Injectables — insulin and GLP-1 medications for diabetes

About this guide

Two kinds of medication for diabetes are given by injection:

• Insulin — for patients whose own pancreas no longer produces enough insulin to keep glucose in range
• GLP-1 receptor agonists (most of which are injected, though one — Rybelsus — is oral) — which help with both blood sugar control and, for many patients, weight loss

This guide covers both. Starting an injection feels like a big step. In our experience, most patients are pleasantly surprised — modern injection pens are small, the needles are very fine, and once you’ve done the first few, the anxiety fades fast. Starting insulin or a GLP-1 is not a punishment, not a failure of your previous efforts, and not always permanent.

This is the fourth of five short guides:

1. What is diabetes and pre-diabetes?
2. Diet and lifestyle
3. Oral medications (and supplements)
4. Injectables — insulin and GLP-1 medications (you are here)
5. Preventive care for diabetes

Why your doctor might suggest an injection

There are two main reasons:

1. Your oral medications aren’t enough. Type 2 diabetes is progressive — over the years, the pancreas produces less and less insulin on its own, and at some point even well-chosen oral medications can’t keep HbA1c in range.
2. A different benefit is needed. GLP-1s, for example, produce meaningful weight loss and reduce cardiovascular events. For some patients, the injection is chosen earlier in the course of treatment for those additional benefits, not because the orals have “failed.”

Insulin is sometimes the right choice from the very beginning — for example, when blood sugars are very high (HbA1c >9–10%) with symptoms, or if there has been unexplained weight loss. It can also be temporary: if insulin is started during a crisis, patients often step back down to oral treatment once things are controlled.

Injectable GLP-1 receptor agonists

GLP-1 agonists increase insulin release after meals (when blood sugar rises), slow stomach emptying, and reduce appetite. They also reduce the risk of heart attack, stroke, and kidney disease in patients with or at high risk of these complications.

Injectables available in Singapore include:

• Semaglutide (Ozempic) — once weekly, for Type 2 diabetes. Available in 0.25 mg, 0.5 mg, and 1 mg pre-filled pens. The same molecule, at higher weight-loss-specific doses (1.7 mg and 2.4 mg), is registered in Singapore as Wegovy for weight management — though Wegovy is not reimbursed for diabetes alone and is typically self-funded.
• Dulaglutide (Trulicity) — once weekly, pre-filled single-use pen. Registered in Singapore; less commonly prescribed at KTMC but used by some practices.
• 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 in the first few weeks and at each dose increase. Usually settles. Helpful: smaller portions, avoid greasy or fried food, eat slowly, stop eating when the “enough” signal arrives. Most patients also find they simply feel less hungry — and less interested in heavy or sweet foods.
• Reduced appetite and weight loss — usually welcome.
• Gastrointestinal effects — bloating, indigestion, occasional vomiting.
• Constipation — some patients; plenty of water, fibre-rich food, and gentle movement helps.
• Rarely, pancreatitis — severe, constant upper-abdominal pain, often with vomiting. Stop the drug and contact us or A&E urgently.
• Gallstones / gallbladder disease — small increased risk with significant weight loss.
• Before surgery or anaesthesia: the delayed stomach emptying can be a concern. Let your anaesthetist know you are on a GLP-1; some may ask you to hold a dose before certain procedures.

GLP-1s don’t cause low blood sugars on their own — but the risk goes up if you are also taking a sulfonylurea or insulin. Your doctor may reduce those when starting a GLP-1.

Basal insulin — the slow, steady background

“Basal insulin” is a once-daily (or occasionally twice-daily) long-acting insulin that keeps your blood glucose steady between meals and overnight. It is the most common first insulin prescribed in Type 2 diabetes.

Types available in Singapore as at 2026:

If you are currently on a different basal insulin from what’s listed above, we will guide you through any switch — the options above are what we most commonly prescribe.

How your dose is set

• Starting dose is usually 0.1–0.2 units per kg of body weight per day, given at a consistent time (often before bed for once-daily long-acting types).
• Titration means gradually adjusting the dose based on your morning fasting blood sugar — typically adding 2 to 4 units every 3 to 4 days until the fasting sugar is in target range.
• We’ll teach you how to do this at home, and you’ll record your readings so we can review them together.
• If fasting sugars hit target but HbA1c is still above target (because of high post-meal spikes), or if your basal dose starts exceeding about 0.5 units/kg/day, we may add a mealtime (“bolus”) insulin or switch to a more comprehensive regimen.

How to inject — the basics

Modern insulin and GLP-1 injections are subcutaneous — into the fatty tissue just under the skin, not into muscle. A few things make a big difference:

Where to inject

• Best areas: lower abdomen (not within 2 cm of the navel), the upper outer thighs, and the upper outer arms (or buttocks).
• Keep to one body area for any given type of insulin — absorption rates differ between abdomen, thigh, and arm, and switching around can make blood sugars unpredictable.
• Rotate within the area — move a thumb’s width to the side each injection. Repeatedly injecting in the exact same spot can cause lipohypertrophy — lumps of thickened fatty tissue that absorb insulin erratically. If you have these (or suspect them), tell us.

Avoid

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

Technique

• Clean hands; no need to wipe the skin with alcohol routinely (it can sting and dry the skin).
• Insert perpendicularly (90°) with most modern short pen needles (4, 5, 6 mm). Pinching the skin is usually not necessary at these needle lengths except in very thin patients.
• Push the plunger fully in, hold for about 10 seconds, then remove — this ensures the full dose has been delivered.
• A tiny drop of blood is normal occasionally; gentle pressure with a tissue is enough.
• Do not massage the injection site afterwards — it can change absorption.
• Let cold insulin warm slightly before injecting — injecting ice-cold insulin straight from the fridge is more painful.

Disposing of used needles

• Into a sharps container (rigid plastic, metal, or a purpose-made container with a secured lid).
• Do not reuse needles — they dull, distort, and become more painful and more prone to causing lipohypertrophy.
• Your pharmacy can usually advise on proper sharps disposal in Singapore.

Storing your insulin and GLP-1 pens

This is where a lot of preventable problems start.

Unopened pens and vials

• In the fridge, between 2°C and 8°C — not in the freezer, not next to the freezer panel, not in the door (which fluctuates too much).
• If you find frozen insulin, do not use it — freezing damages the protein. Call your pharmacy for a replacement.

Once opened (in use)

• Most opened insulin and GLP-1 pens can be kept at room temperature below 30°C for 28 days — but this varies by product (some are 4 weeks, some 6, some 8). Always check the leaflet for the specific product.
• Once past the in-use duration, discard — even if the pen has insulin left.
• Do not put the in-use pen back in the fridge and then out again repeatedly — pick one approach per pen.

General rules

• Keep away from direct sunlight and heat — don’t leave 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 if there is clumping, frosting, colour change, or you’re not sure.

Travelling with injectables

Travel is completely compatible with being on insulin or a GLP-1. A few practical steps:

Before you travel

• Get a travel letter from us stating your medical condition and listing your medications, including the injectables. Bring it with you — this helps at airport security and with customs if asked. Just let our reception know in advance of your trip.
• Pack enough medication for your trip plus at least a week extra — in case of delays or lost luggage.
• Keep your medications in their original packaging with labels intact. This also helps at customs.

Flying

• Insulin and GLP-1 pens always go in your hand-carry luggage, never in checked-in baggage. Temperatures in the aircraft hold can drop below freezing, which damages the drug.
• Pack in an insulated pouch with a small cold pack (gel, not loose ice) for long journeys. Ensure the insulin does not touch the cold pack directly — you don’t want to freeze it.
• Most airport security will allow insulin pens, needles, glucose tabs, and a small sharps container through with the travel letter.
• Keep glucose tabs or a sugary snack in your hand luggage for low blood sugars, especially if you’re on insulin or a sulfonylurea.

Time zone changes

• Short trips (less than 2 hours difference) — usually no change needed.
• Longer trips — basal insulin and once-weekly GLP-1 doses may need adjusting.
• Please see us a couple of weeks before the trip if you’re changing more than 3 time zones. We’ll work out a specific plan.

At your destination

• Store pens according to the same rules (fridge for unopened; below 30°C for in-use).
• Hot climates and no fridge? Insulated pouches like the Frio (works on evaporative cooling) keep pens safe for multi-day trips without a fridge.
• Don’t freeze.

Ramadan — fasting safely with diabetes

Many Muslim patients with diabetes wish to fast during Ramadan. It is possible to do so safely for many patients — but not for everyone, and planning ahead matters. We recommend that you see us a few weeks before Ramadan starts to review.

Risk categories

International diabetes groups (IDF-DAR) classify patients into risk levels. Broad summary:

• Very high risk — strong recommendation not to fast: recent severe hypoglycaemia or hypoglycaemic unawareness, severe hyperglycaemia (HbA1c >10% or frequent ketosis), pregnancy with pre-existing diabetes, on dialysis, or unstable cardiovascular disease.
• High risk — recommend not to fast (discuss carefully): HbA1c 8.6–10%, advanced kidney disease, on insulin with less-than-ideal control, older age with multiple comorbidities.
• Moderate / low risk — can fast with planning: well-controlled Type 2, on lifestyle alone, metformin, DPP-4 inhibitor, low-dose SGLT2, or low-dose once-daily basal insulin with good history.

If you do fast

• Adjust your insulin dose: typically, the basal insulin dose is reduced by 15–30% at pre-dawn (suhoor), depending on the regimen.
• Short-acting insulin / sulfonylurea at meals: the larger meal is usually at the evening break-of-fast (iftar), so we often reverse the usual pattern — the larger dose goes with iftar, and a smaller dose (sometimes none) with suhoor.
• GLP-1 agonists — less dosing adjustment usually needed; many patients continue as usual.
• Home glucose monitoring — check more often during Ramadan, especially in the early days. Low sugar readings during fasting hours mean you should break the fast.
• Hydration — drink plenty of water during the permitted hours. Dehydration raises risk on SGLT2 inhibitors and causes symptomatic hypoglycaemia.
• Break the fast immediately if you develop 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. The usual sweet iftar foods (dates, sugary drinks) should be in small amounts, not large.

Your Ramadan plan, in our clinic

If you are planning to fast, please book a pre-Ramadan consultation. We’ll go through:

1. Your risk category and whether it’s safe to fast this year
2. Dose adjustments to your current insulin / GLP-1 / oral medications
3. What symptoms should prompt breaking the fast
4. Home glucose monitoring frequency
5. When to contact us during Ramadan if something isn’t going well

Hypoglycaemia — recognising and treating low blood sugar

Low blood sugar (under 4 mmol/L) is a risk mainly for patients on insulin or sulfonylureas. GLP-1 agonists on their own don’t cause hypos, but the risk rises when they are combined with insulin or a sulfonylurea.

Symptoms

Early (sympathetic, adrenaline-driven):

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

Later (brain running out of glucose):

• Confusion, slurred speech
• Decreased concentration or memory
• Unsteady walk, blurred vision
• Eventually: unconsciousness, seizure

Treat low sugar early — the 15-15 rule

If you have symptoms and a reading under 4 mmol/L (or if you have symptoms and can’t check):

1. Eat or drink 15 g of fast-acting carbohydrate. Options:
   • 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 — chocolate has fat, which slows absorption)
2. Wait 15 minutes. Recheck your blood sugar.
3. If still under 4 mmol/L, repeat another 15 g of carbohydrate.
4. Once you’re above 4 mmol/L, eat a small snack or meal — especially if the next meal is more than an hour away. This stops the drop from coming back.

Severe hypoglycaemia

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

• Do not try to 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 patients on long-term insulin stop getting the early warning symptoms — they go straight from feeling fine to confused or unwell. This is dangerous and is a reason to see us promptly. We’ll typically raise your blood sugar targets for a few weeks (allowing the warning signals to return), review your medications, and sometimes arrange continuous glucose monitoring.

What’s next

The last guide in this series covers the regular checks and preventive care that catch problems early and keep you well — eye, foot, kidney, heart, mood, vaccinations, and routine blood tests:

→ Preventive care for diabetes

Get in touch

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

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

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.

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. v1.0 · April 2026 · Review due April 2028.