Diabetes Medicines: Insulin, GLP-1 & SGLT2 Explained

There are several groups of medicines used to treat Type 2 diabetes. They do not all work in the same way.

Some mainly reduce blood glucose. Others also affect appetite, body weight, the heart or the kidneys. Some increase the amount of insulin released by the pancreas, while others help the body use insulin more effectively.

Here is a simple overview.

These groups are not interchangeable. A medicine that is appropriate for someone with kidney disease may not be the preferred option for someone with a different health problem.

Sometimes two or more medicines are used together.

The starting point is your overall health, not just one blood sugar reading.

Your doctor may look at your HbA1c, fasting glucose, after-meal glucose, weight, kidney function, blood pressure and cardiovascular risk. Your current medicines and any previous side effects are also relevant.

How high is your blood sugar?

HbA1c gives an estimate of average blood glucose over the previous 2 to 3 months.

A person whose HbA1c is only slightly above the desired range may have very different treatment needs from someone with very high glucose and symptoms.

The urgency of treatment can therefore differ from one person to another.

Do you have heart disease?

Diabetes and cardiovascular disease often occur together.

If someone has established cardiovascular disease or certain cardiovascular risks, the doctor may favour medicines that have demonstrated cardiovascular benefits in appropriate patients.

In such cases, the discussion is not only about lowering HbA1c. Protecting the heart may also be part of the treatment decision.

How are your kidneys?

Kidney function affects the choice and use of several diabetes medicines.

Some SGLT2 inhibitors have kidney-protective effects in appropriate patients with chronic kidney disease. This is one reason doctors may consider them even when another medicine might also lower blood glucose.

Kidney function should therefore be considered before selecting or changing some diabetes medicines.

Is weight a concern?

Weight and Type 2 diabetes are closely connected.

Excess body weight can increase insulin resistance. Some diabetes medicines can be associated with weight gain, while others may help with weight reduction.

GLP-1 receptor agonists and dual GIP/GLP-1 medicines may be considered for selected people who need both better glucose control and help with weight management.

You can also read about obesity and weight management at Medcare.

Could the medicine cause low blood sugar?

Low blood sugar, or hypoglycaemia, occurs when glucose falls too low.

You may feel shaky, sweaty, hungry, weak, dizzy or confused. Severe hypoglycaemia can cause loss of consciousness or seizures.

Insulin and some medicines that stimulate insulin release can increase this risk. The risk needs particular attention in older adults, people with kidney problems and people whose meals or activity levels vary considerably.

What other conditions do you have?

A person with Type 2 diabetes may also have high blood pressure, obesity, fatty liver, sleep apnea, heart disease or other medical problems.

These conditions can change the choice of medicine.

That is why two people with the same HbA1c may receive completely different prescriptions.

Metformin is one of the most familiar medicines used for Type 2 diabetes.

It reduces the amount of glucose released by the liver and helps the body respond better to insulin.

It is often used early in treatment when there is no reason to avoid it. Depending on the person's health, it may be used alone or combined with another medicine.

The idea that every person with Type 2 diabetes must start with the same medicine is too simple. Treatment has become more individualised.

What are the common side effects of metformin?

The main side effects involve the digestive system.

Some people experience:

• Nausea
• Loose stools or diarrhoea
• Abdominal discomfort
• Reduced appetite
• A metallic taste

These symptoms are often more noticeable when treatment begins.

Kidney function is important when deciding whether metformin is appropriate. Your doctor may also consider vitamin B12 testing during long-term treatment when there is a clinical reason to do so.

If digestive symptoms are persistent or troublesome, tell your doctor rather than stopping the medicine yourself.

No.

Metformin is a useful medicine for many people, but it is not automatically the best option in every situation.

A doctor may choose another medicine because of cardiovascular disease, heart failure, kidney disease, obesity, side effects, contraindications or other treatment priorities.

Sometimes more than one medicine is needed from the outset.

The aim is to find a treatment plan that is effective and safe for that particular person.

GLP-1 stands for glucagon-like peptide-1.

GLP-1 receptor agonists act on a hormone pathway involved in blood glucose regulation, appetite and digestion.

Depending on the medicine and its approved use, GLP-1 medicines can:

• Improve blood glucose control
• Slow stomach emptying
• Increase the feeling of fullness
• Reduce appetite
• Support weight loss in appropriate patients

They are prescription medicines. They are not suitable for everyone with diabetes or everyone who wants to lose weight.

The doctor needs to consider the person's medical history, current medicines, weight, glucose control and possible side effects.

Medcare also provides information about GLP-1 medicines for weight management.

These medicines act on two hormone pathways, GIP and GLP-1.

They can improve blood glucose control and may also have a substantial effect on appetite and body weight in suitable patients.

Their use still needs medical assessment.

A medicine being effective for weight loss does not automatically make it appropriate for every person with diabetes. The potential benefits have to be weighed against side effects, medical history and other treatment options.

Digestive symptoms are among the most common.

These may include:

• Nausea
• Vomiting
• Diarrhoea
• Constipation
• Abdominal discomfort
• Reduced appetite

Some people have few problems, while others find the digestive effects difficult.

Persistent vomiting, severe abdominal symptoms or other concerning symptoms should be discussed with a doctor.

There are also medical conditions in which these medicines may not be suitable.

Do not use an injectable diabetes or weight-loss medicine simply because it was prescribed to someone you know.

No.

Their role is broader than treating very high glucose.

In selected patients, they may be considered because the person also has obesity, needs help with weight management or has certain cardiovascular risk factors.

At the same time, having Type 2 diabetes does not automatically mean that a GLP-1 medicine is necessary.

The decision depends on the whole clinical picture.

SGLT2 inhibitors are medicines that work partly through the kidneys.

They reduce the amount of glucose that is reabsorbed into the bloodstream, allowing some glucose to leave the body in urine.

SGLT2 stands for sodium-glucose cotransporter 2.

Their role is not limited to blood sugar control. Certain medicines in this group can also provide important benefits for selected people with heart failure, cardiovascular disease or chronic kidney disease.

What side effects can SGLT2 inhibitors cause?

Because these medicines increase glucose loss through urine, some people may develop genital fungal infections.

There can also be an increased risk of dehydration, particularly in situations where fluid intake is poor.

Rarely, a serious condition called diabetic ketoacidosis can occur. In some cases, blood glucose may not be extremely high when this happens.

The risk can be affected by illness, fasting and other circumstances. Your doctor may give you specific instructions about what to do during periods of illness or before certain procedures.

Follow those instructions rather than making changes based on advice from social media or other patients.

Some SGLT2 inhibitors have benefits that go beyond lowering glucose.

In appropriate people with Type 2 diabetes and chronic kidney disease, they may help slow kidney disease progression and reduce certain cardiovascular risks.

This is one reason a doctor may consider an SGLT2 inhibitor even when the patient's glucose level is not the only concern.

Kidney function and the rest of the person's medical history still have to be considered.

Insulin is the hormone that allows glucose to move from the bloodstream into cells where it can be used for energy.

In Type 2 diabetes, the body may initially make enough insulin but become resistant to its effects. Over time, insulin production can also fall.

Insulin may be considered when:

• Blood glucose is very high
• HbA1c is markedly elevated
• There are significant symptoms of high blood sugar
• There is unexplained weight loss
• Ketones are present
• Diabetic ketoacidosis occurs
• A person is seriously unwell
• Other medicines are no longer providing adequate control
• Insulin is needed during pregnancy or another specific medical situation

The decision depends on the reason for the high glucose and the person's overall condition.

Not necessarily.

This is one of the most common concerns patients have after being told that insulin is needed.

Sometimes insulin is used for a limited period. A person who becomes severely unwell, for example, may temporarily need insulin while the illness is treated.

For other people, insulin becomes a long-term treatment because the pancreas has gradually lost some of its ability to produce insulin.

Starting insulin is not a sign that someone has failed.

It is simply another way of providing the insulin the body needs.

No.

Insulin itself does not damage the kidneys simply because it is being used.

Poorly controlled diabetes can damage the kidneys over many years. In a person who needs insulin, controlling high blood glucose can be an important part of reducing the effects of prolonged hyperglycaemia.

Insulin does need careful use because too much can cause hypoglycaemia.

If you have concerns about insulin, discuss them with your doctor rather than delaying treatment because of fear.

Yes.

It is common for Type 2 diabetes treatment to involve more than one medicine, particularly when one medicine no longer provides enough glucose control.

Different medicines affect different parts of the glucose regulation system. Combining them can sometimes provide better control without relying on a single medicine.

The combination depends on the person's health, kidney function, weight, cardiovascular risk and risk of hypoglycaemia.

Type 2 diabetes can change over time.

The pancreas may gradually produce less insulin. Body weight can change. Physical activity may decrease. Sleep problems, infections, stress and other illnesses can also affect glucose levels.

As a result, a treatment that worked well several years ago may no longer be enough.

This does not necessarily mean you have done something wrong.

Your treatment simply may need to be reassessed.

No, not without medical advice.

If your blood glucose is normal while taking medicine, the treatment may be one of the reasons it is normal.

Stopping it suddenly can cause glucose levels to rise again. With some medicines, stopping or changing treatment without guidance can create additional risks.

If your glucose has improved significantly, tell your doctor. The treatment can then be reviewed properly.

Most diabetes medicines do not cure Type 2 diabetes.

Some people can achieve remission, which means their blood glucose remains below the diabetes range without glucose-lowering medicines for a sustained period.

Remission is not the same as a guaranteed permanent cure.

The possibility of remission can depend on factors such as how long diabetes has been present, weight changes, insulin production and individual metabolic health.

Even after remission, ongoing health checks remain useful.

Do not automatically take twice the amount at the next dose.

The correct action depends on the medicine and how much time has passed since the missed dose. Different medicines have different instructions.

Check your prescription information or ask your doctor or pharmacist if you are unsure.

If you frequently forget doses, tell your doctor. The problem may be related to your daily routine, meal timings, side effects or the complexity of the prescription.

Sometimes making the treatment simpler can help.

They remain important.

Diabetes medicine is not a replacement for everyday habits that support glucose control.

This does not mean that you have to remove rice completely from your diet.

A meal can include a sensible portion of rice along with vegetables, dal, fish, eggs or another suitable source of protein. The overall portion and balance matter.

Tea with sugar, sweets, fried snacks and large portions can make glucose and weight management harder when consumed frequently.

Physical activity does not have to mean joining a gym. Walking, gardening, household work, field work and other regular movement can contribute to daily activity.

If you use insulin or another medicine that can cause hypoglycaemia, your doctor may advise you about meals, activity and glucose monitoring.

The type and frequency of monitoring depend on the treatment.

Some people need regular finger-prick glucose testing. Others may benefit from continuous glucose monitoring in particular circumstances.

HbA1c provides a longer-term picture of glucose control and is usually checked at intervals decided by the doctor.

Medcare offers continuous glucose monitoring, insulin and diet counselling for appropriate patients.

Monitoring is most useful when the results help answer a clinical question. The goal is not simply to collect more numbers.

Yes.

HbA1c is a very useful test, but certain conditions can affect its interpretation.

The result depends partly on haemoglobin and red blood cell behaviour. Anaemia, recent blood loss, blood transfusion and some haemoglobin variants can affect the relationship between HbA1c and actual glucose levels.

Haemoglobin E trait is one example that may interfere with some HbA1c testing methods.

If your HbA1c does not seem to match your home glucose readings, symptoms or other test results, tell your doctor. The discrepancy may need further assessment.

Tell your doctor about all medicines and supplements you take.

Also mention if you have:

• Kidney disease
• Liver disease
• Heart disease or heart failure
• Frequent urinary or genital infections
• Significant digestive problems
• Previous pancreatitis
• Repeated low blood sugar episodes
• Pregnancy or plans for pregnancy
• Recent unexplained weight loss
• A recent serious illness or hospital admission

Your doctor also needs to know if you are having difficulty taking your current medicines regularly.

These details can influence the treatment choice.

"Insulin damages the kidneys."

No. Insulin does not damage the kidneys simply because it is being used. Poorly controlled diabetes can contribute to kidney damage, while appropriate glucose control can help reduce the effects of prolonged high blood sugar.

"Once I start insulin, I will need it for the rest of my life."

Not always. Some people need insulin temporarily, while others eventually require it long term. The reason insulin was started and how the diabetes changes over time both matter.

"GLP-1 medicines are just slimming injections."

No. They affect glucose regulation as well as appetite and digestion. Some are used for diabetes, while certain medicines or formulations are approved for weight management. They should be used under medical supervision.

"The strongest diabetes tablet is the best one."

No. The best medicine is the one that provides an appropriate balance of glucose control, benefits, risks and practicality for that particular patient.

"If my sugar becomes normal, I can stop the medicine."

No. Normal sugar while taking treatment does not automatically mean that diabetes has disappeared. Any change in treatment should be discussed with your doctor.

Diabetes does not affect only blood glucose.

Over time, high glucose can occur alongside high blood pressure, abnormal cholesterol, excess weight, kidney disease and cardiovascular disease.

This has changed the way doctors think about diabetes medicines.

For some people, an SGLT2 inhibitor may be considered because kidney or heart protection is part of the treatment goal. For others, a GLP-1 receptor agonist or dual GIP/GLP-1 medicine may be considered because weight management and glucose control are both important.

The medicine is therefore selected according to the person's overall risk, not simply the HbA1c number.

Arrange a review if:

• Your glucose readings are repeatedly higher than your usual target
• Your HbA1c has increased
• You are having repeated episodes of low blood sugar
• You are losing weight without trying
• You have persistent vomiting or troublesome digestive symptoms after starting a medicine
• You are developing repeated urinary or genital infections
• You are finding your prescription difficult to follow
• You are unsure whether you should continue a medicine
• You are pregnant or planning pregnancy
• You have developed a new heart or kidney problem

Regular follow-up is useful even when you feel well. Diabetes complications can develop without obvious symptoms.

Get urgent medical help if you develop severe chest pain, severe breathlessness, fainting, confusion, seizure, severe dehydration, persistent vomiting or marked weakness.

Symptoms such as severe abdominal pain, vomiting and dehydration in a person with diabetes can sometimes indicate a serious metabolic problem.

If you think you are having a medical emergency, call 108 or 112.

At Medcare Diabetes & Obesity Clinic, Dr. Das looks at diabetes together with the other factors that commonly affect long-term health, including weight, blood pressure, heart health, thyroid problems and sleep.

The assessment may include HbA1c, ECG, body composition analysis, diabetic foot checks or continuous glucose monitoring when clinically appropriate. HbA1c results are usually available before the patient leaves. Other blood tests can be done at a laboratory of the patient's choice.

For people who need ongoing treatment and follow-up, diabetes care at Medcare covers Type 1 diabetes, Type 2 diabetes and prediabetes.

• Type 2 diabetes does not have one standard medicine plan for everyone.
• Metformin remains a commonly used option, but other medicines may be more appropriate depending on heart, kidney and weight-related factors.
• GLP-1 and dual GIP/GLP-1 medicines may help selected patients with both glucose control and weight management.
• SGLT2 inhibitors can have benefits beyond glucose lowering, particularly for selected people with kidney disease or heart failure.
• Insulin may be temporary or long term. Starting it does not automatically mean that diabetes has become permanently severe.
• Do not stop or change prescription diabetes medicines without speaking to your doctor.