Diabetes: type 1 and others Flashcards
Presenting features of type 1 diabetes?
Polydipsia Polyuria Weight loss and fatigue Hunger Blurred vision
What type of eye problems occur in type 1 diabetes and why do they occur?
Altered acuity
Water and glucose uptake into lens
When presented with a patient with diabetes, what are the suggestive features to look for indicating they likely have type 1?
Younger onset
Lean body habitus
Acute onset
Autoantibodies against islets are found in the blood
Ketoacidosis: rare in type 2
What 3 symptoms are red flag symptoms that you should start insulin right away?
Weight loss
Sudden onset of symptoms
High levels of ketones
Pathogenesis of type 1 diabetes?
They start with normal beta cells
Something triggers destruction of beta cells, such as surgery, infection, often unknown
Beta cells get damaged and over time you lose function of beta cells
No beta cells = no insulin
When beta cell function gets less than 10% symptoms start
There are 3 antibodies known to be involved in type 1 diabetes. Name them?
Anti-GAD (glutamate decarboxylase)
Pancreatic islet cell antibody
Islet antigen-2 antibody
Does diabetes cause low or high blood glucose levels? Why?
Diabetes mellitus of any cause results in HYPERglycaemia
Due to dysfunction/insensitivity to insulin
What effect do these hormones have on blood glucose:
- insulin
- glucagon?
Insulin: LOWERS glucose
Glucagon: RAISES glucose
Why does lack of insulin cause blood glucose to rise?
Lack of insulin means muscle/other cells can’t take up the glucose in the blood stream
They send signals to liver to release/make more glucose because they’re not getting any!
So liver releases/makes more glucose
Thus, blood glucose rises
IN ADDITION
Insulin is normally involved in glucose –> glycogen, no glucose means glucose remains loose in blood stream rather than being stored
Why does type 1 diabetes cause weight loss?
Lack of insulin means cells of body are starved of glucose
So the body breaks down other things to fuel the cells, like fats
Describe how ketones are formed in ketoacidosis?
Lack of insulin means body breaks down fats into glycerol and free fatty acids
The free fatty acids go to the liver where they are used as fuel to power gluconeogenesis
During this they are oxidised to become ketones
What is ketoacidosis? How does it cause death?
Build up ketones due to diabetes
Ketones are weak organic acids, build up of them is toxic
The cause a metabolic acidosis, anorexia and vomiting
The person gets into a vicious cycle of dehydration, hyperglycaemia and increasing acidosis
Until circulatory collapse and death
Also cerebral oedema can occur
Ketoacidosis can be described as a triad of…
- hyperglycaemia
- ketones
- acidosis
Clinical features of diabetic ketoacidosis (DKA)?
These symptoms develop over days
Polyuria + dipsia Nausea and vomiting Weight loss Abdo pain Fruity breath
Dehydration
Hypotension + compensatory tachycardia
Coma
Investigations of DKA?
Blood:
- hyperglycaemia
- low HCO3-
- raised ketones
- low K+, Mg, P
Urine: raised ketones
Management of DKA?
ABCDE
Fluid replacement:
0.9% NaCl 100ml/kg
2 boluses
Electrolyte replacement:
K, Cl, Na
Insulin:
Actrapid
0.1 microgram/kg/hr
Replace glucose: because insulin can reduce glucose a lot, don’t want a hypo
5% dex when glucose has come down to 12mmol/L
Treat precipitating illness i.e. infection
What does insulin do to treat DKA?
Inhibits lipolysis, ketogenesis, acidosis
Reduces hepatic glucose production
Increases tissue glucose uptake
Other causes of ketoacidosis?
Alcohol
MI?
Complications of DKA?
Cerebral oedema (more in kids)
Pulmonary oedema
Thromboembolism
Hypokalaemia
Iatrogenic hypoglycaemia
What is the usually the cause of death in type 1 diabetes? Is it earlier than average?
CVS disease
Some patients lose 10-20 years, but these days many patients live full lives, if they are responsible with their treatment
What microvascular complications can occur with diabetes?
Nephropathy
Retinopathy
Neuropathy
Management of type 1 diabetes?
Insulin injection:
- twice daily
- basal bolus before each meal
Controlled diet
Self-monitoring of glucose
Every day!
In diabetic patients, how does HYPOglycaemia occur?
If they over-inject with insulin blood sugar levels can become too low
Clinical features of HYPOglycaemia?
Shaking Tachycardia Sweating Dizziness Anxious
Cerebral dysfunction: loss of concentration, confusion, coma
What is the HbA1c test?
Measure of average blood glucose levels over last 3 months
List some other causes of diabetes?
Warning: there are tons…
Genetic causes:
- MODY
- permanent neonatal diabetes
Exocrine pancreas disease:
- pancreatitis
- haemochromatosis
- pancreatic cancer
- amyloidosis
- cystic fibrosis
Endocrine pancreas disease:
- acromegaly
- Cushing’s
- Phaeochromocytoma
Drugs
What does MODY stand for?
Maturity onset diabetes of youth
What is MODY?
Genetic causes of diabetes
Diagnosed in the under 25s
A single gene defect altering beta cell dysfunction
How can you differentiate MODY from type 1 diabetes?
MODY:
- non-insulin dependent
- strong family history
- no islet antibodies
- no ketosis
- C-peptide measurable
Type 1:
- highly insulin dependent
- not really that familial
- islet antibodies seen
- C-peptide not present
Inheritance pattern of MODY?
Autosomal dominant
What is C-peptide? What is its significance in diagnosing diabetes?
Part of the structure of insulin
Type 1 diabetes: C-peptide is not seen
Type 2 diabetes + MODY: C-peptide is seen
Clinical presentation of permanent neonatal diabetes?
Also say why these symptoms occur!
Small baby: due to inability to lay down muscle and fat
Epilepsy: due to high glucose in the brain
What is lipodystrophy?
Problems laying down fat
They have no fat at all
Can cause diabetes
How does acute pancreatitis cause diabetes?
Transient hyperglycaemia caused by increased glucagon secretion
Glucagon RAISES blood glucose
How does chronic pancreatitis cause diabetes?
Formation of protein plugs that block ducts in the pancreas
These create perfect sites for calculi to form too
The plugs and calculi prevent insulin getting out of the pancreas, lack of insulin = diabetes
How does amyloidosis cause diabetes?
Deposition of amyloid in pancreas, damages it and blocks ducts
Insulin production is impaired, and ducts are blocked
Lack of insulin = diabetes
How does haemochromatosis cause diabetes?
Deposition of iron in pancreas, damages it
Insulin production is impaired
Lack of insulin = diabetes
How can pancreatic cancer cause diabetes? What other blood glucose related problem can it cause?
Indirectly
Treatment of pancreatic cancer often necessitates pancreas removal
They will have no insulin or glucagon production
Leading to diabetes (lack of insulin) and a proneness to hypoglycaemia (lack of glucagon)
How does cystic fibrosis cause diabetes?
CTFR gene mutation, problems with transmembrane conductance and thus poor regulation of Cl- secretions
Viscous secretions clog up pancreas impairing its function
Lack of insulin = diabetes
How does acromegaly cause diabetes?
Too much growth hormone causes insulin resistance!
This causes raised blood glucose, and inability of glucose to enter tissues
= diabetes
How does Cushing’s cause diabetes?
Too much cortisol causes insulin resistance!
This causes raised blood glucose, and inability of glucose to enter tissues
= diabetes
How does Phaeochromocytoma cause diabetes?
Tumour that secretes excess catecholamines (adrenaline, noradrenaline)
These cause increased gluconeogenesis and decreased glucose uptake by tissues
Which drugs are known to cause diabetes?
Glucocorticoids
Thiazides
Protease inhibitors (used in HIV)
How does glucocorticoid therapy cause diabetes?
As in Cushings, increased insulin resistance
