Type 2 Diabetes Medications Explained: Metformin, Ozempic and More

This is general information about the medicines used for type 2 diabetes. It does not replace your doctor’s advice, and it should not be used to start, stop or change any medicine on your own.

Lifestyle change is the foundation of type 2 diabetes treatment, but many people also need medication — either from diagnosis or over time. Needing medication is not a failure. Some medicines are chosen specifically because they protect the heart and kidneys as well as lowering glucose.

This guide explains the main options and their common side effects, with the Australian brand names. For the overall picture see our type 2 diabetes management guide, and for eating and weight loss see the diet and lifestyle guide.

How your doctor chooses a medicine

The right medicine depends on more than your glucose result. Your GP will also consider your:

• weight
• kidney function
• heart and cardiovascular risk
• other medical conditions
• pregnancy plans
• medication side effects
• personal preferences
• medication costs and PBS eligibility

Two people with the same HbA1c can reasonably be prescribed quite different medicines.

Metformin

Metformin is commonly the first medication prescribed for type 2 diabetes. In Australia it is sold under brand names including Diabex, Diaformin and, as an extended-release tablet, Metex XR (as well as generic metformin).

It mainly works by reducing the amount of glucose released by the liver and improving the way the body responds to insulin. Advantages of metformin include:

• extensive experience with its use
• a low risk of causing hypoglycaemia when used alone
• it generally does not cause weight gain
• it is available as an inexpensive tablet

Metformin is usually taken with food and increased gradually. A slow-release or extended-release version (such as Metex XR) may be easier to tolerate for some people.

Common metformin side effects

The most common side effects involve the digestive system:

• diarrhoea
• nausea
• abdominal discomfort
• cramping
• bloating
• reduced appetite
• an altered or metallic taste

These symptoms often improve during the first few weeks. Starting at a low dose, increasing gradually and taking metformin with food can improve tolerance.

Long-term metformin use can sometimes contribute to vitamin B12 deficiency. Your doctor may occasionally check your B12 level, particularly if you develop anaemia, numbness or tingling.

Metformin-associated lactic acidosis is extremely rare but serious. The risk is greater during severe dehydration, major acute illness or significant kidney impairment. Your doctor may advise you to temporarily stop metformin during certain illnesses, operations or medical investigations. Metformin does not usually damage healthy kidneys, but your kidney function must be checked to ensure your body can clear the medicine safely.

Ozempic and other GLP-1 medicines

Ozempic is the brand name for semaglutide, a medicine from the GLP-1 receptor agonist family. It is a once-weekly injection used in adults with type 2 diabetes. It is not insulin.

Ozempic can:

• increase insulin release when blood glucose is elevated
• reduce the release of glucagon, a hormone that raises glucose
• slow the early movement of food through the stomach
• reduce appetite
• improve glucose levels
• assist some people with weight loss

Ozempic may be considered when lifestyle measures and other medication are not providing adequate control, when metformin is unsuitable, or when its broader metabolic, cardiovascular or kidney benefits make it an appropriate choice. It is not automatically the best first medicine for every newly diagnosed patient.

Other GLP-1 (and GIP/GLP-1) medicines available in Australia

• Rybelsus — oral semaglutide, a daily tablet form of the same medicine as Ozempic, taken on an empty stomach with a small sip of water.
• Trulicity — dulaglutide, another once-weekly GLP-1 injection.
• Mounjaro — tirzepatide, a once-weekly injection that acts on both the GIP and GLP-1 systems; it can be a very effective glucose- and weight-lowering treatment.

A note on names: Wegovy (semaglutide) and Saxenda (liraglutide) are the registrations of related medicines specifically for weight management rather than diabetes. The diabetes and weight-loss products are prescribed under different rules and are not interchangeable. Some of these medicines — Ozempic in particular — have been affected by supply shortages in Australia, which can influence what your doctor is able to prescribe at any given time.

Common Ozempic and GLP-1 side effects

The most common side effects are gastrointestinal and are often most noticeable after starting treatment or increasing the dose:

• nausea
• diarrhoea
• vomiting
• constipation
• reflux or indigestion
• abdominal discomfort
• bloating or burping
• reduced appetite

Starting at a low dose and increasing gradually helps reduce these effects. Eating smaller meals, stopping when comfortably full and avoiding very rich or fatty meals may also help.

Vomiting and diarrhoea can cause dehydration and occasionally worsen kidney function. Contact your doctor if you cannot keep fluids down, are passing much less urine than usual or feel significantly unwell.

Seek urgent medical assessment for:

• severe or persistent abdominal pain, particularly if it travels through to the back
• repeated vomiting or inability to drink
• severe abdominal swelling, constipation and vomiting
• facial swelling, wheezing or difficulty breathing
• sudden or significant changes in vision

A few further points:

• These medicines should not be used during pregnancy.
• Tell your treating doctor before surgery or a procedure requiring general anaesthesia or deep sedation, because these medicines can delay stomach emptying.
• People with existing diabetic retinopathy may require closer eye monitoring, particularly if their glucose improves rapidly.

SGLT2 inhibitor medicines

Medicines such as empagliflozin (Jardiance) and dapagliflozin (Forxiga) help the kidneys remove excess glucose through the urine. They are also available combined with metformin in a single tablet — for example Jardiamet (empagliflozin with metformin) and Xigduo XR (dapagliflozin with metformin).

They may be particularly useful for some patients with:

• chronic kidney disease
• heart failure
• cardiovascular disease
• a need for additional glucose lowering without significant hypoglycaemia

Possible side effects include:

• genital thrush
• increased urination
• dehydration
• dizziness
• urinary symptoms

A rare but serious complication is diabetic ketoacidosis, which can sometimes occur even without an extremely high glucose level. People taking these medicines need clear sick-day and fasting instructions, particularly before operations or procedures — this usually means temporarily stopping the medicine when acutely unwell, unable to eat and drink normally, or before surgery.

Sulfonylureas

Sulfonylureas stimulate the pancreas to release more insulin. Common Australian examples include gliclazide (Diamicron MR) and glimepiride (Amaryl).

They lower glucose effectively and are inexpensive, but because they increase insulin they can cause hypoglycaemia (low blood glucose) and may cause some weight gain. People taking a sulfonylurea usually need to understand the symptoms of hypoglycaemia and how to treat it, and glucose monitoring is often recommended.

DPP-4 inhibitors

DPP-4 inhibitors work in the same broad pathway as GLP-1 medicines but as a daily tablet, and with a more modest effect. Australian examples include sitagliptin (Januvia), linagliptin (Trajenta) and vildagliptin (Galvus), and combinations with metformin such as Janumet, Trajentamet and Galvumet.

They are generally well tolerated, are weight-neutral and rarely cause hypoglycaemia on their own, which can make them a reasonable option for some people — although they do not offer the heart and kidney benefits of the GLP-1 and SGLT2 groups.

Insulin

Insulin remains an important and effective treatment. It may be added when other treatments are not achieving your target, when glucose is very high at diagnosis, during illness or surgery, or in other particular circumstances.

Insulin can cause hypoglycaemia and generally requires glucose monitoring and education on dosing and sick-day management. Needing insulin is not a personal failure — it is one of several tools, and in some people it can later be reduced or stopped as other measures take effect.

Will I need to check my glucose every day?

Not necessarily. Regular finger-prick testing is particularly important for people taking insulin or medicines that can cause hypoglycaemia (such as sulfonylureas). For someone taking only metformin, a GLP-1 medicine such as Ozempic, or certain other medicines with a low risk of hypoglycaemia, daily testing may not provide much benefit. The need for glucose testing should be individualised according to your medications, HbA1c, symptoms, illnesses and treatment plan.

Getting your medication reviewed

Diabetes medicines change over time as your needs change, so a regular review matters. Our GPs at Ivanhoe and Diamond Creek can review whether your current medicines still suit you, discuss options such as metformin, Ozempic, Jardiance and others, and develop a sick-day medication plan. Book a diabetes appointment to talk it through.

This page provides general patient education and does not replace individual medical advice. Medication choice must be tailored to your test results, kidney function, other medical conditions and personal circumstances. Do not start, stop or change a prescribed medicine without discussing it with your doctor.

References

• Management of type 2 diabetes: A handbook for general practice — RACGP and Diabetes Australia.
• Australian Diabetes Society (ADS) — peak medical and scientific body for diabetes in Australia.
• Type 2 diabetes — medication and treatment — Diabetes Australia.
• National Diabetes Services Scheme (NDSS) — Diabetes Australia / Australian Government.