Diabetes Flashcards
What are the objectives of treatment in T2DM?
- Glycaemic control
- Reduce complications: Microvascular, macrovascular and side effects
What measure is good in judging the risk of complications (related to glycaemic control)?
HbA1c
What is the HbA1c target?
6.5-7.5% 48mmol/mol - 58mmol/mol. 7%
What is the UKPDS study and its importance?
The UK prospective diabetes study compared standard and intensive Tx in a large trial in people with recently diagnosed T2DM. Gives much of the evidence guiding current Tx recommendations. Intensive Tx was associated in a 25% overall reduction of Microvascular disease end-points, 33% reduction in albuminuria, 30% reduction in the need for laser treatment for retinopathy. These benefits persisted for many years after conclusion of the trial ‘ legacy effect’. Also showed that BP control is needed for the prevention of retinopathy.
What is the pathophysiology of T2DM?
- Insulin resistance
- As insulin resistance develops –> body response is to increase Insulin secretion hence early diabetes often associated with insulin hyper-secretion
3.Loss of the first phase of the normal biphasic insuin secretion
(even though bc of hypersecretion circulating Insulin levels are higher they are still inadequate to restore glucose homeostasis) - At time of diagnosis: AT LEAST 50% of beta cell mass and function have been lost
- In vitro hyperglycaemia and lipid excess are toxic to beta cells –> thought to cause further Beta cell loss and further deterioration of glucose homeostasis
- With time, insulin secretion declines - ‘The starling curve’ of the pancreas - time course varies widely between individuals
Relative insulin lack is associated with:
- Increased glucose production form the liver
- Reduced Insulin mediated glucose uptake into peripheral tissues
What is insulin resistance?
Inability of Insulin to produce its usual biological effect at physiological concentrations. Characterised by an impaired ability of Insulin to:
- Inhibit hepatic glucose output
- Stimulate glucose uptake into skeletal muscle
- Suppress lipolysis in Adipose tissue
What causes Insulin resistance in T2DM?
underlying mechanisms not fully understood but result from Nutrient excess.
- Intracellular trigylceride accumulates in the liver + skeletal muscles –> impedes the phosphorylation of the post-receptor insulin receptors substrate - IRS-1 –> reduce insulin action with regards to Glucose and Lipid Metabolism
- Insulin still able to activate the MAP kinase pathway - regulates a number of intracellular pathways involved in inflammation, cellular proliferation and atherosclerosis.
What is the current Tx/management guideline of T2DM?
Check current NICE guidelines
- Optimal Lifestyle management
- Metformin
Individualised Tx depending on (current lifestlyle, comorbidities, indivisualised HbA1c target, side effects, Tx complexity etc)
If established atherosclerotic CVD:
-GLP1 receptor agonist
SGLT2 inhibitor
If Heart failure or Chronic Kidney Disease:
-SGLT2 inhibitor
Pressing need to minimise weight gain / promote weight loss:
- GLP1 receptor agonist
- SGLT2 inhibitor
Need to avoid hypoglycaemeia
- DPP4 inhibitors
- Thiazolidinediones
Cost is a major issue:
- Sulphonylureas
- Thiazolidinediones
Triple therapy may be required
Beyond triple therapy:
- Insulin is required
- Several fixed dose oral combinations and fixed ratio injectable combinations of Insulin and GLP-1 receptor agonists
What is the first-line Tx in T2DM?
Dietary and lifestyle changes.
- Supported to lose at least 5% of their weight –> can enter remission
- Low glycaemic index foods
- Meditarranean diet (decrease salt intake <6g/day, wholegrans fruit veg, less red and processed meat, less sat fats)
- Limit alcohol intake <14 units/ week
- 150 mins of aerobic excersize + resistance training per week spread over min of 3 days
- Smoking cessation
When is Bariatric surgery indicated in T2DM and how effective is it?
Severe obesity (BMI >35kg/m2). Gastric bypass and sleeve gastrectomy. More effective than medical therapy and can be sustained for more years:
- Mean weight loss of 30%
Diabetes remission in up to 70% of people
-improves QoL
-Reduces risk of CVD and mortality
What pharmacological Tx options are there for T2DM?
- Metformin (first line Tx)
- Sulphonylureas, DPP-4 inhibitors, GLP-1 receptors agonists
- SGLT2 inhibitors
- Insulin
What pharmacological Tx options are there for T2DM?
- Biguinides: Metformin (first line Tx)
- Sulphonylureas
- DPP-4 inhibitors
- GLP-1 receptors agonists
- SGLT2 inhibitors
- Thiazolidinediones
- Alpha-glucosidase inhibitors
- Insulin
What drugs cause increased Insulin secretion?
Sulphonylureas, DPP-4 inhibitors, GLP-1 receptor agonists
What drugs excrete excess glucose load?
SGLT2 inhibitors
How can T2DM be prevented or delayed?
- Intensive diet and excersize programme
- Inc use of Metformin and TZDs (in adults at high risk)
- Difficult to maintain over long term+costly, unwanted side effects of medications
What is Metformin’s mode of action?
May involve: Activation of the enzyme AMP Kinase - which regulates cellular energy metabolism. METFORMIN INCREASES INSULIN SENSITIVITY:
- reduces rate of gluconeogenesis and hence hepatic glucose output
- increases insulin sensitivity
- does not affect insulin secretion
- does not induce hypoglycaemia
- does not predispose to weight gain
- it may also suppress appetite and stabilize weigh
What is the key difference beetween other pharmacological agents and Metformin?
- Least amount / no weight gain
What is the key difference between other pharmacological agents and Metformin?
- Least amount / no weight gain
What does Metformin do and how effective is it?
Increases insulin sensitivity . First line Tx in T2DM
- Lowers fasting plasma glucose by 2-4mmol corresponding to a fall in HbA1c of 11-22mmol/l (1-2%)
- In UKPDS metformin lead to an unexpected reduction in CV events
What are the adverse effects of Metformin and when is it contraindicated?
Adverse effects:
-GI side effects (10-20%) inc anorexia, nausea, abdmonial discomfort, diarrhoea.
( start at low dose and gradually increase. Slow release preparation appears to be better tolerated.)
- reduces GI B12 absorption but only rarely causes anaemia
Contraindications:
- Renal impairment (should not be started it eGFR <45mL/min per 1.73m2, stopped if eGFR falls <30mL/min)
-Cardiac failure
-Hepatic failure
due to risk of Lactic acidosis
- Avoided in people with history of alcohol Misuse
Should be stopped:
- Prior to Intravascular administration of Iodinated contrast agent (risk of renal failure and lactic acidosis)
- Surgery
- Intercurrent illnesses that may affect lactate clearance
When are Sulphonylureas indicated for Tx of T2DM and how effective are they?
- alternative first line agent (where Metformin is contraindicated or not tolerated)
- Can be used in combo with other oral agents or basal insulin (although usually stopped when individual requires short-acting Insulin at mealtimes)
Effectiveness:
- Reduce fasting plasma glucose by 2-4mmol/L corresonding to a 1-2% fall in HbA1c
- More effective than many other oral agents in the SHORT TERM (1-3yrs)
- Sulphonylurea effect wears off as the beta cell mass declines
What is the mode of action of Sulphonylureas?
Act on the beta cell to induce Insulin secretion. bind to the sulphonylurea receptor on the beta cell membrane –> closes the ATP sensitive K+ channels and block K+ efflux –> depolarisation–> promotes Ca++ influx –> stimulates Insulin release
- ineffective in people without a functional beta cell mass hence HAVE NO EFFECT IN T1DM
What are the adverse effects/ contraindications of sulphonylureas?
Adverse effects:
- Weight gain (1-4kg)
- Hypoglycaemia (1/5 of people but severe is uncommon), risk increases w excessive alcohol intake, older age, intercurrent infection
Contraindications: Should be used with care in people with:
- liver disease
- Kidney disease
What are meglitinides ?
Short acting agents that promote insulin secretion in response to meals.
Indicated in:
- Post prandial Hyperglycaemia with normal fasting glucose levels
-Older people when there is an imperative to avoid hypoglycaemia
-ROLE IN DIABETES NOT WELL ESTABLISHED + less effective than other drugs
Adverse effects:
- hypoglycaemia
- weight gain
What are Thiazolidineodiones mode of action?
-Increase insulin sensitivity
Mode of action: Alter cell membrane receptors for the insulin receptors
-Interacts with the PPAR-gamma nuclear receptor that
-Reduce hepatic glucose production
-Enhances peripheral glucose uptake
What is the only available TZD in many countries?
Pioglitazone. Still occasionally given in the UK
- Troglitazone was withdrawn bc of liver toxicity and rsiglitaozone withdrawn bc of concerns of CV safety
When are Thiazolidineodiones indicated?
- Monotherapy
- Combination with other diabetes drugs inc Insulin
- May benefit people with NAFLD
How effective are Thiazolidineodiones?
- Do not cause hypoglycaemia as monotherapy
- May take up to 3months to reach maximal effect
What are the adverse effects / contraindications of Thiazolidineodiones?
- Weight gain (most common) 5-6kg
- Fluid retention –> precipitation Heart failure
- Mild anaemia and osteoporosis resulting in peripheral bone fractures have been reported
What is the incretin effect and what is it mediated by?
The insulin response to oral glucose is greater than the insulin response to IV glucose.
The effect is mediated by 2 hormones released by the GI tract following eating:
- Glucagon like peptide-1 (GLP-1)
- Glucose dependant insulinotrophic polypeptide (GIP)
main action: increase glucose induced beta cell insulin secretion + suppress glucagon secretion. Also
- slow gastric emptying
- Induce satiety
Breakdown:
- Hormones have short half lives
- Broken down by enzyme dipeptidyl peptidase-4 (DPP4)
What happens to the incretin effect in T2DM and what is the consequence?
- Incretin effect impaired hence:
- Glucagon secretion increased (diminished intra-islet insulin) –> increased hepatic glucose output