L17 - Diabetes Flashcards
Where is insulin produced and what roles does it have?
- produced in the pancreas
roles:
- transport glucose from blood supply into fat and muscle cells where it can be used for energy
- stops liver gluconeogenesis once the level of glucose in the blood is high enough
What is the effect of diet on blood glucose?
- high sugar foods cause short but high increase in glucose levels
- fibre in the diet slows absorption so high fibre diet slows the spike in glucose
- low GI (glycaemic index) foods have a gradual increase in blood glucose over a longer time
What are the effects of lack of insulin?
- low cellular glucose intake
- reduced fuel = metabolic issues = tired because insufficient energy
- high blood glucose - can damage vessels and increase risk of cardiovascular disease
How does insulin work?
- secreted into portal (liver) circulation
- insulin binds to transporter
- increased GLUT4 synthesis
- transports glucose into the cell
What are the types of diabetes?
type I - insulin dependent diabetes - due to too little insulin - pancreas not producing enough - genetic factor type 2: - insulin independent - cellular desensitisation to insulin - environmental influence
others:
secondary diabetes due to damage to the pancreas
gestational diabetes
What is the treatment for type 1 diabetes?
replace the insulin
- patient must take daily injections of insulin to survive
Why does insulin need to be injected?
because insulin has a bioavailability of 0% - it gets broken down by the stomach acid and emzymes in the GIT
What is the difference between intravenous and subcutaneous administration of insulin in type 1 diabetes?
- IV usually only used in emergency situation (first discover diabetic)
- subcutaneous reaches a lower peak but it is longer. less painful injections and easier to self administer
How do diabetics know they need insulin?
use a Glucometer (glucose meter)
recommendations: 5.0-7.2 mmol/L before meals, less than 10 mmol/L after meals
What are the best sites to inject insulin?
fast absorption areas = arms + abdomen because large blood flow slowed by abdominal fat
slowest absorption areas = thighs and buttocks due to fat (increased absorption by exercise)
need to change sites regularly otherwise can develop hard lumps which reduce absorption
What are the types of insulin for type 1 diabetes?
rapid acting (Novo Rapid)
- acts immediately
- but short duration (1-2 hours)
- used straight before or after a meal
- for random adjustments throughout the day
short acting (Actrapid)
- acts after 30 minutes
- lasts up to 4 hours
- used for main meals of the day
intermediate/long acting (Humulin NPH, protaphane)
- acts after an hour
- lasts all day
- used for patients with strict lifestyle and diet who dont want to use medication all day
- used for once or twice daily dosing
What are the factors affecting selection of ideal insulin protocol?
- patient understanding of need for insulin
- patient willingness to self-inject
- patient fear of diabetic complications
- patient preference for some dietary flexibility
What is treatment plan 1: minimum choice protocol?
- patient wants minimal participation in decision making
- patient prefers set diet and exercise schedules with set meal and snack times (meals with low GI foods + little/no snacking)
- usually prefers insulin protocol with little flexibility
- good stability without hypos
- because of inflexibility, “cheating” cannot be compensated
What is treatment plan 2: tight protocol?
- patient wants to maintain optimal blood glucose levels at all times
- wants to be proactive and self-managing
- 2 part protocol: maintain basal insulin level + add meal/snack insulin as required
- patient continuously monitors and adjusts own requirements
- greater probability of hypoglycaemia
What factors is type 2 diabetes associated with?
- obesity
- lack of exercise
- poor diet
Why is the insulin receptor resistant to insulin (low affinity) when blood glucose levels are high?
- when high insulin in the blood, receptor = low affinity binding
- this is to conserve the brain’s glucose supply by preventing uptake of excessive glucose into muscles
- reducing insulin and glucose levels would increase functioning of the receptor
What are the treatment options for type 2 diabetes?
- lifestyle changes (Green script)
- glucose lowering drugs
treatment may also include drugs which: - reduce blood pressure (antihypertensives)
- reduce lipid levels (statins)
- reduce risk of cardiovascular disease (e.g. aspirin)
What is the Green script?
health lifestyle
- increase exercise
- nutritional advice
- avoid sugary foods
- high protein diet over carbohydrates
- low GI carbs
- reduce fried food (i.e. bad fats)
- reduce alcohol
What is the first line therapy for type 2 diabetes treatment?
Metformin
- doesnt directly reduce glucose levels
- promotes amount of glucose entering the cell
- well-tolerated = does not cause hypoglycaemia
What effects does Metformin have?
- decreases glucose absorption in the GIT
less glucose reaching bloodstream = less insulin released from pancreas - decreases glucose production in the liver (gluconeogenesis)
- increases insulin-mediated glucose uptake in skeletal muscle
because less insulin being released from pancreas
these overall leads to decreased blood glucose
What are the pharmacokinetics of metformin?
- take with food to delay absorption = better tolerated + less side effects
- bioavailability of 50-60%
- plasma life ~6 hours
- no hepatic metabolism so excreted unchanged
What are the side effects of metformin?
- diarrhoea and abdominal discomfort (may be due to not absorbing glucose)
- contraindicated in patients with renal disease (less excretion = higher plasma levels = increased toxicity)
- may cause lactic acidosis (build up of lactate in muscles) due to low levels of glucose
can be reduced by reducing the dose
In what situations can the risk of hypoglycaemia increase?
- malnutrition because insufficient carbs in diet
- irregular meals
- lactation and pregnancy because increased energy demand + need for glucose
- alcohol causes increased insulin secretion = decreases blood glucose concentration
What are the factors that increase the risk of hyperglycaemia?
- inconsistent meal times (large meals)
- high sugar diet
- under medicating or forgetting to take medications
- illness
- stress: survival mechanism = increase glucose to fuel brain and muscles
What is the Protocol for managing diabetes during illness (cold or flu)?
- check blood glucose every 4 hours
- eat/drink 45-50 grams carbohydrates every 4 hours
- do not stop insulin (use rapid insulin to drop glucose levels to <10 mmol/L
- if necessary, stop taking oral medication
- consult doctor/nurse
- if blood glucose is high (>13 mmol/L) check for ketones in urine
Why is it important to treat diabetes and manage hyperglycaemia?
short term
- prevent symptoms of hyperglycaemia + prevents hypoglycaemia
- allow for near normal life
long term
- prevent vascular complications:
- increased blood sugar damages the cells in blood vessels
- small vessels are more susceptible to damage (retinal damage, kidney disease, hypertension = heart disease risk, brain = risk of stroke)
