INSULIN AND TYPE 1 DIABETES
KEY POINTS
All people with Type 1 diabetes must take insulin medication.
Insulin is a naturally occurring body hormone.
Taking insulin by injection is designed to try to mimic the way your body would produce its own insulin (if you didn’t have diabetes).
There are a number of different types of insulin that vary in the length of time they are absorbed into and continue to act in your body.
When you are starting on insulin you will get lots of help and support from your local specialist diabetes service.
It is essential to have a variety of skills to manage being on insulin. There are specialist diabetes nurses available to help you gain these skills.
Your insulin therapy can be tailored to fit with your own particular lifestyle. If you are newly diagnosed with Type 1 diabetes or you are thinking about making a change to your current insulin, always work closely with your specialist diabetes team.
When you have Type 1 diabetes, your body can’t produce its own insulin. Insulin is a body hormone that needs to circulate in your blood stream to do its job properly. If you don’t have enough insulin your body is unable to use or store glucose properly. When you have Type 1 diabetes, you need to take your insulin by injection (under the skin).
Many people wonder why it is not possible to take insulin as a tablet. Insulin cannot be taken as a tablet, because when it is, it gets broken down in your gut and ceases to be insulin.
In some countries research has been done into giving insulin in an inhaled form (similar to an inhaler used for asthma drugs). This has been somewhat successful, but there are still problems with this system and it is not widely available commercially.
Most people feel very anxious when they first find out that they need to start taking insulin. But with support, this initial hurdle is manageable.
Nowadays the insulin needles are so short and fine that nearly everyone finds that their insulin injections are far more comfortable than finger pricks. Insulin injections go just under your skin and not into a vein.
People often feel a lot more well and energetic once they get established on insulin. They have often been short of their own insulin for a very long time and this has made them feel unwell, tired, and often prone to all sorts of infections.
What is insulin and where does it come from?
Insulin is a hormone. It occurs naturally in the human body. The insulin that you get from the chemist is what is called ‘human insulin’. Many years ago, insulin for injection came from pigs or cows and was called ‘porcine insulin’ or ‘bovine insulin’.
Human insulin is manufactured in the laboratory. It is made by cell organisms (e.g., yeast or Ecoli cells) that have had the human gene for making insulin spliced into them. These cells then busily make insulin. This human insulin is a very safe product to take and there have been no instances of insulin becoming contaminated with anything harmful.
What tests do I have to find out how my diabetes management is going?
Managing your diabetes means managing a number of factors in your life. You can get a good idea of how effective this management is by the results of some of the laboratory tests you have done.
A number of laboratory tests are currently available in New Zealand to measure your blood glucose levels.
Blood (or plasma) glucose level
This measures how much glucose you have in your blood at the time the test is taken. A person without diabetes would nearly always have a blood glucose level somewhere between 4 – 7.5 mmol (a ‘normal’ blood glucose level).
Blood glucose series
This is a series of three tests for blood glucose levels. There are different ways of doing this kind of test but a common way is as follows:
Day one: Have your normal breakfast and medication or insulin. Have your normal mid-morning snack (if you have one) and go to the laboratory for the first blood glucose test before your lunch. Have your usual lunch (and medication or insulin if you take it), then go back to the laboratory 2 hours after lunch and have your second blood glucose test taken. Have your normal food and medication or insulin for the rest of the day.
Day two: Have no insulin, medication or food when you wake up in the morning. Go to the laboratory as soon as you can and have your third blood glucose test taken. Once this is done, have your medication or insulin and your breakfast. Your blood glucose series is now complete.
The aim of such a series is to get a ‘picture’ of your usual blood glucose levels on a close to normal day.
What are healthy levels for a blood glucose series?
Everybody will have different target levels depending on lots of individual factors. You and your doctor need to work out realistic and safe target levels for you. A general guide to target levels for a blood glucose series is:
Pre-lunch between 4.5 – 7.8mmol
2 hours after lunch between 4.5 – 8.5mmol
First thing in the morning(fasting) between 4 – 6mmol
HbA1c level (also called glycosalated haemaglobin level)
This measures your average blood glucose over the past 4 – 6 weeks. It measures how much glucose is stuck onto your red blood cells. Red blood cells have a life span of about 120 days and so the test gives a good indication of what your overall blood glucose levels have been through that time.
Most diabetes specialists and GPs have a lot of confidence in this test and will use it to help show you how you are going with your blood glucose management.
HbA1c levels are measured as millimoles per mol (mmol/mol) and represent the average of your blood glucose levels over the previous 6 weeks. The HbA1c level is not directly equivalent to blood glucose levels.
What are healthy HbA1c levels?
Once again, target HbA1c levels will vary from person to person. Work out a safe target HbA1c for you with your doctor. A general range for HbA1c levels is:
People without diabetes have an HBA1c of less than 40mmol/mol
Target levels for most people with diabetes is 50 – 55 mmol/mol. The lower the better as long as hypoglycaemia is minimised.
Levels of 56 – 64 mmol/mol may need some increase or adjustment in treatment depending on circumstances
Levels of 65 – 90 mmol/mol indicates your blood glucose levels are much too high
Levels above 90mmol/mol indicates your blood sugars are extremely high
Note: if you are taking insulin and your HbA1c level is less than 40 mmol/mol this almost certainly indicates that you are having lots of low blood glucose levels. Having HbA1c levels this low is not safe when you are taking insulin.
Fructosamine level
This measures your average blood glucose levels over the previous 2 weeks. This measure is not as commonly used in New Zealand as HbA1c levels. This is because many people feel HbA1c levels tend to be more accurate and reliable.
Some diabetes services use fructosamine as a useful measure for women who are pregnant. Because insulin needs (and consequently blood glucose levels) change so rapidly during pregnancy, some services prefer to use fructosamine rather than HbA1c, as it looks back over a shorter time and therefore may reflect rapid changes more effectively.
What is a healthy fructosamine level?
If you are not pregnant the target healthy level is less than 300. When you are pregnant the target healthy level is less than 200.
What laboratory tests are done to measure my blood fats (Cholesterol or Lipid Levels)?
The level of cholesterol or fats in your blood is measured by a test called a blood lipid profile. This measures the level of a number of different fats in your blood.
The fats that are measured are:
Total cholesterol
HDL Cholesterol (high density lipoproteins)
LDL Cholesterol (low density lipoproteins
Triglycerides
Healthy levels of these fats are:
Total cholesterol less than or equal to 5.0mmol
HDL Cholesterol greater than 1.0mmol
LDL Cholesterol less than 2.5mmol
Triglycerides less than 2.0mmol
What other lab tests am I likely to have done?
A test you will have done regularly (it should be done at least once a year) is your ‘microalbuminuria’ level. This is a laboratory test that is done on a sample of urine. It involves checking for microscopic amounts of protein in your urine.
Small amounts of protein leaking out into your urine is an early sign that your kidneys are developing damage from diabetes (diabetic nephropathy). You can tell if you have kidney damage and also if it is getting worse or not from the amount of protein leaking.
Your microalbuminuria levels should be plotted on a graph over time. Hopefully, these levels will stay low, but if they are rising then this shows there is a problem happening with your kidneys. It is best if your microalbuminuria levels are less than 2.
If your test comes back with raised microscopic protein levels your doctor may ask for you to have the test again. This is because, sometimes, your microalbuminuria levels can be up if you have an infection or even if you have been exercising hard. If they are up for this reason, this is just temporary and not a problem. Repeating the test helps to eliminate a ‘false positive’ for either of these reasons.
You may also have your thyroid hormone levels tested (especially if you have Type 1 diabetes). Checking your thyroid function involves having a sample of blood taken at the laboratory. Some diabetes clinics will check your thyroid function on a fairly regular basis. Your doctor will discuss the results with you.