Common questions about biphasic insulin - Brand names: Humalog Mix 25, Humalog Mix 50, Humulin M3, NovoMix 30

Insulin is a hormone made in your pancreas (a gland behind the stomach). When food is digested and enters your bloodstream, insulin moves glucose out of your blood and into cells, where it's broken down to produce energy.

When your pancreas is working properly it's constantly making small amounts of insulin and releases more insulin when your blood glucose levels rise after eating.

When you have diabetes, your body does not make enough insulin, or the insulin that it makes does not work properly. You need to inject insulin to replace what your body cannot produce.

There are several different types of insulin. Rapid-acting insulin and short-acting insulin work quickly and you take them before meals. Intermediate-acting insulin acts slowly to produce a long and steady glucose-lowering effect. Long-acting insulin also acts slowly, and works for longer than intermediate-acting insulin.

Biphasic insulin is a mixture of a rapid-acting or short-acting insulin and an intermediate-acting insulin in fixed proportions. For example, Humulin M3 contains 30% short-acting insulin and 70% intermediate-acting insulin.

It's usually injected twice a day, to give you a higher level of insulin when you eat your morning and evening meals and a continuous low level of insulin in your body when you're not eating.

Because the insulins are injected in fixed proportions usually twice daily, it's less flexible than taking separate fast-acting and longer-acting insulin, or using a fast-acting insulin with a pump. You may need to keep to a similar diet and routine each day, as your insulin dose will be harder to adjust.

Biphasic insulin starts to work within 30 minutes after you take it, and its effects last at least 12 hours and sometimes up to 24 hours.

You can see images showing how long each type of insulin lasts on the NHS My Type 1 Diabetes website.

The insulins used to treat diabetes are very similar to the insulin produced naturally in the body. Insulins have been used to treat diabetes for over 100 years.

You should not have any long-term side effects as long as you use the right injection technique.

There are 3 main types of biphasic insulin:

• biphasic insulin aspart (NovoMix 30)
• biphasic insulin lispro (Humalog Mix 25 and Humalog Mix 50)
• biphasic isophane insulin (Humulin M3)

The Humulin M3 brand is a mixture of short-acting and intermediate-acting human insulins. Human insulin is the name given to insulin grown in the laboratory that is a copy of the insulin made by the human pancreas.

There are also insulin analogues which are versions of human insulin that have been modified to improve how they work, such as starting to work more quickly, lasting for longer or working more consistently.

Biphasic insulin aspart and biphasic insulin lispro contain human insulin analogues. These are very similar to the Humulin M3 brand but they start to work slightly quicker, so you may be able to take them with a shorter gap before eating.

Before human insulin was available, animal insulin was used, taken from the pancreases of pigs (porcine) or cows (bovine). There are still some people who need animal insulin because they cannot take human insulin.

There is 1 brand of porcine biphasic insulin called Hypurin Porcine 30/70. It has a very similar effect on blood glucose to the other biphasic insulins, but it's usually only used by people who had problems with hypos when they tried to change to human insulin.

Biphasic insulins (also known as mixed insulins) are very useful for people who have a regular routine for how they eat, sleep, drink alcohol and exercise.

A biphasic insulin gives you both the rapid-acting or short-acting insulin you need to cope with meals (bolus insulin) and the longer-acting insulin you need to keep your blood glucose low throughout the day and night (basal insulin). You'll be able to have fewer injections than if you take separate rapid or short and longer-acting insulins.

However, as the medicine contains fixed proportions of each type of insulin, it's less easy to adjust your dose to take account of any changes in your routine that may affect your blood glucose, such as changes in what you eat or how much exercise you do.

Speak to your doctor or diabetes nurse if you think the type of insulin you're taking is not working well to keep your blood glucose levels stable.

Metformin is usually the first choice of medicine for type 2 diabetes.

Other medicines used to treat type 2 diabetes include:

• alogliptin
• dapagliflozin
• empagliflozin
• gliclazide
• glimepiride
• pioglitazone
• saxagliptin
• sitagliptin

These medicines are all taken as tablets.

There are also other medicines taken as injections, such as semaglutide, dulaglutide, liraglutide and exenatide.

Some people with type 2 diabetes find that their diabetes medicines stop working as well after a couple of years. This can be because the pancreas begins to make less insulin or the body becomes more resistant to the insulin it makes.

Many people with type 2 diabetes need to take a combination of different medicines to manage their blood glucose levels. Eventually some people need to take insulin because their pancreas is not making enough insulin itself.

Often insulin is used as well as the other medicines, but sometimes people will be able to reduce the number of other medicines by carefully adjusting their dose of insulin to manage their blood glucose without causing hypos.

If you have diabetes, you're entitled to free prescriptions for all of your medicines, not just your diabetes ones.

To claim your free prescriptions, you'll need to have a medical exemption certificate.

The application form for the medical exemption certificate is called FP92A. You can get this from your GP surgery.

You'll need to fill in the form, then your doctor will sign it and send it off.

When you first start taking insulin you may notice that you start to put on weight. This is because of the way insulin works to use glucose from food to produce energy and store any extra as fat.

You might have also lost weight before your diagnosis, and so you might put some weight back on once your blood glucose is back within target.

If you're concerned about putting on weight, talk to your healthcare team who can advise on diet, lifestyle and adjusting your insulin dose as you change your diet.

Having a healthy weight and eating a balanced diet can help with symptoms of type 2 diabetes and gestational diabetes.

Make sure that the surgical team knows you're taking insulin before you have any surgical procedure. They'll tell you whether you need to adjust your dose before the procedure and what to expect afterwards for your doses and testing your blood glucose levels.

Always take your insulin to hospital with you, and tell the staff what types of insulin you take and your usual doses.

Biphasic insulin is not suitable to use in an insulin pump. If you switch to an insulin pump you'll take a rapid-acting insulin only.

Insulin pumps may be available on the NHS to people aged 12 years old and over with type 1 diabetes who either:

• have frequent problems with hypos, and whose hypos are hard to predict
• have high blood sugar levels despite carefully managing their diabetes and taking insulin several times a day – this is defined as an HbA1c level of 8.5% (or 69mmol/mol) or higher

For children under 12 years old, insulin pumps may be available if having several injections a day is not practical. However, children with insulin pumps are expected to have a trial of using insulin pens when they're between 12 and 18 years old, to see whether they can switch.

If you have type 2 diabetes or gestational diabetes, you will not usually be eligible for an insulin pump from the NHS.

If you're interested in switching to an insulin pump and think you meet the criteria, discuss this with your diabetes specialist.

Everyone who takes insulin needs to monitor their blood glucose. The kit you need to do this is available from the NHS.

For most people the target blood glucose range is between 4 and 7mmol/L, although some people are given a wider range, and slightly higher levels after eating are OK. Hypo symptoms are more likely when blood glucose falls below 4mmol/L.

How often you'll need to check your blood glucose depends on the type of diabetes you have, how carefully you need to manage your blood glucose, how often you have hypos, and how often you drive or use machinery.

You may need to check your blood glucose more often when you're ill, during pregnancy, if you're fasting, or if you're doing shift work.

You may be given a blood glucose monitor that you wear on your body, to check your blood glucose levels at any time.

You'll also be given equipment to check your blood glucose levels with a finger-prick test. This involves using a lancet and finger-prick device to get a drop of blood from your fingertip. You then use a test-strip and meter to measure the amount of glucose that is in the blood sample.

You'll be trained to do a finger-prick test when you start taking insulin. You'll also be told how to adjust your insulin dose according to the results.

Diabetes UK has more information about checking blood glucose levels.

Some people use a continuous glucose monitor (CGM) or flash monitor to check their blood glucose levels at any time.

This is a small sensor that you attach to your arm or tummy that measures how much glucose is in the fluid (interstitial fluid) under the skin. It may come with a reader or receiver that shows the results, or you can download an app to see the results on a smartphone.

With CGM, the results are sent to the receiver wirelessly every few minutes, so you can see the results at any time. Some devices can send results to an insulin pump. Most types of CGM have an alarm that can alert you when your blood glucose is too low or too high.

With a flash monitor you need to scan the sensor with your reader or smartphone to see the results.

Interstitial fluid glucose readings are a few minutes behind your blood glucose levels. This means that you'll still need to do finger-prick checks every now and then, particularly when you have a hypo.

If you have type 1 diabetes, you should be able to get a monitor on the NHS.

If you have type 2 diabetes, you should be able to get a monitor on the NHS if you take insulin at least twice a day and you meet any of these criteria:

• you have frequent or severe hypos
• you have a disability that makes it difficult to do a finger-prick test
• you need to test your blood glucose at least 8 times a day

If you have gestational diabetes, you should be able to get a monitor on the NHS if you take insulin and you have severe hypos or your blood glucose is not stable.

Speak to your doctor or diabetes specialist if you're interested in using a CGM or flash monitor and you think you meet these criteria.

Learn more about CGM and flash from Diabetes UK.

Yes, you can take insulin abroad, but you need to plan ahead. Get a letter from your GP or diabetes care team to say you have diabetes and need to take insulin and other diabetes equipment with you, such as pens and needles. You may need to pay for the letter.

You'll also need to check with the airline if you use an insulin pump or continuous glucose monitor (CGM) or flash monitor.

Use a suitable cool bag to transport your insulin safely and keep it at the right temperature. If you're flying, take your insulin in your hand luggage.

If you're crossing several time zones, get advice from your doctor or diabetes nurse on how to adjust your insulin doses.

Check how you can get insulin in the country you're visiting, and take a recent prescription with you.

Find out more about travelling with insulin from Diabetes UK.

Biphasic insulin will not stop any type of contraception from working, including the combined pill and emergency contraception.

But you might need a small adjustment in your insulin dose after starting contraceptive pills.

That's because contraceptive pills change how your body handles sugar.

If you drive a car you must notify the Driver and Vehicle Licensing Agency (DVLA) when you start taking insulin.

Always check your blood glucose before driving, a maximum of 2 hours before starting your journey. You'll also need to check your blood glucose every 2 hours if you're driving on a long journey.

Your blood glucose must be 5mmol/L or higher to drive. If it's between 4 and 5mmol/L, have a starchy snack before starting to drive. If it's less than 4mmol/L, treat the hypo and do not drive for at least 45 minutes after you've recovered.

Always carry glucose and your glucose meter in the car with you.

Find out more about diabetes and driving from GOV.UK.

If you ride a bike, it's important to be aware of the risk of hypos and carry glucose with you in case you feel one coming on. If you're going on a strenuous bike ride, test your blood glucose before setting off and follow the advice you've been given about adjusting your insulin dose when you're exercising.

Yes, you can drink alcohol while taking biphasic insulin, but it's best to drink no more than 2 units per day. A standard glass of wine (175ml) is 2.3 units. A pint of lager or beer is usually 2 to 3 units of alcohol.

Drinking more than this can increase the risk of a hypo, especially if you drink alcohol on an empty stomach. Hypos can happen up to 24 hours after drinking alcohol.

Many alcoholic drinks also contain a lot of sugar and it can be difficult to work out if you need to adjust your insulin dose with these drinks.

If you do want to drink alcohol regularly, discuss this with your doctor or diabetes nurse. Try to keep to the recommended guidelines of no more than 14 units of alcohol a week, spread over 3 days or more.

There are no foods you need to avoid because you're taking insulin.

However, unless you're treating a hypo it's usually best not to drink sugary drinks or fruit juices if you're feeling thirsty, as this can increase your blood glucose levels very quickly.

You should be offered appointments with a dietitian to work out a healthy balanced diet that suits your tastes and lifestyle.

It's important to eat regular meals as skipping meals can affect your blood glucose levels and the dose of insulin you need.

Be careful eating food and drink containing karela (also called bitter gourd). This is because it can lower your blood glucose levels and you may need to adjust your insulin for this. Karela is used to flavour foods such as curries like bitter gourd masala. It has a bitter taste and is also made into juice and tea.

Having a healthy, balanced diet and exercising regularly will help you keep to a healthy weight and help improve your blood glucose levels. This will help you avoid symptoms and complications of type 2 diabetes.

Your doctor or diabetes nurse can advise you on what kinds of exercise are best for you and how you can safely build up your level of exercise.

If you're doing more strenuous exercise, get advice about taking snacks or reducing your insulin dose before you exercise and checking your blood glucose levels before and after exercise.

Read more about food and keeping active if you have type 2 diabetes.