Injectables — insulin and GLP-1 medications for diabetes

In brief

• Insulin and most GLP-1 medicines are injected; starting one is not a failure, and not always permanent.
• GLP-1 injections are usually once weekly; nausea is common at first and usually settles.
• Basal insulin starts once daily at a low dose, adjusted every 3 to 4 days by your morning fasting sugar.
• Keep unopened pens in the fridge at 2°C to 8°C; most opened pens keep below 30°C for 28 days.
• For a sugar under 4 mmol/L, take 15 g of fast-acting sugar and recheck after 15 minutes; call 995 if someone is unresponsive.
• Not everyone can fast safely in Ramadan, so see us a few weeks before it starts.

We start and adjust insulin and GLP-1 treatment at our Punggol clinic, including travel and Ramadan plans. See our chronic disease care.

Diabetes series: 1. What is diabetes · 2. Diet and lifestyle · 3. Oral medications · 4. Injectables · 5. Preventive care

Why your doctor might suggest an injection

Starting an injection feels like a big step, but modern pens are small and the needles are very fine. In our experience, the anxiety fades after the first few. Starting insulin or a GLP-1 is not a punishment or a failure, and it is not always permanent.

There are two main reasons:

1. Your oral medications aren’t enough. Type 2 diabetes is progressive. Over the years the pancreas makes less insulin, and eventually even well-chosen tablets can’t keep HbA1c in range.
2. A different benefit is needed. GLP-1s produce meaningful weight loss and reduce cardiovascular events. Some people start one early for these benefits, not because tablets have “failed”.

Insulin is sometimes right from the start, for example when blood sugar is very high (HbA1c >9–10%) with symptoms, or after unexplained weight loss. It can also be temporary: if started during a crisis, people often step back down to tablets once things are controlled.

Injectable GLP-1 receptor agonists

GLP-1 agonists increase insulin release after meals, slow stomach emptying and reduce appetite. They also lower the risk of heart attack, stroke and kidney disease in people who have, or are at high risk of, these complications. Most are injected; semaglutide also comes as a tablet (Rybelsus).

Injectables available in Singapore include:

• Semaglutide (Ozempic): once weekly for Type 2 diabetes, in 0.25 mg, 0.5 mg and 1 mg pre-filled pens. At higher doses (1.7 mg and 2.4 mg), the same molecule is registered in Singapore as Wegovy for weight management. Wegovy is not reimbursed for diabetes alone and is usually self-funded.
• Dulaglutide (Trulicity): once weekly, in a single-use pre-filled pen. Registered in Singapore; we prescribe it less often, but some practices use it.
• Tirzepatide (Mounjaro): once weekly, a dual GLP-1 / GIP receptor agonist. Registered in Singapore; availability, cost and prescribing vary between clinics.

Side effects to expect and manage

• Nausea is the most common, especially early on and after each dose increase. It usually settles. Eat smaller portions slowly, avoid greasy or fried food, and stop when you feel full. Most people also feel less hungry and less drawn to heavy or sweet foods.
• Reduced appetite and weight loss: usually welcome.
• Other stomach effects: bloating, indigestion, occasional vomiting.
• Constipation in some people. Water, fibre-rich food and gentle movement help.
• Pancreatitis (rare): severe, constant upper-abdominal pain, often with vomiting. Stop the drug and contact us or A&E urgently.
• Gallstones or gallbladder disease: a small increased risk with significant weight loss.
• Before surgery or anaesthesia: slower stomach emptying can be a concern. Tell your anaesthetist you take a GLP-1; you may be asked to hold a dose before certain procedures.

GLP-1s don’t cause low blood sugar on their own. The risk rises if you also take a sulfonylurea or insulin, so your doctor may reduce those when you start a GLP-1.

Basal insulin — the slow, steady background

Basal insulin is long-acting, given once a day (occasionally twice). It keeps blood glucose steady between meals and overnight, and is the most common first insulin in Type 2 diabetes.

Types available in Singapore as at 2026:

These are the ones we most often prescribe. If you are on a different basal insulin, we will guide you through any switch.

How your dose is set

• Starting dose: usually 0.1–0.2 units per kg of body weight per day, at a consistent time (often before bed for once-daily long-acting types).
• Titration: typically add 2 to 4 units every 3 to 4 days, based on your morning fasting blood sugar, until it is in the target range. We teach you to do this at home and review your readings together.
• Adding mealtime insulin: if fasting sugars reach target but HbA1c stays high (because of after-meal spikes), or your basal dose goes above about 0.5 units/kg/day, we may add a mealtime (“bolus”) insulin or switch to a fuller regimen.

How to inject — the basics

Insulin and GLP-1 injections are subcutaneous: into the fatty tissue just under the skin, not into muscle.

Where to inject

• Best areas: the lower abdomen (not within 2 cm of the navel), upper outer thighs, and upper outer arms or buttocks.
• Keep to one body area for each type of insulin. Absorption differs between abdomen, thigh and arm, so switching can make blood sugar unpredictable.
• Rotate within the area, moving a thumb’s width each time. Repeated injections in one spot can cause lipohypertrophy: lumps of thickened fat that absorb insulin erratically. Tell us if you have, or suspect, these lumps.

Avoid

• Bruises, scar tissue, skin folds and areas close to joints
• The groin and the area right around the navel
• Inflamed or irritated skin

Technique

• Clean hands. You don’t need to wipe the skin with alcohol routinely; it can sting and dry the skin.
• Insert at 90° with most modern short pen needles (4, 5 or 6 mm). You usually don’t need to pinch the skin, unless you are very thin.
• Push the plunger fully in and hold for about 10 seconds before removing, so the full dose goes in.
• An occasional tiny drop of blood is normal. Press gently with a tissue.
• Don’t massage the site afterwards, as it can change absorption.
• Let cold insulin warm slightly first. Ice-cold insulin straight from the fridge hurts more.

Disposing of used needles

• Use a sharps container: rigid plastic, metal or a purpose-made container with a secure lid.
• Don’t reuse needles. They blunt and bend, hurt more and make lipohypertrophy more likely.
• Your pharmacy can advise on sharps disposal in Singapore.

Storing your insulin and GLP-1 pens

Unopened pens and vials

• Keep them in the fridge at 2°C to 8°C: not in the freezer, beside the freezer panel or in the door, where the temperature fluctuates too much.
• Never use insulin that has frozen, as freezing damages the protein. Call your pharmacy for a replacement.

Once opened (in use)

• Most opened insulin and GLP-1 pens keep at room temperature below 30°C for 28 days. Some last 4 weeks, some 6, some 8, so check the leaflet.
• Discard the pen once past its in-use period, even if insulin is left.
• Don’t keep moving an in-use pen in and out of the fridge. Pick one approach per pen.

General rules

• Keep pens away from direct sunlight and heat: not in a parked car, on a windowsill or next to the stove.
• Inspect before each use. The long-acting insulins used here (glargine, degludec) should look clear. Discard the pen if it shows clumping, frosting or colour change, or if you’re unsure.

Travelling with injectables

Before you travel

• Ask our reception for a travel letter before your trip. It lists your condition and medications, including injectables, and helps at airport security and customs.
• Pack at least a week of extra medication, in case of delays or lost luggage.
• Keep medications in their original labelled packaging, which also helps at customs.

Flying

• Carry insulin and GLP-1 pens in your hand luggage, never in checked baggage. The aircraft hold can drop below freezing, which damages the drug.
• On long journeys, use an insulated pouch with a small gel cold pack (not loose ice). Don’t let the pens touch the cold pack, or they may freeze.
• Most airport security will allow insulin pens, needles, glucose tablets and a small sharps container with the travel letter.
• Keep glucose tablets or a sugary snack in your hand luggage, especially if you take insulin or a sulfonylurea.

Time zone changes

• Up to 2 hours’ time difference: usually no change needed.
• More than 2 hours’ difference: basal insulin and once-weekly GLP-1 doses may need adjusting. See us a couple of weeks before the trip, and we will work out a plan.

At your destination

• Store pens by the same rules: fridge for unopened, below 30°C for in use.
• Hot climate and no fridge? Insulated pouches such as Frio, which cool by evaporation, keep pens safe for multi-day trips.
• Don’t freeze them.

Ramadan — fasting safely with diabetes

Many Muslim patients with diabetes wish to fast during Ramadan. Many can do so safely, but not everyone, so planning matters. See us a few weeks before Ramadan starts.

Risk categories

International diabetes groups (IDF-DAR, 2021) use a points score. It counts factors such as the type and duration of your diabetes, past hypos, your HbA1c, your medications, home glucose checks, recent diabetes emergencies, heart and kidney disease, pregnancy, frailty, physical work, how previous Ramadans went and the length of the fast. The total puts you in one of three groups:

• Low risk (0 to 3 points) — fasting is probably safe, with a medical review, medication changes and careful glucose monitoring.
• Moderate risk (3.5 to 6 points) — fasting safety is uncertain. The same steps apply, and we discuss carefully whether fasting is wise for you.
• High risk (more than 6 points) — fasting is probably unsafe, and we advise against it. Some factors score enough on their own: hypoglycaemia unawareness, unstable heart or blood-vessel disease, an eGFR below 30, frailty or impaired thinking, or pregnancy with sugars above target.

If you do fast

• Adjust your insulin: once-daily basal insulin is usually taken at iftar, the evening meal that breaks the fast, with the dose reduced by 15–30%. Twice-daily and premixed insulins need different changes, which we plan with you.
• Short-acting insulin or a sulfonylurea at meals: the larger meal is usually iftar. So we often reverse the usual pattern, with the larger dose at iftar and a smaller dose (sometimes none) at suhoor, the pre-dawn meal.
• GLP-1 agonists usually need less adjustment, and many people continue as usual.
• Check your glucose at home more often, especially in the early days. A low reading during fasting hours means you should break the fast.
• Drink plenty of water in the permitted hours. Dehydration can cause dizziness and low blood pressure, especially if you take an SGLT2 inhibitor.
• Break the fast immediately if you have symptoms of low blood sugar, very high blood sugar with symptoms, or feel unwell.
• Eat a balanced suhoor: slow-release carbohydrate (brown rice, oats, wholemeal bread), protein and plenty of water. Keep sweet iftar foods such as dates and sugary drinks to small amounts.

Your Ramadan plan, in our clinic

If you plan to fast, book a pre-Ramadan consultation. We will go through:

1. Your risk category, and whether it is safe to fast this year
2. Dose changes to your insulin, GLP-1 or oral medications
3. Symptoms that mean you should break the fast
4. How often to check your glucose at home
5. When to contact us during Ramadan

Hypoglycaemia — recognising and treating low blood sugar

Low blood sugar (under 4 mmol/L) is mainly a risk with insulin or sulfonylureas. GLP-1 agonists alone don’t cause hypos, but add to the risk when combined with these.

Symptoms

Early (adrenaline-driven):

• Shakiness, sweating, palpitations
• Hunger, tingling around the mouth
• Anxiety, irritability
• Tiredness or feeling “off”

Later (the brain running out of glucose):

• Confusion, slurred speech
• Poor concentration or memory
• Unsteady walk, blurred vision
• Eventually, unconsciousness or a seizure

Treat low sugar early — the 15-15 rule

If you have symptoms and a reading under 4 mmol/L, or symptoms and no way to check:

1. Eat or drink 15 g of fast-acting carbohydrate, such as:
   • 3 teaspoons of sugar or glucose powder (Glucolin is widely available)
   • ½ cup (120 ml) of fruit juice or regular soft drink
   • 3–4 glucose tablets
   • 3 sweets (not chocolate, whose fat slows absorption)
2. Wait 15 minutes, then recheck your blood sugar.
3. If it is still under 4 mmol/L, take another 15 g.
4. Once above 4 mmol/L, eat a small snack or meal, especially if your next meal is more than an hour away. This stops the sugar dropping again.

Severe hypoglycaemia

If someone with diabetes is unresponsive, having a seizure or unable to swallow:

• Don’t give anything by mouth (choking risk).
• Call 995 for an ambulance.
• If you have a glucagon kit (nasal or injected) and have been trained, use it now.

Hypoglycaemia unawareness

Some people on long-term insulin stop getting the early warning symptoms. They go straight from feeling fine to confused or unwell. This is dangerous; see us promptly. We usually raise your blood sugar targets for a few weeks so the warning signs can return. We also review your medications and sometimes arrange continuous glucose monitoring.

What’s next

The last guide in this series covers the regular checks that catch problems early: eyes, feet, kidneys, heart, mood, vaccinations and routine blood tests.

→ Preventive care for diabetes

Get in touch

Punggol — 658 Punggol East, #01-04, Singapore 820658 · Tel 6312 4589

Joo Chiat — 172 Joo Chiat Road, #01-01, Singapore 427443 · Tel 6920 1952

Email — admin@ktmc.sg

References

• Agency for Care Effectiveness (ACE). Initiating basal insulin in type 2 diabetes mellitus. Updated November 2024. ace-hta.gov.sg
• Agency for Care Effectiveness (ACE). Oral glucose-lowering agents in type 2 diabetes mellitus — an update. Updated August 2017.
• International Diabetes Federation — Diabetes and Ramadan (IDF-DAR). Practical Guidelines for Diabetes Management During Ramadan. 2021 edition. idf.org
• American Diabetes Association. Standards of Care in Diabetes — 2026.
• Nakhleh A, et al. Safety and effectiveness of sodium-glucose co-transporter 2 inhibitors on glycemic control in patients with type 2 diabetes mellitus fasting during Ramadan: a review. Clinical Medicine Insights: Endocrinology and Diabetes 2024. pmc.ncbi.nlm.nih.gov

This information is for general education only and is not a substitute for medical advice. Insulin, GLP-1 dosing, and Ramadan adjustments must be individualised — please book a consultation before making any changes to your regimen. v1.1 · October 2026 (v1.0 April 2026) · Review due April 2028.