Diabetes Flashcards
In fasting state where does all glucose come from?
Liver
Bit from kidney
Breakdown of glycogen
Gluconeogenesis
What happens when we have high insulin and glucose levels in the body?
High insulin and glucose levels suppress lipolysis and levels of non-esterified fatty acids (NEFA or FFA) fall
What are the 3 carbon precursors to synthesise glucose?
lactate, alanine and glycerol
In fasting state where is glucose delivered to?
insulin independent tissues, brain and red blood cells
How many hours of glucose store do we have?
6
After eating what happens?
Rising glucose (5-10 min after eating) stimulates insulin secretion and suppresses glucagon
Where does the ingested glucose go once we eat?
40% of ingested glucose goes to liver and 60% to peripheral tissue, mostly muscle
Ingested glucose helps to replenish glycogen stores both in liver and muscle
Where is the site of insulin and glucagon secretion in endocrine pancreas?
Islets of langerhans
What secretes insulin?
Beta cell
What secretes glucagon?
Alpha cell
What happens when we have high amounts of insulin?
– beta cells keep alpha cells in a state of chronic inhibition – paracrine effects
paracrine ‘crosstalk’ between alpha and beta cells is physiological, ie local insulin release inhibits glucagon an effect lost in diabetes
What is diabetes mellitus?
A disorder of carbohydrate metabolism characterised by hyperglycaemia
Main issue= High sugar levels
High sugars for long period of time – causes complications
Glucose – draws water across cell membranes – lot of glucose being stored not in the right place
Start to pee a lot of water
Make glucose from ketones – lose more water ketones acidic
Vomit = lose more water
Diabetic ketoacidosis
How does diabetes mellitus affect cause morbidity and mortality?
Acute hyperglycaemia: if untreated leads to acute metabolic emergencies diabetic ketoacidosis (DKA) and hyperosmolar coma (Hyperosmolar Hyperglycaemic State )
Chronic hyperglycaemia: leading to tissue complications (macrovascular and microvascular)
Side effects of treatment- hypoglycaemia
What are some serious complications associated with diabetes?
Diabetic retinopathy: Affects over one-third of people with diabetes; leading cause of vision loss in working-age adults1
Diabetic Nephropathy: Leading cause of end stage renal disease
Stroke: Increases risk from 2 to 6 fold
CVD: Most common cause of death in diabetics
Diabetic neuropathy: Up to 28% of foot ulcers may result in some
form of lower extremity amputation
What are the type of diabetes?
Type 1
Type 2
Maturity onset diabetes of youth (MODY), also called monogenic diabetes – rare form which is distinct from type 1 or type 2
Pancreatic diabetes - Type 3C
“Endocrine Diabetes” (Acromegaly/Cushings)
Malnutrition related diabetes
Gestational diabetes
Definition (blood levels) of diabetes:
Symptoms and random plasma glucose > 11 mmol/l
Fasting plasma glucose > 7 mmol/l
No symptoms - Glucose Tolerance Test (75g glucose) fasting > 7 or 2h value > 11 mmol/l (repeated on 2 occasions) – oral glucose tolerance test
HbA1c of > 48mmol/mol (6.5%)
What are some symptoms of diabetes?
Polyuria
Weightloss
Tiredness/ fatigue
Polydipsia - thirstiness
What is HbA1C?
RBC have lifespan of 3 months – glucose latches onto RBC – measure amount of glucose latched onto Hb – that is the HbA1c
What is the pathogenesis of Type 1 diabetes?
An insulin deficiency disease characterised by loss of beta cells due to autoimmune destruction
Beta cells express antigens of HLA histocompatability
Activates a chronic cell mediated immune process leading to chronic ‘insulitis’
What does failure of insulin secretion do in type 1?
Continued breakdown of liver glycogen
Unrestrained lipolysis and skeletal muscle breakdown providing gluconeogenic precursors
Inappropriate increase in hepatic glucose output and suppression of peripheral glucose uptake
What does the rising glucose concentration result in?
increased urinary glucose losses as renal threshold (10mM) is exceeded
What happens if we fail to treat type 1 diabetics with insulin?
Increase in circulating glucagon (loss of local increases in insulin within the islets leads to removal of inhibition of glucagon release), further increasing glucose
perceived ‘stress’ leads to increased cortisol and adrenaline
progressive catabolic state and increasing levels of ketones
If there is no insulin what do you end up breaking down?
break down fat – lose loads of weight
How can hyperglycaemia occur?
Glucagon increases glucose levels as well – lack of insulin and unrestricted glucagon levels also causes hyperglycaemia
Enter catabolic state
Whats the aetiology of type 2 diabetes?
Progressive hyperglycaemia
and high free fatty acids >
Impaired insulin secretion + Insulin resistance
> Impaired glucose tolerance
> Type 2 diabetes
Whats the difference in type 2 diabetes and normal glucose and insulin profiles?
Normal circumstances someone has breakfast and insulin spikes and glucose level rises and goes back down – always for all meals
Type 2 diabetes – breakfast glucose is high and insulin is not doing a good job – glucose comes down a bit – takes so much longer – starting off at a higher baseline point
What is the natural history of Type 2 diabetes?
Starts with Impaired glucose tolerance (IGT)
Undiagnosed diabetes
Known diabetes
Insulin resistance increases across these stages
Insulin secretion increases from first 2 stages then dips in known diabetes
Fasting glucose increases
Starlings curve of the pancreas
What is type 2 diabetes a consequence of?
insulin resistance and progressive failure of insulin secretion (but insulin levels are always detectable)
Impaired insulin action leads to what in type 2 diabetes?
Reduced muscle and fat uptake after eating
Failure to suppress lipolysis and high circulating FFAs
Abnormally high glucose output after a meal
Low levels of insulin can prevent what?
prevent muscle catabolism and ketogenesis so profound muscle breakdown and gluconeogenesis are restrained and ketone production is rarely excessive
What happens in type 1 ketoacidosis?
Type 1 diabetes no insulin – breakdown free fatty acids and make ketones which are acidic – make you nauseous and blood becomes acidic – get diabetic ketoacidosis – give them insulin and ketones go down and acidosis goes down as well
What happens in type 2 ketoacidosis?
Early on pancreas makes insulin – not gonna break down free fatty acids early on so not necessarily get diabetic ketoacidosis – will get hyperglycaemia –
15 years of type 2 diabetes – will get diabetic ketoacidosis – cant suppress ketones anymore late stage diabetes
Pathophysiology of type 1 diabetes :
Absent insulin secretion : No hepatic insulin effect and no muscle/fat insulin effect
Unrestrained glucose + ketone production > more glucose enters the blood > Hypergylcaemia and raised plasma ketones (leads to glycosuria/ ketonuria) > less glucose enters peripheral tissues > Impaired glucose clearance + muscle fat breakdown
Pathophysiology of type 2 diabetes :
Impaired insulin secretion : hepatic insulin resistance and muscle/fat resistance
Excessive glucose production > more glucose enters the blood > Hypergylcaemia (glycosuria) > less glucose enters peripheral tissues > Impaired glucose clearance
Summary of pathophysiology of type 1 diabetes:
Severe insulin deficiency due to autoimmune destruction of the beta cell (initiated by genetic susceptibility and environmental triggers)
Summary of type 2 diabetes pathophysiology:
Insulin resistance and impaired insulin secretion due to a combination of genetic predisposition and environmental factors (obesity and lack of physical activity)
lipid deposition in liver and pancreas lead to both insulin resistance and impaired insulin secretion
Fats sit on liver and pancreas for type 2 diabetes
High sugar levels toxic to beta cell – pancreas fails cuz its working super hard – rising levels of sugar start to become toxic to beta cells – double whammy
Treatment of type 2 diabetes:
Ideally consists of weight loss and exercise which if substantial will reverse hyperglycaemia
Lifestyle changes are important if they can be achieved
but most with Type 2 diabetes have been making the ‘wrong’ lifestyle choices all their lives and rarely respond to these approaches
At present, management usually consists of medication to control BP, blood glucose and lipids
What are Sulphonylureas (gliclazide, glibenclamide)?
stimulate insulin release by binding to B-cell receptors
Improve glycaemic control (1-2% in HbA1c) at the expense of significant weight gain
Do not prevent the gradual failure of insulin secretion
Can cause hypoglycaemia (occasionally prolonged and fatal, particularly in the elderly and when renal function is impaired)
Use gliclazide in most people
What are Thiazolidinediones (pioglitazone - ACTOS)?
Bind to the nuclear receptor PPAR (peroxisome proliferator-activated receptor)
Activate genes concerned with glucose uptake and utilisation and lipid metabolism
Improve insulin sensitivity
Need insulin for a therapeutic effect
What are glitazones?
relatively rarely used but may be useful in some sub-groups
Increase weight
Increase the risk of heart failure
Increase the risk of fractures
What is GLP-1?
Secreted from L cells of intestine
Stimulates insulin secretion
Suppresses glucagon secretion
Improves insulin sensitivity
Enhances glucose disposal
Slows gastric emptying
Reduces food intake
What happens to native GLP-1?
rapidly degraded by DPP-IV
What drugs Lower glucose Reduce weight and CVD independent of glucose lowering ?
Exenatide(BYETTTA) twice daily
Once weekly exenatide (BYDUREON)
Liraglutide (VICTOZA) once daily
Lixisenatide (LYXUMIA) once daily
Dulaglutide (TRULICITY) once weekly
Semaglatide (OZEMPIC) once weekly
Oral semaglutide (RYBELSUS) daily
DPP-IV inhibitors (oral)
Vildagliptin (GALVUS)
Sitagliptin (JANUVIA)
What do SGL2 inhibitors do?
SGLT2 inhibitors block the reabsorption of glucose in the kidney, increase glucose excretion, and lower blood glucose levels
Agents include: empagliflozin, canagliflozin, dapagliflozin
May have specific benefit in reducing CV mortality
Reduce risk of heart failure readmissions
Reduce risk of heart attacks and kidney disease
Side effects of SGL2 inhibitors
genital thrush, increased risk of euglycaemic ketoacidosis* including in type 2 diabetes, now licensed in type 1 diabetes
DRUGS TO USE
Metformin first line
Sulphonylureas are no longer the second line agents of choice
DPP-IV inhibitors, GLP1 analogues, SGLT-2 inhibitors are replacing sulphonylureas
Use of glitazones rarely used
Why doesn’t DKA occur in Type 2 diabetes?
It is rare because the low insulin levels are sufficient to suppress catabolism and prevent ketogenesis. It can occur if hormones such as adrenaline rise to high levels (eg during an MI)
Why does obesity cause type 2 diabetes?
Obesity (particularly central) impairs insulin action. In those, already insulin resistant due to genetic factors and who have progressive impairment in insulin secretion this brings out diabetes at an early stage.
What is a basal insulin?
Long acting insulin
Examples of basal insulin?
NPH insulin
(INSULATARD and HUMULIN I)
Insulin glargine (100 and 300 U/ml)
(LANTUS and TOUJEO)
Insulin detemir
(LEVEMIR)
Insulin degludec
(TRESIBA)
What are some meal time insulins?
Insulin lispro
Insulin glulisine
EDTA/citrate human insulin
Faster-acting insulin aspart
T1DM features:
Autoimmune condition (β-cell damage) with genetic component
Profound insulin deficiency
T2DM Features:
Insulin resistance
Impaired insulin secretion and progressive β-cell damage but initially continued insulin secretion
Excessive hepatic glucose output
Increased counter-regulatory hormones including glucagon
Whats the modern insulin therapy T1D?
Separation of basal from bolus insulin to mimic physiology
Pre-meal rapid acting boluses adjusted according to pre-meal glucose and carbohydrate content of food to cover meals
Basal insulin should control blood glucose in between meals and particularly during the night
Basal insulin given as either twice daily insulin levemir (basal analogue or once daily degludec) adjusted to maintain fasting blood glucose between 4–7 mmol/L
Quick acting insulin 15 minutes b4 meal so insulin can catch up
Why are insulin analogues important?
have longer action of duration
When do people with T2DM require insulin?
particularly later in the disease course or in individuals with poor glycaemic control on other medications
Long-acting basal insulin are assosicated with what?
lower risk of symptomatic, overall and nocturnal hypoglycaemia
In general, basal insulin is initiated followed by addition of a prandial insulin where necessary
Whats once-daily basal insulin used in?
Just type 2 diabetes
Whats twice daily mix insulin used in?
Type 1 and type 2
What is basal-bolus therapy used in?
Mostly used in type 1 diabetes
Sometimes used in type 2 diabetes
What are the advantages of basal insulin in type 2 diabetes?
Simple for the patient, adjusts insulin themselves, based on fasting glucose measurements
Carries on with oral therapy, combination therapy is common
Less risk of hypoglycaemia at night
What are the disadvantages of basal insulin in type 2 diabetes?
Doesn’t cover meals
Best used with long-acting insulin analogues which are considered expensive.
What are the advantages of pre-mixed insulin in diabetes?
Both basal and prandial components in a single insulin preparation
Can cover insulin requirements through most of the day
What are the disadvantages of pre-mixed insulin in diabetes?
Not physiological
Requires consistent meal and exercise pattern
Increased risk for nocturnal hypoglycaemia
Increased risk for fasting hyperglycaemia if basal component does not last long enough
Often requires accepting higher HbA1c goal of <7.5% or ≤8% (<58 or ≤64 mmol/mol)
What is considered the best treatment for T1DM?
Intensive basal-bolus insulin therapy is considered the best treatment for T1DM
What is the best treatment approach for T2DM?
a treatment approach in which basal insulin is added to oral therapy can improve glycaemic control and reduce hypoglycaemia but bolus insulin for one or two meals is often required
What is level 1 hypoglycaemia?
Alert value
Plasma glucose <3.9 mmol/l (70 mg/dl) and no symptoms
What is level 2 hypoglycaemia?
Serious biochemical
Plasma glucose <3.0 mmol/l
(55 mg/
What is non-severe hypoglycaemia?
Patient has symptoms but can self-treat and cognitive function is mildly impaired