This content was last reviewed in September 2019 by Maria Yiangou, a registered pharmacist in our Health at Hand team.
There are two main types of diabetes:
Type 1: is treated using insulin which is injected under the skin.
Type 2: is usually treated initially with lifestyle and dietary modification. If adequate blood glucose (glycaemic) control isn’t achieved, oral medications, sometimes in combination with insulin may be used.
What is it and what does it do?
Insulin is a naturally occurring hormone in the body. It has many functions, one of the main being to enable the body to use glucose for energy.
The aim of medicinal insulin is to mimic the body’s own natural insulin so that it deals with food and glucose in the same way.
Why do you need to take insulin injections?
To keep the blood glucose levels within certain limits.
Type 1 diabetes
The pancreas doesn’t produce natural insulin and so you would need lifelong insulin medication.
Type 2 diabetes
The pancreas doesn’t produce enough natural insulin and / or the body is unable to use the insulin effectively. If lifestyle changes and oral medications don't achieve adequate glycaemic control, insulin treatment may be started.
How’s insulin used?
Stomach acid and enzymes can destroy insulin medicine so it can’t be taken in tablet form. It needs to be injected.
All types of insulin are given by subcutaneous injection into the upper arm, thighs, buttocks or the abdomen.
It’s important to rotate the site of injection. (See image left) Repeatedly using the same injection site can cause lipohypertrophy. This is where there’s an increase in the amount of fatty tissue in and around the injection site. This can interfere with the ability of the body to absorb the insulin and can cause difficulty calculating the correct doses of insulin.
It’s very important to gain control of blood glucose levels as poor control is associated with an increased risk of the complications associated with diabetes.
Types of insulin medicines
There are four main types of insulin medication:
- Rapid acting insulin: generally acts within five to ten minutes and can last up to four hours. This insulin is designed to cope with a sudden influx of glucose following a meal and is referred to as bolus insulin.
- Short acting insulin: generally acts within 30 minutes of the injection and can last up to six hours
- Intermediate acting insulin: generally acts within two hours of injecting and can last up to 18-24 hours.
- Long acting insulin: generally acts within one to three hours of injecting and can last up to 12-24 hours and in some cases up to 48hours. These medicines are designed to give a constant background amount of insulin throughout the day so they closely mimic the body’s own natural background insulin. This type of insulin is known as basal insulin.
There are many different names and brands available on the market so the table below may help to identify your particular insulin.
The table below is taken from the Chemist and Druggist CPD module ‘Managing Type 1 diabetes’ 09 Oct 2013.
The effect of insulin varies according to the individual. Your doctor or diabetes specialist will use one type of insulin or a combination of different types to suit your particular needs. They’ll also choose the insulin pen or device on this basis.
It may take time to find the insulin, the insulin device and pen needles that best suit you so it’s important to work closely with your specialist.
Once your blood glucose levels have stabilised and you’ve found the insulin treatment that suits you then you’ll feel more in control.
You’ll be issued with one or two insulin passport cards. These are designed to make sure that medication errors don’t occur as the packaging can be very similar. Always check the insulin when collecting from the pharmacy and just before injecting it.
Insulin is available in vials, 3ml cartridges which fit into a reusable pen device or in pre-filled pen devices. The cartridges differ slightly in shape so they’re specific for the pen device.
Insulin cartridges and pre-filled pens should be stored in the original box, in the fridge (ideally two to eight degrees centigrade) and protected from sunlight. Once in use, the cartridge or the pre-filled pen should be stored at room temperature away from extreme heat and sunlight.
Remember your insulin requirements can change due to the type of meal you’ve had and if you’ve been exercising. You may need more insulin than usual if you have an infection, are under stress, have had an accident or have had surgery and during puberty. Consult your doctor or your diabetes nurse specialist if you’re concerned.
You need to continue using your insulin when you’re feeling unwell even if you’re not eating. Remember to drink lots of fluids, replace food with milkshakes or other carbohydrate drinks if needed and keep testing your blood glucose and your ketone levels. If you start vomiting seek immediate medical attention.
If you’re due to have elective surgery you should ensure that your doctor and the particular nurse looking after you in hospital are aware of your condition so that they can take this into consideration and ensure you know what to expect.
If you’re travelling abroad it’s a good idea to take your insulin supplies with you in your hand luggage in a suitable insulated bag or an open necked vacuum flask. Never put it in the hold because the insulin can freeze and make it ineffective. Please note that it is advisable to obtain a letter from your doctor stating that you need to carry these medications, including needles, on your flights.
The manufacturer of your insulin will provide you with guidance on this matter as well as informing you of overseas availability. It’s worth noting that the same insulin available abroad may be under a different name and strength such as 40 units/ml or 500 units/ml as opposed to the standard 100units/ml available in the UK. This may mean you’ll need to change the amount you inject to receive the same dose. Always check the strength of the insulin.
If you can’t obtain adequate control of your blood glucose levels using the insulin devices we’ve just told you about then your doctor may prescribe rapid acting insulin via an insulin pump.
An insulin pump is a small device which delivers a constant amount of rapid acting insulin.
The amount of insulin delivered can be adjusted by pressing the buttons on the device. It’s mainly used by children but some adults with type 1 diabetes find it useful. The advantage is that you can avoid multiple injections.
If you’re using this type of device your doctor, diabetes nurse specialist or your dietician will train you how to adjust your diet and alter the flow of insulin according to your needs.
Glucagon is available as a GlucaGen Hypokit. It’s a hormone used to treat hypoglycaemia, particularly insulin-induced hypoglycaemia, when you can’t swallow or if you’re unconscious during a hypoglycaemic event.
Very few people need this medication. It can be stored for three years in the fridge or 18 months at room temperature but never in or near the freezer. The patient information leaflet explains how to use it.
Medicines used to treat type 2 diabetes
Medications used in the management of type 2 diabetes include:
- Sulfonylureas group - glibenclamide, gliclazide, glimepiride, glipizide and tolbutamide,
- Pioglitazone (Actos)
- DPP-4inhibitors - saxagliptin, sitagliptin, linagliptin and vidagliptin.
- GLP1 agonist - exenatide (Byetta), liraglutide(Victoza) and lixisenatide (Lyxumia)
- Metiglinides/Glynides- repaglinide, nateglinide
If you’d like detailed information on these medications and insulin please click on the sections below.
Factors influencing the choice of medication
The choice of medication used takes into account a number of different factors including your weight (some medications can promote weight gain, whilst others can reduce weight), your job (due to the risk of suffering ’hypos’ with certain medications), side effects and pre-existing medical conditions (including kidney disease).