Week 10 - Diabetes Flashcards
where is glycolysis carried out?
liver
what is the role of glycolysis?
extract energy from glucose
what is gluconeognesis?
synthesis of glucose from nonsugar precursors
where does gluconeogenesis mainly occur?
liver
and to a lesser extent the cortex of the kidney
what is glycogenolysis?
when glycogen breaks down into glucose
where does glycogenolysis occur?
hepatocytes and myocytes
what enzymes regulate glycogenolysis?
phosphorylase kinase and glycogen phosphorylase.
what is glycogenesis?
process of storing excess glucose as glycogen
which cells produce endocrine hormones?
islets of langerhans
pancreas
which cells produce glucagon?
alpha cells
what do alpha cells produce? (pancreas)
glucagon
which cells produce insulin?
beta cells
what do beta cells produce? (pancreas)
insulin
what do gamma cells produce? (pancreas)
pancreatic polypeptide
where are pancreatic polypeptides produced?
gamma cells
where are somatostatins produced?
delta cells
what do delta cells produce? (pancreas)
somatostatin
what do E-cells produce? (pancreas)
ghrelin
where is ghrelin produced?
E-cells
what is the function of glucagon?
increase blood sugar levels
what is the function of insulin?
decreases blood sugar levels
what is the function of somatostanins?
inhibits glucagon and insulin release
what is the function of pancreatic polypeptides?
regulates endocrine and exocrine secretion activity
list the microvascular complications that occur with diabetes?
retinopathy
nephropathy
neuropathy
what is non-proliferative retinopathy?
development of microaneurysms, venous loops, retinal hemorrhages, exudates (fluid that leaks out of blood vessels into nearby tissues).
what is proliferative retinopathy?
presence of new blood vessels, with or without vitreous hemorrhage. It is a progression of nonproliferative retinopathy.
what is seen on a fundoscopy of background retinopathy?
dots = microaneurysms
blots = small intraretinal haemorrhage
hard exudates = lipid
what is seen on a fundoscopy of pre-proliferative retinopathy?
cotton wool spots = ischaemia
intraretinal microvascular abnormalities
what is seen on a fundoscopy of proliferative retinopathy?
new vessel formation = very friable and have a high tendency to bleed
what is nephropathy?
Progressive deterioration in renal function resulting in end-stage renal disease, particularly glomerular sclerosis
how does diabetic nephropathy occur?
- Increased glomerular capillary flow with urine containing high glucose levels results in increased extracellular matrix production and endothelial damage
- The vascular damage to the glomerulus causes increased permeability to macromolecules, results in proteinuria (excessive protein loss in the urine). Specifically microalbuminuria, which is often the first sign of CKD.
- Causes mesangial expansion and interstitial sclerosis which can cause glomerular sclerosis.
- Also nonaluminium renal impairment due to unresolved episodes of acute kidney injury
what tests can be done to diagnose diabetic nephropathy?
- ARC (albumin to creatine ratio)
>3mg/mol- EGFR (glomerular filtration rate)
<60
BP
- EGFR (glomerular filtration rate)
what is neuropathy?
Heterogeneous condition associated with nerve pathology.
The condition is classified according to the nerves affected and includes focal, diffuse, sensory, motor, and autonomic neuropathy.
how does diabetic neuropathy occur?
- Diabetes is associated with dyslipidemia, hyperglycemia, and low insulin and growth factor abnormalities.
- These abnormalities are associated with glycation of blood vessels and nerves which causes structural nerve damage including: segmental demyelination, axonal atrophy and loss, and progressive demyelination.
- These effects causes a decrease in nerve sensitisation and also affect ANS function -> neuropathy.
- In addition, autoimmunity may affect nerve structure.
- Poor blood supply and nerve damage can also lead to the formation of ulcers seen often on diabetic’s feet.
what are the macrovascular complications of diabetes?
- Primarily diseases of the coronary arteries, peripheral arteries and cerebrovascular.
- Early macrovascular disease is associated with atherosclerotic plaque in the vasculature supplying blood to the heart, brain, limbs and other organs.
- Late stages of macrovascular disease involve complete obstruction of these vessels, which can increase the risk of MI, stroke, claudication and gangrene.
- Peripheral ischaemia causes poor skin healing and diabetic foot ulcers
how do macrovacular complications of diabetes occur?
Result from hyperglycemia, excess free fatty acid and insulin resistance -> increases oxidative stress, protein kinase activation and activation of glycine end products which act on the endothelium to cause:
* Increased vasoconstriction which causes hypertension and vascular smooth muscle cell growth
* Increased inflammation
* Thrombosis, hypercoagulation and platelet activation and decreased fibrinolysis
what is type 1 diabetes?
a condition where the pancreas stops being able to produce adequate insulin
Without insulin, the cells of the body cannot absorb glucose from the blood as use it as fuel.
The glucose levels in the blood keep rising, causing hyperglycaemia
what is thought to be involved in the onset of T1DM?
cold weather
viruses e.g. enteroviruses and coxsackie B
early diet - less common in breastfeeding
what age does T1DM usually present?
10-14
but can appear anytime before 40
what are the presenting symptoms of T1DM?
○ Polyuria (excessive urine)
○ Polydipsia (excessive thirst)
○ Weight loss (mainly through dehydration
May also present with diabetic ketoacidosis
what are the 3 key features of diabetic ketoacidosis?
Ketoacidosis
Dehydration
Potassium imbalance
why do each of the 3 symptoms of diabetic ketoacidosis occur?
ketoacidosis = liver produce ketones to fuel body. initially kidneys produce bicarb to counteract ketone acids but over time the bicarb is used up .: blood is acidic
dehydration = hyperglycaemia overwhelms the kidneys, glucose leaks into urine, water is drawn into urine by glucose .: polyuria .: dehydration
potassium imbalance = insulin normally drives K+ into cells .: no inulin = no K+ in cells .: high serum K+ .: total body K+ is low as its not stored in cells .: hypokalaemia which can lead to arrhythmias
what is the main cause of T2DM?
overweight and obesity, sedentary lifestyle and increased consumption of unhealthy diets containing high levels of red meat and processed meat, refined grains and sugar-sweetened beverages.
what are some non-modifiable factors of developing T2DM?
aging
black-african/carribean and south asian
family history
what are the presenting features of T2DM?
- Tiredness
- Polyuria and polydipsia (frequent urination and excessive thirst)
- Unintentional weight loss
- Opportunistic infections (e.g. oral thrush)
- Slow wound healing
Glucose in urine (on a dipstick)
how does T2DM occur?
Repeated exposure to glucose and insulin makes peripheral tissue resistant to the effects of insulin. More and more insulin is required to stimulate the cells to take up and use glucose (blood sugar).
Over time, the pancreas becomes fatigued and damaged by producing so much insulin, and the insulin output is reduced.
what is the defenition of hypoglycaemia?
Plasma glucose of <3.0mmol/L
what is the treatment of hypoglycaemia when the patient is conscious?
○ Administer glucose gel by mouth (e.g. GlucoGel)
○ Repeat capillary blood glucose after 10-15 minutes and if the patient is still hypoglycaemic, repeat administration of glucose gel a further 2-3 times
When the patient is fully alert, provide a longer-acting carbohydrate for the patient to eat (e.g. toast)
what is the treatment of hypoglycaemia when the patient is unconscious?
○ Administer intravenous glucose (e.g. 150-160 ml of 10% glucose)
○ If the patient then regains consciousness, switch to using oral glucose as above
If IV access is not able to be established rapidly, administer glucagon 1mg via the intramuscular or subcutaneous route. Glucagon stimulates the conversion of stored glycogen within the liver into glucose. As a result, glucagon is ineffective in patients with depleted glycogen stores (e.g. elderly patients with poor oral intake and patients with eating disorders)
how do you remember the treatment of DKA?
FIGPICK
* Fluids - IV fluid resuscitation with normal saline (1 litre in first hour, followed by 1 litre every 2 hours) * Insulin - fixed rate insulin infusion (e.g. Actrapid at 0.1 units/kg/hour) * Glucose - closely monitor blood glucose and add a glucose infusion when it is less than 14 mmol/L * Potassium - add potassium to IV fluids and monitor closely (e.g. every hour initially) * Infection - treat underlying triggers * Chart - chart fluid balance * Ketones - monitor blood ketones, pH and bicarbonate