Carbohydrate disorders Flashcards
(29 cards)
What is the underlying effect that causes diabetes mellitus?
A deficiency of insulin action which leads to hyperglycemia (can be an absolute deficiency - type 1, or a relative deficiency of insulin action - type 2)
What are the insulin dependant tissues?
Fat, skeletal and cardiac muscles
What are the insulin independant tissues?
Brain, gut, pancreas, liver
Define Type 1 Diabetes
Insulin dependant diabetes - absolute deficiency of insulin due to destruction or degeneration of pancreatic B-cells
What is polydipsia?
Excessive thirst
What is polypuria?
Excessive urination
What is polyphagia?
Increased appetite - eating large amounts of food
What are the signs and symptoms of type 1 diabetes?
Polyuria, polydipsia, polyphagia Feeling tired and lethargic Itching, skin infections Blurred vision Unexplained weight loss
What are the 3 events in the pathogenesis of T1D?
- Initiating event
- Slow B-cell destruction
- Clinical disease
What happens in the initiating event in the pathogenesis of T1D?
Exposure to a virus or toxin may start the process of B-cell destruction in persons with a genetic predisposition
What happens in the slow B-cell destruction in the pathogenesis of T1D?
Over years B-cells are destroyed resulting in decreased production of insulin
What happens in the clinical disease stage in the pathogenesis of T1D?
Insulin secretion capacity falls below a threshold and the symptoms of T1D suddenly appear (80-90% of B-cells destroyed)
What are the 2 signs of untreated T1D?
Ketoacidosis and hyperglycemia
What is the transporter on fat, skeletal and cardiac muscle cells that transports glucose into the cell?
GLUT4 transporter
What is glucose uptake to muscle and fat cells dependant upon?
Activation of GLUT4 transporter
What is ketoacidosis?
Metabolic acidosis caused by abnormal accumulation of ketone bodies
Why is ketoacidosis experienced in diabetes?
Insulin is too low, does not activate GLUT4 transporter, liver uptake of glucose drops off so body goes into starvation mode, lipolysis is activated and large amounts of FA are released and the liver converts these to ketone bodies
What is experienced during ketoacidosis?
Fruity breath
Electrolyte imbalance (Na and K depletion)
Coma and death
How does hyperglycemia affect the kidneys?
High blood glucose = increased glucose filtered by kidneys
Glucose spills into urine
Excess glucose stays in lumen = osmotic diruesis - brings Na and K into urine
Causes frequent urination and thirst and dehydration with loss of electrolytes
Define type 2 diabetes
Non-insulin dependant diabetes - deficiency of insulin action due to changes in receptor number or post-receptor events
What are the symptoms of T2D?
Often no symptoms - dismissed due to ‘getting older’
Polydipsia, polyuria, polyphagia (less common)
Itching, skin infections
Blurred vision
Gradually putting on weight
What are the 2 causes associated with T2D?
Insulin resistance - due to defects in the receptor, or post receptor proteins
Dysfunctional pancreatic B-cells - inability of pancreatic B-cells to produce appropriate amount of insulin
What is insulin resistance characterised by?
Excessive hepatic glucose production
Decrease glucose uptake by muscle and adipose tissue
= hyperglycemia
When does hyperosmolar hyperglycemia state (HHS) occur?
In patients with T2D who have some concomitant illness that leads to reduced fluid intake
