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
Peak time for action of rapid-acting analogues
30-90 minutes
Duration of rapid-acting analogue actions
2-5 hours
Name a premixed insulin
Humulin M3
What is a premixed insulin
70% - rapid acting analogue
30% - normal insulin
Onset of Humulin M3
30 minutes
Peak action of Humulin M3
2-8 hours
Three ways we can treat type II diabetes
- Once daily basal insulin
- Twice daily mix-insulin
- Basal-bolus therapy
Advantages of basal insulin in type II diabetes
- Simple
- Can carry on with oral therapy
- Less risk of hypoglycaemia at night
Diasvntage of basal insulin in type II diabetes
- Doesn’t cover meals
2. Has to be used with long-acting insulin analogues which are costly
Advantages of pre-mixed insulin
- Can cover insulin requirements throughout the day as they have basal and prandial components
Disadvantage of pre-mixed insulin
- Requires consistent meals and exercise patterns
- Nocturnal hypoglycaemia
- Fasting hyperglycaemia
- Might have to be fine with a HbA1c goal of <64 mmol/mol
What is th best treatment therapy for T1DM
- Intensive basal-bolus insulin therapy
At what level do we begin insulin therapy for T2DM
> 9%
Ideal treatment approach for T2DM
- Basal insulin + oral therapy to reduce hypoglycaemia
Define hypoglycaemia
<3.9mmol/L
How is mild hypoglycaemia treated
Self-treated
Consequence of hypoglycaemia
BRAIN NEEDS ENERGY - neuroglycopenia
What is level 2 hypoglycaemia
- <3.0 mmol/L
Level one is <3.9
Autonomic symptoms of hypoglycaemia
- Trembling
- Palpitations
- Sweating
- Anxiety
- Hunger
Neuroglycopenic symptoms
- Difficulty concentrating
- Confusion
- Weakness
- Drowsiness
- Vision Changes
- Difficulty speaking
Headache + Nausea
Physiological changes to stop severe hypoglycaemia
- RELEASE OF ADRENALINE at 3.5mmol/L
2. Inhibition of insulin secretion at 4.6 mmol/L
Risk factors for hypoglycaemia in T1DM
- History of severe episodes
- Hb1Ac <48 mmol/mol
- Long duration of diabetes
- Renal impairment
- Extremes of age
Risk of hyperglycaemia in T2DM
- AGE
- Cognitive impairment
- Depression
- Duration of MDI insulin therapy
- Renal impairment
Target HbA1c in elderly people
- 58 mmol/mol in healthy elderly
- 64 mmol/mol in many chronic illnesses and current hypoglycaemia
- 69mmol/mol in end-stage chronic illness
How do we prevent hypoglycaemia
- Educate patients and caregivers on how to recognise and treat hypoglycaemia
- Instruct patients to report hypo episode stop doctor of history
- Blood glucose awareness training programme
What do people on basal-bolus insulin have to ensure
Check BG before each meal every day
Adjust insulin in relation to excercise
Treatment of hypoglycaemia
- Check for <3.9 mmol/L
- Treat with 15g fast acting carbohydrates
- Retest in 15 minutes to ensure glucose >4.0 and retreat
- Eat long-acting carbohydrate
- MDT support
- Change glucose targets
Why is hypoglycaemia a side-erect of insulin therapy
Insulin analogues can’t fully replicate/mimic the physiological actions of insulin itself
What is hyperosmolar hyperglycaemic state
COMPLICATION OF TYPE II DIABETES MELLITUS
Where high blood sugar causes high osmolarity without any ketoacidosis
What causes hyperosmolar hyperglycaemic state
- Lack of insulin
- Poor kidney function
- Old age
- Poor fluid intake
USUALLY PRECIPITATED BY INFECTION
Clinical presentation of hyperosmolar hyperglycaemic state
- Altered level of consciousness
- Blured vision, headaches, seizures, myoclonic jerking
- Hyperviscoity (clot formations)
- Dehydration
- Weight loss
- Nausea
- Weakness
POSTURAL HYPOTENSION
Differential diagnosis of hyperosmolar hyperdyclaemic state
DKA
However, in HHS glucose level are extremely high and ketone bodies are low (have fruity breath)
How is hyperosmolar hyperglycaemic state managed
- IV fluid 1L/h
- K+ replacement
- Insulin
Mechanism of pramlinitide
- Delays gastric emptying
2. Inhbitis glucagon release
Mechanism of alpha-glucosidase inhibitors
- Inhibits glucose absorption
2. Stimulation of GLP-1 release
Mechanism of Sulfonylureas
- Acute stimulation of insulin release
Mechanism of meglitinides
- Acute stimulation of insulin release
Mechanism of GLP1/DPP-IV inhibitors
- Stimulates insulin biosynthesis
- Inhibits B-cell apoptosis
- Stimulates B-cell differentiation
Mechanism of metformin
- Inhibits hepatic glucose production
2. Increases hepatic insulin sensitivity
Mechanism of thiazolidinediones
- Suppreses NEFA release
- Fat redistribution
- Modulates adipokine release
First line treatment for Type II diabetes
Metformin
If Metformin become ineffective what is done
Dual therapy with metformin and sulfonylureas/thiazolidinedione/DPP-4 inhibitor/SGLT-2 inhibitor/GLP-1 agonist etc
And then triple therapy
Lifestyle interventions for diabetes
- Compliance to treatment
- Lifestyle an patient education
- 30 min exercise a day
- Dietitian
- Local education programmes
Cons of using metformin
Difficult to maintain over long-term and costly
SIDE-EFFECTS
What consists of the combined injectable therapy
DONE WHEN TRIPLE THERAPY is not working:
1. Basal insulin + Mealtime insulin or GLP-1-RA
- Metformin
What is the recommended HbA1c target in treatment
<7.0%
What patients are given sulfonylureas
- Not overweight
- Require rapid response to hyperglycaemic symptoms
- Cannot tolerate metformin
What are incretins
Hormones secreted by intestinal endothelial cells in response to nutrient intake
How do incretins work
- Glucose-dependnat insulin secretions
- Postprandial glucagon suppression
- Slowing of gastric emptying
Name an incretin
GLP-1
What cell secretes GLP-1
enteroendocrine L cells
Effect of GLP-1 in the body
- SATIETY
- Decreased postprandial glucagon secretion
- Decreased glucagon causes decreased hepatic glucose output
- Enhances beta-cell insulin secretion
What GLP-1 analogue is given in diabetes
SC LIRAGLUTIDE
SC EXENATIDE
What agent prolongs activity of normal GLP-1
DPP-IV inhibitors (ORAL)
What is DPP-4
Dipeptidyl-peptidase 4 enzyme in vascular endothelial lining that inactivates GIP and GLP-1
Name a DPP-4 inhibitor
ORAL SITAGLIPTIN
How does SITAGLIPTIN effect weight
NO effect
Pros of DPP-4 inhibitors
- No effect on gastric emptying
2. Does not cause nausea + vomiting
Side-Effects of GLP-1 analogues
- Delay in gastric emptying
- Nausea and vomiting
- Weight loss
Name some thiazolidinediones
- PIOGLITAZONE
Benefits of TZDs
- Low risk of hypoglycaemia
Cons of TZDs
Increased CV risk, weight gain and lipid abnormalities
Benefits of SU
- Reduces CV risk
Cons of SU
- Hypoglycaemia
- Increased risk of CV events
- WEIGHT GAIN
Benefits of Metformin
- BP reduction
2. CV risk reduced
Cons of Metformin
Lactic acidosis
No weight change
Contraindications of TZD
- CCF
- High risk fractures
- Macula oedema
Name some SGLT-2 inhibtors
EMPAGLIFOZIN
Where are SLGT-2 receptors found
PCT
Role of SLGT-2 receptors
Co-tranpsort glucose and Na into renal cells for re-absorption
What channel causes movement of glucose out of renal epithelial cells back in to the blood
GLUT2
Pros of EMPAGLIFLOZIN
- Decreased CV death
Patient A wants to lose weight, what drugs would she NOT be given
- Pioglitazone (TZD)
- Insulin
- SU
- DPP-4I
What drugs can be given for patient A
- GLP1a
2. SGLT2i
Patient A does not want injectable treatment so what treatment should she be given
SGLT-2i (orally)
Side-effect of SLGT-2i
Causes thrush in women (mycotic)
Keep treatment going and manage thrush
Causes intravascular volume depletion so hypotension can occur in elderly
monitor BP
What factor reduces efficacy of SGLT-2i
Increasing renal impairment (they do not worsen it themselves)
At what eGFR should SGLT-2i be avoided
- <30 ml/min/1.73m^2
At what eGFR limit is empglifosin and canaglifosin given
> 45ml/min/1.73
At what eGFR limit is dapaglifosin given
> 60 ml/min/1.73
Genetic inheritance of type II diabtes
- Positive family history
2. Monozygotic twins!!