There are many types of medicines that can be prescribed to help manage type 2 diabetes. Each medicine works in a different way to control blood glucose levels and each will have their own benefits and side effects.

Metformin, sulfonylureas and insulin are medicines commonly prescribed for diabetes and have been used for many years.

Over the past decades, a number of other glucose-lowering medicines have also become available. These include medicines known as acarbose, gliptins, glitazones, GLP-1 analogues and SGLT2 inhibitors. Read on to learn more about these medicines, or use our Medicine Finder to find out more about the medicines you have been prescribed.

Taking your medicine exactly as prescribed should improve your blood glucose control and give you more energy, better sleep and fewer days off work. It can also help prevent, delay or minimise your risk of developing complications of type 2 diabetes.

If you are taking several medicines, you may find a Home Medicines Review by a pharmacist useful in managing your medicines.

A medicines list can help you keep track of all the medicines you are taking, including prescription, over-the-counter, herbal and natural medicines. To get the best out of a medicines list make sure that you:

• keep it up to date by removing any medicines you are no longer using and adding new medicines as you start using them,
  
• take it with you each time you visit your doctor, pharmacist or health professional, or if you go into hospital,
  
• keep it with you at all times in case of emergency.
  

If you experience unpleasant side effects, do not stop taking your medicine. Talk to your health professional, as they may be able to alter the dose, timing, formulation or medicine, to minimise adverse effects.

Phone for medicines information

Call Medicines Line on 1300 MEDICINE (1300 633 424) to get information about your prescription, over-the-counter and complementary medicines (herbal, 'natural', vitamins and mineral supplements) from a pharmacist. Your call will be answered by healthdirect Australia.

Metformin lowers blood glucose by reducing the amount of glucose that the liver releases into the bloodstream, and by increasing the amount of glucose taken up by cells of the body.

It is the medicine that most people with type 2 diabetes start taking when diet and exercise are no longer enough to keep blood glucose levels on target. Metformin is very unlikely to cause abnormally low blood glucose levels or ‘hypos’ (hypoglycaemia) and does not cause weight gain and may help weight loss, so it is particularly suitable for people who are overweight

Metformin may also help reduce the risk of cardiovascular disease in people with type 2 diabetes by lowering ‘bad cholesterol’ (low-density lipoprotein [LDL]) and triglycerides (another kind of fat in the blood).

There are many brands available that contain metformin, alone or in combination with other diabetes medicines.

What are the side effects of metformin?

Common side effects of metformin include:

• diarrhoea
  
• feeling sick (nausea)
  
• being sick (vomiting)
  
• stomach upset, cramps and bloating (gastrointestinal side effects).
  

Up to three in 10 people taking metformin will experience these gastrointestinal side effects. The side effects can depend how much you are taking (the larger the dose, the worse the side effects).

Increasing the dose slowly over time to the required dosage and taking metformin with food helps to minimise gastrointestinal side effects.

Sulfonylureas is the general name for a group of medicines that lower blood glucose levels by increasing the amount of insulin made by the pancreas. 

A sulfonylurea may be prescribed for people with type 2 diabetes who cannot take metformin. More commonly, it is used in addition to metformin, if diet, exercise and metformin are not able to control blood glucose levels adequately.

There are a number of different medicine active ingredients that belong to the sulfonylurea group including:

• glibenclamide
  
• gliclazide
  
• glimepiride
  
• glipizide

What are the side effects of sulfonylureas?

Common side effects of sulfonylureas include:

• weight gain
  
• abnormally low blood glucose levels (hypoglycaemia).
  

Hypoglycaemia is up to five times more likely with sulfonylureas than with any other oral diabetes medicine, particularly in older people, and in people with liver or kidney problems.

Less frequent side effects include nausea, diarrhoea, headaches and allergic reactions.

Insulin is a hormone produced by the pancreas that helps to control glucose levels in the blood stream. People with diabetes may not produce enough insulin, so a manufactured insulin can be injected instead. The manufactured insulin does exactly the same job as your body’s own insulin would.

Insulin is available in several different types and forms (vials, cartridges or pre-filled pens), which differ in how quickly they work (very short-acting, short-acting, intermediate-acting and long-acting) and how long they last in the body (4–24 hours). These insulin types also vary in the number of injections needed per day, the size of each dose and the timing of the injection. The overall aim of treatment is to keep insulin levels as steady as possible over a 24-hour period to cover rises in blood glucose levels following meals and to keep glucose levels within the desired range.

For people who need frequent insulin injections, an insulin pump can be a convenient alternative.

What are the side effects of insulin?

• Weight gain is likely with insulin.
  
• Hypoglycaemia (low blood glucose) is more likely with insulin than with other medicines for diabetes. Most often, hypoglycaemia is caused by using a larger dose of insulin than normal, having late or missed meals, not eating enough food, or increased physical activity.
  
• Allergic reactions are also possible, but rare. Some people get skin reactions at the injection sites.
  

Acarbose works by preventing the carbohydrate you eat from being broken down into glucose. This delays glucose absorption in the intestine and prevents glucose from entering the blood stream too quickly. Acarbose can be used alone or added to other diabetes medicines (eg, metformin, sulfonylureas and insulin).

What are the side effects of acarbose?

Common side effects with acarbose include:

• flatulence (wind), stomach pain and bloating, and diarrhoea
  
• inability to digest carbohydrates other than glucose when blood sugar is low (hypoglycaemia).
  

Rarely, acarbose can also cause liver problems, skin reactions and swelling due to fluid build-up (oedema), blockage of the small and/or large intestine (ileus), and anaemia (a reduced number of red blood cells).

Gliptins is a name given to a group of medicines called dipeptidyl peptidase-4 (DPP-4) inhibitors. Gliptins increase the amount of insulin in the blood through their action on hormones called incretins. They also reduce the amount of glucose produced by the liver. Gliptins are not prescribed on their own but are often used in combination with other oral diabetes medicines (metformin, a sulfonylurea or a glitazone). There does not appear to be any difference between the gliptins in terms of controlling blood glucose levels – they are all as effective as each other.

There are a number of different active ingredients that belong to the gliptin group including:

• sitagliptin
• vildagliptin
• saxagliptin
• linagliptin
• alogliptin

What are the side effects of gliptins?

Compared with metformin, sulfonylureas and insulin, gliptins are relatively new medicines, so their long-term side effects and benefits are still not fully understood. Gliptins can cause:

• headaches and cold-like symptoms
• hypoglycaemia used with a sulfonylurea or insulin
• pancreatitis (inflammation of the pancreas that can result in severe, long-lasting abdominal pain) is rare but has been reported in clinical trials.

Allergic reactions to the gliptin occur very rarely. Seek medical attention if there is any swelling of the face, mouth, tongue or throat.

Talk to your health professional if you have any concerns.

Glitazones is the name of a group of medicines called thiazolidinediones. Glitazones lower blood glucose levels by helping the body to use insulin better by reducing insulin resistance in the tissues of the body. The glitazones are:

• pioglitazone
  
• rosiglitazone (not available as a single medicine, only in combination with metformin)
  

These medicines are typically prescribed in combination with other oral diabetes medicines. Pioglitazone can be added to metformin or a sulphonylurea. Rosiglitazone can be added to metformin and is available as a combination tablet (Avandamet).

What are the side effects of glitazones?

Glitazones are known to commonly cause:

• muscle pain
  
• water retention and weight gain
  
• headaches and dizziness
  
• joint pain (arthralgia)
  
• hypoglycaemia (low blood sugar)
  
• lower iron (haemoglobin) levels in the blood.
  

Less frequently, bone fractures in women have been linked to glitazones and in rare cases, glitazones can cause heart failure, liver damage and fluid accumulation in the lungs (pulmonary oedema).

Rosiglitazone may increase the risk of a heart attack (myocardial infarction), fluid retention in the eye (diabetic macular oedema) that can affect vision, and increased levels of ‘bad’ LDL cholesterol. Pioglitazone may slightly increase the risk of developing bladder cancer when used for more than 1 year.

Talk to your health professional if you have any concerns.

Glucagon-like peptide-1 (GLP-1) analogues are a relatively new group of medicines that can be prescribed for treating type 2 diabetes. GLP-1 analogues reduce the level of glucose in the blood by increasing the amount of insulin in the blood, reducing the amount of glucose produced by the liver, and helping the stomach to empty more slowly so that glucose is absorbed more slowly. These medicines are given as injections under the skin (a subcutaneous injection) and are available as pre-filled disposable injector pens. A health professional can demonstrate how to use these pens. GLP-1 analogues are injected before a meal, and should not be used after a meal.

GLP-1 analogue medicines include:

• exenatide (Byetta) – twice daily dosing
• exenatide (Bydureon) – once weekly dosing
• liraglutide (Victoza) – once daily dosing. Liraglutide is not subsidised under the Pharmaceutical Benefits Scheme (PBS)
• lixisenatide – once daily dosing. Lixisenatide is not subsidised under the PBS.

What are the side effects of GLP-1 analogues?

Compared with metformin, sulfonylureas and insulin, GLP-1 analogues are new diabetes medicines, so their long-term side effects and benefits are still not fully understood. Common side effects of GLP-1 analogues include:

• nausea and/or vomiting – the nausea will probably subside within a week or two; otherwise, your doctor may decide you need to stop taking the medicine
  
• diarrhoea or constipation
  
• acid reflux
  
• hypoglycaemia (low blood glucose) when used together with a sulfonylurea or insulin.
  

GLP-1 analogues are usually started at a small dose, and gradually increased to help reduce possible stomach and bowel side effects.

Less frequent side effects include allergic reactions, pancreatitis (swelling of the pancreas) and kidney problems.

Sodium–glucose co-transporter 2 inhibitors, also known as SGLT2 inhibitors or ‘flozins’, are a new group of diabetes medicines. SGLT2 inhibitors reduce blood glucose levels by removing excess glucose from the blood into the urine. They are not prescribed on their own, but can be used in combination with other diabetes medicines.

SGLT2 inhibitors include

• dapagliflozin
  
• empagliflozin
  
• canagliflozin (deleted from the Pharmaceutical Benefits Scheme from 1 August 2015).

SGLT2 inhibitors are a new group of medicines, so their long-term benefits, including those that may affect the heart and circulation, are not fully known. Clinical trials have reported that one of these medicines, empagliflozin, can decrease heart complications and deaths associated with diabetes. SGLT2 inhibitors may also cause modest weight loss and also reduce systolic blood pressure in some people.

What are the side effects of SGLT2 inhibitors?

Common side effects include genital infections, and hypoglycaemia (when used together with sulfonylurea or insulin).1 Less frequent side effects include dehydration, low blood pressure (hypotension)and ketoacidosis. 

If you are taking an SGLT2 inhibitor and experience any of the following signs and symptoms, seek medical help immediately:

• feeling sick or being sick
  
• stomach pain
  
• fast and deep breathing
  
• different smelling urine or sweat
  
• a sweet smell to the breath.
  

People with type 2 diabetes often have other health problems as well, like high blood pressure and high cholesterol, which means they are at greater risk of the complications of diabetes, such as blood clots, heart attack or stroke. So, even if you are taking medicines to control your diabetes, you may also need to take medicines for these conditions, as well as adopting lifestyle changes. The medicines you might need to take for type 2 diabetes-related problems include:

• medicines to lower fats (triglycerides) and cholesterol in the blood
• medicines to treat high blood pressure
• aspirin to prevent further heart and circulatory (cardiovascular) problems.

Controlling high blood pressure is as important as controlling blood glucose

One of the common complications of diabetes is vascular disease, which affects the large and small blood vessels (arteries) that carry blood around the body. Vascular disease can affect your sight, your kidney function and your nerves. If you have diabetes and high blood pressure, your risk of getting vascular disease is much higher than people without diabetes (up to six times higher).

It is therefore very important to make sure your blood pressure is well controlled to lower your risk of getting vascular disease. You can do this by:

• following a healthy diet
  
• quitting smoking
  
• taking physical exercise
  
• cutting down on salt
  
• limiting alcohol.
  

Your doctor may also recommend that you take medicines to lower your blood pressure or cholesterol.

Managing multiple conditions can mean that you are taking several medicines. So understanding how to manage your diabetes medicines well and what help is available can help you feel more in control of your health.

Medicines that you take — including prescription, over-the-counter and complementary medicines (herbal, ‘natural’, vitamins and minerals) — can change your blood glucose levels and may interact with your diabetes medicines. It is important to tell your health professional about all the medicines you are taking, as your doctor may need to adjust your dose of diabetes medicine, or make changes to your other medicines.

Medicines that can raise blood glucose levels

• adrenaline
• asthma medicines (not common with inhaled asthma medicines but may occur with high doses or if injected)
• antipsychotic and antidepressant medicines (some)
• baclofen
• ciclosporin, sirolimus and tacrolimus
• nicotinic acid
• isotretinoin
• phenytoin (increased blood glucose is a rare side effect of this medicine)
• corticosteroids with glucocorticoid effects (not fludrocortisones)
• thiazide diuretics

Medicines that can lower blood glucose levels

Below are some medicines that are known to decrease blood glucose levels to some extent as a side effect. They are not prescribed for this purpose.

• aspirin (taken at doses required for pain relief)
• beta blockers
• non-selective monoamine oxidase inhibitors
• quinine (as an antimalaria medicine)
• trimethoprim with sulfamethoxazole