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INSULIN - a patient's guide
Natalie Gauld and Dale Griffiths - Pharmacy Educators
Very fast acting:
Contains Insulin Lispro. Starts acting in 15 minutes.
Lasts 2 to 5 hours.
Humalog
Fast acting:
Contains Soluble Insulin (Neutral). Starts acting in 30
minutes. Most effect in 1 to 3 hours. Lasts 6 to 8 hours.
Actrapid
Humulin R
Medium acting:
Contains Isophane Insulin or Insulin Zinc Suspension.
Usually starts acting in 2 hours, most effect in 4 to 12
hours and last up to 24 hours.
Humulin L
Humulin N
Monotard
Long acting:
Contains Insulin Zinc Suspension (Crystalline). Usually
starts acting in about 4 hours, most effect around 10 to
20 hours and last up to 36 hours.
Humulin U
Ultratard
Mixed long and short acting insulin (biphasic):
Neutral and Isophane Insulin
Humulin 80/20 or 70/30
Mixtard 30/70 or 50/50
Penmix 10, 20, 30, 40, or 50
The time effect of insulin and length of action can vary
from person to person, and can also depend on where the
injection was given, temperature, physical activity and
blood supply. The above figures are only a very rough guide.
Similar forms of insulin may have matching label colours.
Use:
Insulin is important to our health because it allows the
energy from our food to be used by the body. Food is made
into glucose which goes into the bloodstream and travels
around the body. Insulin controls the level of glucose in
the blood, helping it to act as a fuel for our body. Without
insulin glucose does not leave the bloodstream, but instead
accumulates in the blood, causing major problems. Before
insulin was available, the insulin-dependant diabetes (Type
1) was fatal.
A diabetic does not have enough insulin (or is resistant
to it), so needs to use insulin injections to help the food
he or she eats to be used by the body as fuel. Usually the
aim is to keep blood glucose between 4 and 10 mmol/L (72-180mg/dL)
during the day, or as you and your doctor decide. Good control
means that you have less risk of the long-term effects of
high blood glucose, such as damage to the eyes and kidneys.
Good control of diabetes has been convincingly shown to
reduce these complications.
Insulin is usually given by injection just under the skin
(sub-cutaneous) in the following areas: upper arms, thighs,
buttocks or abdomen. If the insulin is given by mouth it
will not work because enzymes in the stomach and intestine
make it inactive. Where you inject the insulin can affect
how fast it works; e.g. injecting under the skin around
the abdominal (stomach) area is more evenly available. Increased
blood flow in an area being injected may also make the insulin
work quicker, e.g. strenuous exercise or a hot bath. For
dialysis patients, insulin can be given in the dialysis
fluid.
It is common to use two different forms of insulin - a
medium-acting one and a fast-acting one, these are often
mixed together. Some products such as Penmix and Mixtard
contain a mixture of medium-acting and fast-acting. This
can save mixing them yourself.
Insulin lispro is a more recent type of insulin that works
very quickly. It can be given up to 15 minutes before a
meal, or after a meal has begun. For small children with
changeable appetites the injection can be given during or
straight after a meal; this means you can give the right
amount of insulin for how much they have eaten. The faster
action means that you have less risk if a meal is delayed
as you can inject just before the meal (when it arrives)
rather than 30 minutes before.
Cautions:
Do not use insulin if the blood glucose is too low (hypoglycaemic).
Do not use in people who are not diabetic.
Changing from one insulin to another, or to do more intensive
treatment may change the usual warning signs of a "hypo".
Only do this under a doctor's supervision and take blood
glucose tests frequently.
The amount of insulin needed will usually increase with
illness, stress and during operations. Extra monitoring
and extra care with food is needed at these times.
The amount of insulin needed will reduce with liver or
kidney damage.
Side effects:
Skin reaction where the insulin is injected (e.g. red
itchy skin) but this doesn't usually last.
Fat buildup if the injection site is not rotated (which
can then make insulin absorption from that spot changeable).
Extremely uncommon: allergy to insulin.
Hypo
If too much insulin is given, or less food is eaten than
usual, or food is delayed, or there is unexpected exercise
a "hypo" or hypoglycaemic attack may happen. The usual symptoms
can include pins and needles around the mouth, sweating,
shakes, feeling the heart beating fast and hunger. Sugar
must be taken immediately, e.g. glucose tablets, jellybeans,
barley sugars or a glass of lemonade. Then it is important
to have food with carbohydrates to stop it happening again.
If a hypo is not treated immediately the person can become
unconscious. Do not drive while having a hypo.
There may be other side effects, so if you have any unexpected
symptoms while taking this medicine, tell your doctor or
pharmacist.
Pregnancy:
In pregnancy very good control of blood glucose is important
for having a healthy baby, so you are best to talk to your
doctor if you are planning to become pregnant. You will
probably need less insulin than usual in the first trimester
and more in the second and third trimesters. There can be
an increased chance of "hypos" during the night.
Interactions:
Some beta-blockers (e.g. propranolol) may make the symptoms
of hypoglycaemia less obvious.
Alcohol may enhance the effect of insulin, and may make
it work longer (increasing the risk of a hypo); it is important
not to have alcohol without eating some food.
ACE inhibitors may reduce the amount of insulin needed.
Aspirin.
Oral contraceptives can have a small effect.
Thiazide diuretics, e.g. bendrofluazide.
Corticosteroids e.g. prednisone or prednisolone.
Thyroid hormones.
Diltiazem and other calcium channel blockers.
Cold remedies containing a decongestant.
Liquid medicines often contain sugar and/or alcohol.
Check with your doctor or pharmacist about a possible
interaction if other medicines are prescribed for you.
Patient information:
Follow the instructions on the label of the medicine or
as directed by your doctor.
Keep your extra stocks of insulin refrigerated.
The insulin vial you are using can be left at room temperature.
If you will soon be changing to a new vial, the new vial
can be removed from the refrigerator so that it can come
up to room temperature before you need to inject it.
Most insulin can be kept at room temperature (up to 25¬?
C) for up to a month. Discard any remaining insulin in a
vial four weeks after first using.
Insulin must not be frozen; if it is frozen do not thaw
then use, throw it away.
Regular blood glucose monitoring is important and will
give you control over your diabetes.
Do not miss meals or snacks.
Always carry something sugary with you (e.g. glucose tablets,
jellybeans) in case of a "hypo" or hypoglycaemic incident.
If you get sick your insulin needs might change. It is
important you check your blood glucose regularly, and you
should not stop your insulin. Your doctor or diabetes nurse
should be able to advise you on what to do if you become
ill.
Frequent high blood glucose will cause long-term problems
such as eye and kidney problems, so should be avoided.
If you are thinking of getting pregnant, talk to your
doctor first. It is best to get your diabetes very well
controlled before conception.
Rotate your injection sites.
Check blood glucose levels before driving and every couple
of hours during long journeys. It is important to avoid
a hypo while driving.
Wash your hands well before drawing up the insulin and
injecting the dose.
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