What is diabetes and pre-diabetes?

About this guide

If you’ve just been told you have diabetes or pre-diabetes, this guide is the place to start. Diabetes affects roughly 1 in 10 Singaporeans and that number is growing — which is why the Ministry of Health launched the War on Diabetes national programme back in 2016.

Diabetes is manageable. It is not a punishment, not your fault, and not something you have to figure out alone. Most of what determines how well you live with diabetes is about consistent, unglamorous daily habits — and a care team you trust.

This is the first of five short guides we give our diabetes patients:

1. What is diabetes and pre-diabetes? (you are here) — the basics: types, numbers, risks, symptoms
2. Diet and lifestyle for diabetes and pre-diabetes — the foundation of treatment
3. Oral medications for diabetes (and what about supplements?) — metformin, SGLT2 inhibitors, DPP-4 inhibitors, sulfonylureas, and the supplement question
4. Injectables — insulin and GLP-1 medications — how they work, how to use them safely, Ramadan, travel, and storage
5. Preventive care for diabetes — eye, foot, kidney, heart, mood, vaccines, and the regular checks that catch problems early

What is diabetes?

Diabetes is a long-term condition where the level of sugar (glucose) in your blood is too high. Glucose comes from the food you eat — mostly from carbohydrates (rice, noodles, bread, potatoes, sugar, fruit) — and is your body’s main source of energy.

After a meal, your pancreas releases a hormone called insulin. Insulin is a key that unlocks your cells so glucose can enter and be used for energy. When insulin isn’t doing its job well, glucose stays in the blood instead of moving into cells. Over time, high glucose damages blood vessels and nerves — which is why diabetes is taken seriously.

Two broad things can go wrong:

• The body doesn’t respond well to insulin (insulin resistance) — the “key” still works, but the “lock” has become rusty, so more and more insulin is needed to do the same job.
• The body doesn’t make enough insulin — the cells in the pancreas that produce insulin (beta cells) slow down or stop.

Different types of diabetes reflect different combinations of these problems.

The main types of diabetes

Type 2 diabetes

By far the most common — it makes up about 90% of diabetes in Singapore. Type 2 develops gradually over years, starting with insulin resistance and slowly progressing as the pancreas struggles to keep up. It tends to come with other “metabolic” problems: higher blood pressure, higher cholesterol, and extra weight around the waist.

Type 2 is strongly influenced by diet, physical activity, and weight — but it also has a significant genetic component. Many of our patients have done everything right and still get it because their family history puts them at higher risk. If that’s you, it’s not your fault.

Most of this guide, and the four that follow, focus on Type 2.

Type 1 diabetes

A smaller number of patients have Type 1 diabetes — the body’s immune system destroys the insulin-producing cells, usually early in life. People with Type 1 need insulin from diagnosis onward. In Singapore, Type 1 is usually followed by an endocrinologist, and primary-care clinics like ours support the day-to-day care.

Gestational diabetes

Gestational diabetes (GDM) is diabetes identified during pregnancy — usually in the second or third trimester — because pregnancy hormones naturally increase insulin resistance. It is common in Singapore: about 1 in 4 to 5 pregnant women here develop GDM, a higher rate than in Western populations.

In current practice, all women are screened for GDM at 24 to 28 weeks of pregnancy using a 3-point 75 g oral glucose tolerance test. Women at higher baseline risk (including pre-pregnancy BMI ≥23 kg/m², previous GDM, PCOS, older maternal age, or a strong family history of diabetes) are also screened earlier, in the first trimester, to pick up pre-existing diabetes.

GDM is managed during the pregnancy by the obstetric team, usually with lifestyle intervention and sometimes insulin. After delivery, blood sugars often return to normal — but the future risk is significant:

• Women who’ve had GDM are about 10 times more likely to develop Type 2 diabetes later in life.
• About 4 in 10 women with a history of GDM develop Type 2 diabetes or pre-diabetes within 4 to 6 years after delivery.

If you’ve had GDM, please come in for a follow-up 75 g OGTT 6 to 12 weeks after delivery, and continue annual screening from then on. Lifestyle changes before any future pregnancy also meaningfully reduce the risk of GDM recurring or progressing to Type 2.

What is pre-diabetes?

Pre-diabetes is the stage before Type 2 diabetes fully develops. Your blood sugar is higher than normal but not yet high enough to be called diabetes. It’s a warning signal — and an opportunity.

Pre-diabetes is much more common than diabetes itself. In Singapore, about 14% of adults have it, and many don’t know. Without any intervention, at least 35% of people with pre-diabetes will progress to Type 2 diabetes within eight years. With good lifestyle changes — and occasionally medication — that risk can be cut by roughly a third.

We take pre-diabetes as seriously as we take early diabetes. If we’ve told you that you have pre-diabetes, think of it as a fork in the road rather than bad news.

Your numbers — what they mean

Three blood tests are used most in clinic:

Fasting plasma glucose (FPG)

Measured from a blood sample taken after you haven’t eaten for 8 hours.

Oral glucose tolerance test (OGTT) — 2-hour post-load

You drink a standard glucose drink, wait 2 hours, and blood is taken. Often used when we want to pick up pre-diabetes that FPG alone might miss.

HbA1c (glycated haemoglobin)

HbA1c reflects your average blood glucose over the previous 2 to 3 months. Unlike FPG or OGTT, it doesn’t require fasting or a special drink — it’s a convenient “snapshot” of long-term control.

In Singapore, HbA1c can be used both to screen for and to diagnose diabetes:

HbA1c is also the main tool for tracking long-term control once diabetes is established.

Pre-diabetes is still diagnosed with FPG or OGTT (an HbA1c in the 6.1–6.9% range prompts those further tests to clarify).

When HbA1c may not be reliable

Certain conditions can make HbA1c falsely high or low. In these situations, we’ll usually use FPG or OGTT instead:

• Thalassaemia or other haemoglobin variants (thalassaemia affects about 4% of the Singapore population)
• Iron, vitamin B12, or folate deficiency
• Recent blood transfusion or significant blood loss
• Chronic kidney or liver disease
• Pregnancy (HbA1c tends to read low due to increased red blood cell turnover — OGTT is used instead)

When your numbers don’t agree

Sometimes the FPG and HbA1c tell slightly different stories — for example, a normal FPG but an HbA1c of 6.5%. In these cases, we’ll usually repeat the test (to rule out lab variation or a transient change) and often add an OGTT to see how your body handles a sugar load in real time. The extra test is a small inconvenience but makes the diagnosis more confident.

Rarer forms of diabetes

Most adults diagnosed with high blood sugar have Type 1 or Type 2 diabetes. Occasionally, something less common turns up:

• MODY (Maturity-Onset Diabetes of the Young) — a group of genetic conditions that can look like Type 2 diabetes but often appear in younger people with a strong family history, and may respond to specific treatments.
• Type 3c diabetes — diabetes caused by damage to the pancreas (from chronic pancreatitis, pancreatic surgery, or other pancreatic disease).
• LADA (Latent Autoimmune Diabetes in Adults) — a slow-developing Type 1-like form that appears in adulthood and is often initially misdiagnosed as Type 2.

If the typical pattern doesn’t fit — for example, a lean young adult with sudden high sugars, a first-degree relative diagnosed before age 25, or Type 2 that responds unusually to standard treatment — we may arrange additional blood tests such as C-peptide, diabetes-related autoantibodies, or occasionally genetic testing. The treatment can differ significantly, so getting the diagnosis right matters.

Your personal HbA1c target

A common target is below 7.0%, but your doctor should set a target that fits you:

• Younger adults with newly-diagnosed diabetes who are otherwise well — we often aim below 6.5%, because tighter control early in the disease can reduce long-term complications
• Older adults, people who are frail, or patients with limited life expectancy — a more relaxed target (often 7.5% or higher) makes sense, because aiming too low raises the risk of dangerous low sugars without meaningful long-term benefit
• Patients with multiple comorbidities or hypo unawareness — again, a less aggressive target

Your target is a conversation, not a verdict. If it’s been more than a year or two since we talked about yours, please raise it at your next visit.

Who is at risk?

Anyone can develop Type 2 diabetes, but the risk is higher if you:

• Have a first-degree relative (parent, sibling, child) with diabetes
• Are overweight or obese, particularly around the waist
• Are of Asian ethnicity — Chinese, Malay, and Indian populations in Singapore all have a higher risk of Type 2 diabetes at lower body weights than Western populations. This means a BMI of 23 kg/m² is roughly equivalent in risk to a BMI of 25 in Western data.
• Are over 40
• Have a history of gestational diabetes or gave birth to a baby over 4 kg
• Have pre-diabetes, high blood pressure, or high cholesterol
• Have polycystic ovary syndrome (PCOS)
• Are physically inactive most days of the week
• Have a history of cardiovascular disease

Not everyone at risk will develop diabetes — but if several of these apply to you, regular screening (every one to three years, depending on your risk) is worthwhile.

Signs you might be noticing — symptoms of poorly-controlled diabetes

One of the most common things we hear is “but I feel fine.” Diabetes can be silent for years, and early Type 2 often is. When symptoms do appear, they can be easy to dismiss as something else — “just getting older”, “work stress”, or the weather.

Symptoms that may come from poorly-controlled blood sugar include:

• Feeling unusually tired, even after a good night’s sleep
• Needing to pass urine more often, especially at night
• Feeling much thirstier than usual, or a dry mouth that doesn’t go away
• Unexplained weight loss, even while eating well (especially concerning — this often means insulin is dropping and cells can’t take up glucose)
• Blurred vision that comes and goes
• Slow-healing cuts and bruises on skin — particularly on the feet
• Recurrent thrush or fungal infections (groin, feet, under the breasts)
• Frequent urinary tract infections
• Tingling, numbness, or burning in the feet or hands (early nerve damage)
• Feeling “not quite right” without being able to say why — sometimes a vague unwellness is the first clue

If one or two of these have crept in, please don’t wait for your next scheduled review. Let us know at an earlier appointment — often, a HbA1c and a urine dipstick at the visit can tell us quickly whether your diabetes needs a treatment adjustment.

Why long-term control matters — what diabetes affects

High blood sugar over years damages two things: small blood vessels (microvascular) and large blood vessels (macrovascular). Most of the complications you may have heard of come from one of these.

• Eyes — damage to tiny blood vessels in the retina (diabetic retinopathy). Annual retinal photography catches this early, when treatment is most effective. This is covered in detail in Preventive care for diabetes.
• Kidneys — diabetes is the leading cause of chronic kidney disease and kidney failure in Singapore. We screen with a urine test (UACR) and a blood test (eGFR) at least once a year.
• Nerves — nerve damage (diabetic neuropathy) typically starts in the feet: numbness, tingling, burning pain. Numb feet mean small injuries can be missed until they’re serious — which is why annual foot checks are part of routine care.
• Heart and blood vessels — people with diabetes have roughly double the risk of heart attack, stroke, and peripheral vascular disease. Managing blood pressure, cholesterol, and lifestyle is as important as managing the glucose itself.
• Infections and slow healing — higher glucose impairs the immune response and slows wound healing. Minor infections can escalate more quickly than they would in someone without diabetes.
• Mood — depression is about twice as common in people with diabetes. It often goes unrecognised. We screen for it in routine reviews using short questionnaires (PHQ-2, PHQ-9), because treating mood properly usually helps blood sugar as well, and vice versa.
• Dental health — gum disease (periodontitis) is more common and more severe in diabetes. Regular dental check-ups matter.

The good news: most of these complications can be delayed or avoided with good long-term control, regular monitoring, and early treatment when problems are picked up. That’s exactly what the rest of this series is about.

The Singapore context — programmes that support you

You are not navigating this alone. Several national programmes reduce the financial and practical burden of long-term diabetes care:

• Healthier SG — if you’re aged 40 or over and a Singapore Citizen or PR, you can enrol with us as your Healthier SG family doctor. Patients enrolled in Healthier SG can purchase chronic medications at prices similar to polyclinic prices under the HSG Chronic Tier (in effect since February 2024). See our Healthier SG guide.
• Community Health Assist Scheme (CHAS) — means-tested subsidies for consultations and selected medications at participating GP clinics. Most Singapore Citizens qualify for at least the CHAS Green tier (subsidies for chronic conditions); CHAS Orange and Blue cardholders, and Pioneer Generation (PG) / Merdeka Generation (MG) cardholders, receive higher subsidies. More at chas.sg.
• MediSave — usable for chronic disease consultations, selected medications, and certain screenings. Current withdrawal limit: $500 per year per account for chronic conditions, rising to $700 (basic) / $1,000 (complex) in January 2027. Family members’ MediSave accounts can be used as well.
• Nurse-led counselling — available at your enrolled Healthier SG GP clinic or through your Primary Care Network, for lifestyle change, diet, smoking cessation, and self-management. More on this in Preventive care for diabetes.

We’ll help you navigate all of these at your consultations — just ask if something isn’t clear.

What’s next

Daily choices around food, movement, sleep, and stress are the foundation of diabetes care — far more important, most of the time, than any medication. That’s what we cover in part 2 of this series:

→ Diet and lifestyle for diabetes and pre-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). Managing pre-diabetes — a growing health concern. Updated July 2021. ace-hta.gov.sg
• Agency for Care Effectiveness (ACE). Oral glucose-lowering agents in type 2 diabetes mellitus — an update. Updated August 2017.
• Agency for Care Effectiveness (ACE). Initiating basal insulin in type 2 diabetes mellitus. Updated November 2024.
• Ministry of Health Singapore. War on Diabetes national programme. moh.gov.sg
• American Diabetes Association. Standards of Care in Diabetes — 2026. diabetesjournals.org

This information is for general education only and is not a substitute for medical advice. Diabetes care must be individualised — please speak with our team about what’s right for you. v1.0 · April 2026 · Review due April 2028.