Diabetes: Part II Flashcards
IN the fasting state where does all glucose come from
- LIVER (breakdown of glycogen)
Name three carbon precursors used in gluconeogenesis in the fasting state
- Lactate
- Alanine
- Glycerol
What is used as an energy source when insulin levels are low and glucose levels have run out
Free Fatty Acids are used by muscles for fuel
What is the post-prandial phase
Following needing - physiological need to dispose of nutrient load
What happens to rising glucose after eating
Increased insulin secretion
Suppresses glucagon
Where is glucose stored in post-prandial phase
- Liver
- Muscles
Used to replenish glycogen stores in the liver and muscle
What surpasses lipolysis and NEFA levels
High insulin and glucose
What connects the alpha and beta cells together
Paracrine crosstalk
What is glucagon inhibited by
Insulin
What cell secretes insulin
Beta cell
What cell secretes glucagon
Alpha cells
How is insulin secreted by the beta-cell
- Glucose enters through GLUT2 glucose
- Glucokinase breaks down glucose -> Increasing ADP/ATP ratio
- Increase in ADP/ATP causes calcium channels to open
- Calcium ions cause secretory insulin granules to be moved out by exocytosis
How does insulin cause glucose to enter muscle and fat cells
- Insulin binds to fat cells
- Causes intracellular GLUT4 vesicles to insert into the plasma membrane
- Glucose enters into cell via GLUT4
What processes are suppressed by insulin
- Glycogenolysis
- Gluconeogenesis
- Lipolysis
- Breakdown of muscle
Role of glucagon
- Increased glycogenolysis/gluconeogenesis
- Reduced peripheral glucose uptake
- Stimulate release of gluconeogeneic precursors (glycerol, Alanine and Lactate) for lipolysis
Two ways diabetes mellitus causes mortality
- Acute hyperglycaemia (DKA + Hypersomolar coma)
2. Chronic hyperglycaemia
Describe the pathogenesis of type I diabetes
- Insulin deficiency disease caused by loss of beta cells due to autoimmune destruction
- Beta cells express HLA which activate mediated immune response
INSULITIS
What antibodies of type I diabetes are found in the blood
- ICA
- GAD65
- Insulin
What is pre-diabetes
- Loss of first-phase insulin response
2. Glucose intolerance develops
What percentage of beta cells remain in diabetes
10%
What is the consequence of insulin secretion in type I diabetes
- Continued breakdown of liver glycogen
- Unrestrained lipolysis and skeletal muscle breakdown to provide gluconeogenic precursors
- Inappropriate increase in hepatic glucose output and suppression of peripheral glucose intake
What is the consequence of rising glucose concentration in type I diabetes
Exceeds threshold of 10mM causing urinary glucose
Failure of treating insulin in type I diabetes
- Increase in circulating glucagon -> increases glucose further
- Increased cortisol and adrenaline
- Ketoacidosis
How do free fatty acids effect glucose uptake
Reduces it
What happens to FFAs
Transported to the liver for gluconeogenesis where they are oxidised to ketone bodies
Name three ketone bodies
- Beta hydroxybutyrate
- Acetoacetate
- Acetone
Define type II diabetes
- Increased resistance to insulin by muscle and fat cells as intra-abdominal fat increases (sensitivity to insulin decreases)
- Decreased insulin secretion (insulin levels are very low)
How is glucose output affected in type II diabetes
Raised
How does glucose effect insulin levels in the blood
- Causes increase in insulin normally
- No change in insulin in type II diabetes
Insulin levels are lower in diabetics
How does insulin secretion change over time
- During pre-diabetes (impaired glucose tolerance), insulin secretion increases to try bring out the same effect
- Body gives up as glucose levels are not going up so insulin secretion decreases in actual diabetes
What happens to fasting and postprandial glucose in diabetes type II
Increases exponentially as insulin secretion decreases
Effect of decreased insulin secretion in type II diabetes
- Reduced muscle and fat uptake after eating
- Suppression of lipolysis is failed -> Free Fatty Acids
- HIGH glucose output after a meal
Overview of type I diabetes
- Absent insulin secretion
- Unrestrained glucose + ketone production
- Hyperglycaemia + plasma ketone increased
GLYCOSURIA and KETONURIA
Does DKA occur in type 2 diabetes?
No because insulin levels are low but not non-existent so there is suppression in lipolysis -> free fatty acids -> ketone bodies
When can DKA occur in type two diabetes
High levels of adrenaline
Why does insulin secretion become impaired in type II diabetes
- Genetic predisposition
- Deposition of amilyn peptides within the beta cell
- Glucotoxicity hyperglycaemia inhibits insulin secretion
LIPID DEPOSITION in pancreatic islets prevent normal function
When is rapid acting insulin given
At meal-time
Name some prandial/meal-time insulins
- Insulin lispro (NPH insulin)
- Insulin glulisine (Insuline glargine)
- EDTA/citrate human insulin (Insulin determir)
- Insulin aspart (insulin degludec)
Why does glucose need tone tightly controlled
Risk of retinopathy
What is basal bolus therapy
- Insulin pumps that try mimic the physiology of insulin
How is insulin pump delivered into th body
SUBCUTAENOUSLY
Why is basal insulin given throughout the day
Control blood glucose between meals particularly at night
What is the fasting blood glucose that needs to be achieved by the basal insulin
5-7 mmol/L
Describe treatment of type 2 diabetes mellitus
- Basal insulin initially introduced before prandial insulin is given (mimics meal-time insulin secretion)
- Long-acting basal insulin given
- Premix insulins availbale
Name an intermediate-acting insulin
Human basal insulin (NPH)
How long does it take for intermediate-acting insulin to act
90 minutes
Peak action of intermediate-acting insulin
2-4 hours
Duration of intermediate acting insulin
24 hours
Name a basal analogue
Deter or Glargine U100
Benefit of basal analogues
Keeps insulin secretion at steady state
Onset of basal analogues
1-2 days for 24 hours
Name three rapid-acting analogues
- Insulin aspart
- Insulin lisper
- Insulin glulisine
Onset for rapid-acting analogues
10-20 minutes