacetic acid in the blood which can lead to death via circulatory collapse. Characterised by hyperglycaemia (<50ml/L(, Ketones (>2), and acidosis (HCO3 <15mmol/l).
What is Kussmaul breathing and how is it caused by ketoacidosis?
Deep, laboured breathing. Acidosis occurs and causes the body to compensate by expelling CO2 in breaths.
How does type 1 diabetes cause hyperkalaemia?
In order to decrease the acidity of blood, H+ is moved into cells by the K+/H+ transporter, which also moves K+ out of the cell. In addition, the lack of insulin means the Na/K/ATPase pump does not function, so K stays in the blood.
Why do Type 1 diabetes patients have a high anion gap?
Buildup of ketoacids causing large gap in the number of unmeasured ions. *?
How can stress and infection lead to a worsening of symptoms of hyperglycaemia?
Epinephrine is released, causing glucagon release, which causes hyperglycaemia and therefore dehydration etc.
How can infection cause ketoacidosis?
The body needs more energy to fight the infection, so more ketone bodies are generated by lipolysis.
Give 5 signs of ketoacidosis.
hyperventilation, cerebral oedema, fruity breath due to acetone (nail polish remover), dehydration, hypotension, tachycardia.
Describe the management of ketoacidosis.
- Fluids for dehydration
- insulin to lower blood glucose
- electrolytes to prevent hypokalaemia.
When stable, treat underlying cause - this may be non-compliance so have discussion.
Follow DKA protocol for your hospital!
Why are people with diabetes more prone to pruritis vulvae and balanitis?
Excess glucose sugar provides a favourable environment for fungi such as candida albicans to grow and colonise the vagina (pruritis vulvae) and head of the penis (balanitis).
How does diabetes cause blurry vision?
Uptake of glucose and therefore water into the lens.
What features are suggestive of type 1 diabetes?
Lean body habitus Onset in childhood/adolescence (but can be any age) acute onset of osmotic symptoms prone to ketoacidosis high levels of islet autoantibodies.
What features are suggestive of type 2 diabetes?
Usually presents in over-30s, onset is gradual family history/ sibling with condition Hyperglycaemia can sometimes be controlled with lifestyle modification No HLA Complications eg MI.
Give one autoantibody associated with type 1 diabetes.
Anti GAD, pancreatic islet cell ab, islet antigen-2 ab.
Give 3 autoimmune diseases associated with type 1 diabetes.
Hypothyroidism, Addison’s disease, coeliac disease.
Give 5 symptoms of ketoacidosis.
Nausea, vomiting, mental status changes, weakness, weight loss, abdominal pain, drowsiness/confusion.
(lecture 20.4.18)
Why do you need to give K+ as part of treatment for DKA?
At first, K+ shifts out of cells with acidosis, causing hyperkalaemia, but with insulin and rehydration, blood K+ levels will fall which can cause life-threatening hypokalaemia.
Why are urea and creatinine raised in diabetes?
Pre-renal failure.
Who is more at risk of cerebral oedema from DKA and why?
Children because their brains have not shrunk yet in relation to their skull, so ICP would rise more.
Give 3 complications of DKA.
Adult respiratory distress syndrome (due to hyperventilation?)
Thromboembolism - venous and arterial
Aspiration pneumonia (drowsy/comatose patients)
(lecture 20.4.18)
What are the key microvascular complications of type 1 diabetes?
Nephropathy (30%)
Neuropathy
How is type 1 diabetes managed?
Insulin treatment: previously twice daily and had to control diet, now you can do basal bolus: medium-acting insulin plus pre-meal quick acting insulin. This requires the patient to calculate their carbohydrate intake exercise but means they can live more normally.
Other than hunger, give 3 symptoms of hypoglycaemia.
Loss of concentration, confusion, sweating, tremor, palpitations, (hunger), irritability (adrenaline release)
(lecture 20.4.18)
What are the stages of hypoglycaemia?
Glucose level: <3.8mM: autonomic symptoms (sweating, tremor, palpitations)
<2.8mM: Neuroglycopaenia symptoms (confusion, behaviour change, drowsiness)
<1.5mM: severe neuroglycopaenia (coma, convulsions, hemiparesis)
What is the advantage and disadvantage of setting higher glucose targets? Why do some patients prefer to set high glucose targets?
Reduces risk of hypoglycaemia but increases risk of diabetic complications. Hypoglycaemia can be frightening and uncomfortable to patients often prefer to risk complications.
What should you consider in a patient with symptoms of type 1 diabetes with a parent affected by diabetes?
MODY: Maturity onset diabetes of the young. A type of monogenic diabetes which accounts for 1% of diabetes. Often diagnosed in non-obese people under 25, is autosomal dominant and occurs from a single gene defect altering beta cell function.
(lecture)
What is the most common form of MODY and how is it treated?
MODY-3 in which a hepatic nuclear factor (HNF)1-alpha mutations alter insulin secretion and cause beta cell proliferation. It is treated with sulphonylurea tablets, not insulin. (lecture 20.4)
What would indicate MODY in a patient with hyperglycaemia?
Parent affected with diabetes
Absence of islet autoantibodies
No ketosis, good control on low-dose insulin - suggests non-insulin dependence
Sensitive to sulphonylurea.
What is C peptide and what is it used for in practice?
A component of natural (but not synthetic) insulin which is negative after prolonged type 1 diabetes but persists in type 2 and MODY.