Insulin Treatment Flashcards
What are the actions of low levels of insulin (basal insulin) in the fasting state?
1) Allow controlled production of glucose (and ketones) by the liver
2) Stop blood glucose rising day to day
3) Minimal uptake of glucose into muscle/fat
What are the actions of high levels of insulin after eating?
1) Completely suppress glucose and ketone production by liver
2) Promote glucose uptake into muscle and fat from liver in the form of glycogen
Why is basal insulin required?
- To balance whatever glucose the liver is making
- Cells need insulin to take up glucose
How quickly does the rise in glucose occur after a meal?
Within 10 minutes
How does insulin reach the liver?
It goes from the pancreas through the hepatic portal system to the liver
How is exogenous insulin different from endogenous insulin?
1) Injectable
2) Loss of portal:peripheral gradient - injected into systemic system not portal system
3) Loss of C-peptide
4) Not controlled endogenously so can’t adjust dose once injected and narrow therapeutic index
5) Weight gain (more effect in s/c tissue, stop losing calories in urine)
6) Allergies
What does the narrow therapeutic index of insulin mean?
- The chance of getting the s/c dose completely correct are low
- Main risk = too much insulin
Why does physiological weight gain occur from controlling diabetes?
- In uncontrolled diabetes, lose 500-600 kcal/day in urine in the form of glucose
- So if start insulin and don’t change diet or exercise then you bring your weight back to what you would have been without diabetes
What are the rapid-acting insulins (prandial)?
1) Monomeric (Novorapid, Humalog)
2) Regular
Describe how monomeric insulin acts
- Starts having its effect at 15-20 minutes
- Peak at 60-70 minutes
- Lasts 2-3 hours
When do you take monomeric insulin?
20 minutes before meal
Describe how regular insulin acts?
- Starts having effect at 30 minutes
- Peak at 2-3 hours
- Lasts 4-6 hours
When do you take regular insulin?
30 minutes before meal
What are the long-acting insulins (basal)?
1) Intermediate (NPH)
2) Peakless e.g. detemir (attached to fatty acid), glargine (attached to acid, stings a bit)
Describe intermediate insulin
- Starts having effect at 3-4 hours
- Peak at 5-6 hours
- Lasts for 10-12 hours
When is intermediate insulin used and what is the problem with it?
- Used at night time
- Problem with night time hypoglycaemia
Describe mixed (biphasic) insulin
- A mixture of rapid and long-acting insulin (intermediate/peakless)in a stated proportion
- Two injections a day for 24h cover
What does the molecular size of the insulin correlate with?
The rate of absorption from s/c injection sites
Describe how the rate at which insulin acts can be changed?
- Insulin normally acts as a hexamer with a zinc molecule, but to act it needs to break down into monomers
- Can alter the rate at which the hexamer breaks down into monomers to change how fast it acts
- Can do this by injecting monomers or binding the hexamers together or to other agents
What is the onset and duration of peakless insulin?
Onset = 90 minutes Duration = 14-24h
When are rapid-acting insulins taken?
Around meal times