GLP-1 Medication

What is glp-1 medication?

GLP-1 (glucagon-like peptide-1) medications are prescription treatments used for type 2 diabetes and chronic weight management.

GLP-1 is a hormone released naturally after meals. It helps to:

• Signal fullness to the brain
• Slow gastric emptying
• Regulate blood sugar levels

GLP-1 receptor agonists mimic this hormone, reducing appetite and improving glucose control. Some newer medications act on additional hormone pathways involved in metabolic regulation.

In individuals living with obesity, GLP-1 medications may support weight loss when prescribed and used under medical supervision.

Types of GLP-1 medication

Several GLP-1 medications are available in Singapore. The most commonly prescribed include:

Ozempic

• Once a week subcutaneous injection
• Approved by HSA for type 2 diabetes
• May be prescribed off-label for weight management

Active ingredient: semaglutide

Ozempic was originally developed for diabetes. Because it reduces appetite and improves blood sugar control, weight loss was also observed in clinical studies.

Ozempic contains the same active ingredient as Wegovy but is typically prescribed at lower maximum doses for diabetes management.

Wegovy

• Once a week subcutaneous injection
• Approved by HSA for chronic weight management

Active ingredient: semaglutide (higher-dose formulation)

Wegovy contains the same active ingredient as Ozempic, but at a higher dose specifically studied and approved for weight management.

Mounjaro

• Once a week subcutaneous injection
• Dual GIP and GLP-1 receptor agonist
• Approved by HSA for type 2 diabetes

Active ingredient: tirzepatide

Mounjaro acts on two hormone pathways, GLP-1 and GIP. In clinical trials, tirzepatide demonstrated greater average weight reduction of 15–20% compared to earlier GLP-1 medications under controlled study conditions.

Saxenda

• Once daily subcutaneous injection
• Approved by HSA for chronic weight management

Active ingredient: liraglutide

Saxenda is an earlier-generation GLP-1 medication. Because it is administered daily, some patients may prefer weekly alternatives. Average weight reduction in studies has generally ranged between 5–10% when combined with lifestyle changes.

What’s the difference between Ozempic, Wegovy, Mounjaro and Saxenda?

Although all are used in medical weight management, they differ in active ingredient, dosing schedule, approved indications, and degree of weight loss observed in clinical studies.

Key differences at a glance

* Results vary between individuals and depend on adherence and lifestyle factors.

There is no single “best” option. Suitability depends on:

• Your BMI and medical conditions
• Whether you have diabetes
• Tolerability and side-effect profile
• Lifestyle preferences, such as daily vs weekly injections
• Cost considerations
• Long-term treatment goals

Your doctor will assess your individual health profile before recommending the most appropriate option.

Why do you need GLP-1 medication?

GLP-1 medication may be considered if:

• Your BMI is ≥ 30 kg/m²
• Your BMI is ≥ 27 kg/m² with obesity-related conditions such as:
  • Type 2 diabetes
  • High blood pressure (hypertension)
  • Abnormal cholesterol (dyslipidaemia)
  • Obstructive sleep apnoea (OSA)
• You have difficulty achieving or maintaining weight loss with lifestyle changes alone

Obesity is recognised as a chronic condition influenced by hormonal, metabolic and genetic factors. GLP-1 medications may help regulate appetite and improve metabolic control as part of medical management.

Who should not take GLP-1 medication?

GLP-1 medications are not suitable for everyone. They are not recommended if you:

• Are pregnant, trying to conceive, or breastfeeding
• Have a personal or family history of medullary thyroid cancer (MTC)
• Have multiple endocrine neoplasia type 2 (MEN2)
• Have had a severe allergic reaction to a GLP-1 medication

Your doctor will also assess suitability carefully if you have:

• A history of pancreatitis
• Gallbladder disease
• Significant gastrointestinal conditions
• Kidney impairment (risk of dehydration if vomiting/diarrhoea occurs)
• Certain eye conditions related to diabetes (monitoring may be needed)

What are the risks and complications of GLP-1 medication?

Many patients tolerate GLP-1 medications well. Most side effects are gastrointestinal and are more common when starting treatment or increasing dosage.

Common side effects

• Nausea
• Vomiting
• Diarrhoea
• Constipation
• Abdominal discomfort and/or bloating
• Reduced appetite

These are usually mild and improve over time, especially with gradual dose escalation and dietary adjustments.

Less common but important risks

• Pancreatitis (seek medical attention for severe, persistent abdominal pain)
• Gallstones or gallbladder inflammation
• Worsening of diabetic retinopathy in some patients
• Dehydration, especially if vomiting or diarrhoea occurs

Your doctor will counsel you on the warning signs and appropriate monitoring during treatment.

How do you prepare for GLP-1 medication?

Before starting treatment, your doctor will:

• Review your medical history and current medications
• Assess BMI, body composition, and weight history
• Screen for underlying metabolic conditions
• Check baseline measurements such as blood pressure and relevant blood tests (e.g. glucose, HbA1c, lipids, kidney function), where appropriate
• Discuss expected benefits, side effects, dosing schedule, and contraindications

You will also be advised on:

• How to administer the medication
• Practical steps to reduce side effects, such as:
  • Eating smaller meals
  • Maintaining adequate hydration
  • Avoiding heavy or fatty meals during dose increases

What can you expect with GLP-1 medication?

How is it administered?

Most GLP-1 medications for weight management are given as subcutaneous injections using a pen device:

• Weekly injections: Ozempic, Wegovy, Mounjaro
• Daily injections: Saxenda

Injections are typically given into the:

• Abdomen
• Thigh
• Upper arm

Patients will be taught how to self-administer safely.

How soon do effects start?

Some patients notice reduced appetite within the first few weeks. Weight change is usually gradual over several months and varies between individuals.

How long is the course of treatment?

The duration of treatment depends on:

• Your response to the medication
• Any side effects experienced
• Your long-term weight management plan

Some patients may require longer-term therapy to maintain results.

Care and recovery after GLP-1 medication

There is no “recovery period” in the traditional sense, but ongoing monitoring is important.

For patients on Parkway Shenton’s medical weight management programme, your doctor will schedule follow-up visits every 2–3 months initially to:

• Assess tolerability and side effects
• Adjust dosage, if needed
• Monitor weight and metabolic markers, where appropriate
• Review any interactions with other medications (e.g. insulin or sulfonylureas in patients with diabetes)

Once your condition is stable, follow-up visits may be reduced to every 6 months.

If GLP-1 medication is stopped, appetite may return and some weight regain can occur. Your doctor can advise on next steps and long-term strategies based on your individual situation.