Diabetes Flashcards
What is the main characteristic of diabetes?
The body can’t control blood glucose levels
What is the role of the pancreas?
To secrete hormones in response to blood glucose levels
Outline insulin release
- Glucose is transported into the beta cell by GLUT2.
- Glucose is converted to glucose-6-phosphate (glycolysis).
- ATP produced.
- K+ channels in cell membrane close.
- Increase in K+ produces +ve charge inside membrane (a depolarisation)
- Voltage-gated Ca++ channels open, Ca++ enters cell
- Increase in intracellular Ca++ concentration triggers secretion of insulin via exocytosis.
Outline the insulin receptor and glucose transport process
- Insulin binds to the alpha subunits on the insulin receptor.
- Conformational change induced, transmitted to the beta subunits.
- Beta subunits phosphorylate > cascade of phosphorylation and dephosphorylation reactions.
- Translocation of GLUT4 to cell membrane
- Glucose uptake increases
- GLUT4 repackaged into vesicles when glucose levels fall and insulin goes away.
When is glucagon secreted?
When blood glucose levels are low
What does glucagon do?
Triggers the breakdown of glycogen and promotes gluconeogenesis
What does glucagon activate?
Adipose lipase
What does insulin do in the muscles?
Promote: gycolysis, glycogenesis and amino acid uptake
Inhibit: glycogenolysis, protein degradation and amino acid release
What does insulin do in adipose tissue?
Promote formation of glycerol
Inhibit lipolysis
What does insulin do in the liver?
Promote: glycolysis, glycogenesis and fatty acid synthesis
Inhibit: glycogenolysis, gluconeogenesis and ketogenesis
What does glucagon do in the muscles?
Promote: glycogenolysis, protein degradation and amino acid release
Inhibit: gycolysis, glycogenesis and amino acid uptake
What does glucagon do in the adipose tissue?
Promote lipolysis
Inhibit formation of glycerol
What does glucagon do in the liver?
Promote: glycogenolysis, gluconeogenesis and ketogenesis
Inhibit: glycolysis, glycogenesis and fatty acid synthesis
What does insulin do, in general?
Promote the use of carbohydrates for fuel and inhibits the use of fats and proteins
What does glycogen do, in general?
Promote the breakdown of glycogen, fats and proteins for fuel to raise blood glucose levels
What is diabetes mellitus (diabetes type 1)?
The deficiency or absence of insulin
Pathogenesis of diabetes mellitus (type 1 diabetes)
Autoimmune: immune system damages beta cells
Risk factors: genetic and environmental triggers
What percentage of all diabetes cases is diabetes mellitus (type 1)?
10%
How is diabetes mellitus (type 1 diabetes) managed?
Regular insulin injections and maintenance of normal blood glucose levels
What are the symptoms of type 1 diabetes (mellitus)?
Excessive urination Headaches Blurred vision Slow healing Constant hunger Mood swings Leg cramps Weakness and fatigue Unexplained weight loss Excessive thirst
How is diabetes mellitus (type 1 diabetes) diagnosed?
Detection of glucose in the urine
Glucose tolerance test
Blood insulin levels
How is type 1 and type 2 diabetes differentiated?
C-peptide test
What is diabetic ketoacidosis?
A condition of untreated diabetes, in which there is a build-up of acetoacetate and beta-hydroxybutyric acid.
Treated by insulin and fluids
What are the signs and symptoms of diabetic ketoacidosis?
Reduced consciousness, fruity smelling breath, nausea, vomiting, coma, death
How is diabetic ketoacidosis diagnosed?
Detection of ketone bodies in blood and urine
What are the major consequences of untreated diabetes (hyperglycaemia)?
Diabetic nephropathy
Diabetic retinopathy, cataracts and glaucoma
Diabetic neuropathy
Complications of diabetic retinopathy?
Micro-aneurysms -> spots
Swelling and distortion of blood vessels -> reduced blood flow to retina»_space; new blood vessels
Scar tissue > retinal detachment
How does diabetes cause glaucoma?
Osmotic swelling damages optic nerve fibres
How does diabetes cause cataracts?
Excess sorbitol > swollen lense»_space; apoptosis in lens epithelial cells
Outline the pathophysiology of diabetic neuropathy
Hyperglycaemia damages nerve blood vessels > nerve damage.
Lose ability to feel sensations OR feel sensations that aren’t stimulated by the environment.
Complications: ulcers, infections, amputation
What is polyol?
Increased glucose levels > converted to sorbitol, then to fructose. Increased oxidative stress
What are the symptoms of hypoglycaemia?
Pale, shakiness, excessive sweating, palpitations, loss of consciousness, seizures
What metabolic pathways are activated in untreated type 1 diabetes?
beta-oxidation
Gluconeogenesis
Ketogenesis
What is type 2 diabetes caused by?
Insufficient insulin production or resistance
What are the risk factors for type 2 diabetes?
Family history
Overweight
Ethnicity
What is gestational diabetes?
Abnormal glucose tolerance during pregnancy.
Goes back to normal once baby is born
What is MODY?
Maturity Onset Diabetes in the Young:
Monogenic diabetes caused by autosomal dominant mutations, non-insulin dependent
Why does type 2 diabetes develop?
In high sugar diets, the pancreas has to constantly secrete insulin to control blood glucose > beta cells work to death.
> cells stop responding to insulin
