What is diabetes and pre-diabetes?

In brief

• Diabetes means blood sugar (glucose) stays too high; Type 2 makes up about 90% of diabetes in Singapore.
• Without changes, at least 35% of people with pre-diabetes progress to Type 2 diabetes within eight years.
• Lifestyle changes are the foundation of care and can cut that risk by roughly a third.
• Diagnosis uses fasting glucose, an oral glucose tolerance test or HbA1c; a common HbA1c target is below 7.0%.
• Diabetes is often silent, so watch for thirst, passing more urine, tiredness, blurred vision and unexplained weight loss.
• Good long-term control and regular checks can delay or avoid most complications.

We diagnose and manage diabetes and pre-diabetes at our Punggol clinic. See our chronic disease care.

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

What is diabetes?

Diabetes is a long-term condition in which blood sugar (glucose) is too high. Glucose is your body’s main source of energy. It comes mostly from carbohydrates such as rice, noodles, bread, potatoes, sugar and fruit.

After a meal, your pancreas releases a hormone called insulin. Insulin acts as a key that lets glucose into your cells. When insulin doesn’t work well, glucose stays in the blood. Over time, high glucose damages blood vessels and nerves.

Two things can go wrong:

• The body responds poorly to insulin (insulin resistance). The key works, but the lock is rusty, so more insulin is needed for the same job.
• The body doesn’t make enough insulin. The insulin-producing cells in the pancreas (beta cells) slow down or stop.

The types of diabetes reflect different mixes of these two problems.

The main types of diabetes

Type 2 diabetes

By far the most common type, making up about 90% of diabetes in Singapore. It develops over years. Insulin resistance comes first, and the pancreas slowly struggles to keep up. It often comes with higher blood pressure, higher cholesterol and extra weight around the waist.

Diet, activity and weight strongly influence Type 2, but genes play a significant part. Many people do everything right and still get it because of their family history. If that’s you, it’s not your fault.

This series focuses mainly on Type 2.

Type 1 diabetes

In Type 1 diabetes, the immune system destroys the insulin-producing cells, usually early in life. People with Type 1 need insulin from diagnosis onward. In Singapore, an endocrinologist usually follows Type 1, and primary-care clinics like ours support day-to-day care.

Gestational diabetes

Gestational diabetes (GDM) is diabetes found during pregnancy, usually in the second or third trimester. Pregnancy hormones naturally raise insulin resistance. GDM is common in Singapore: about 1 in 4 to 5 pregnant women develop it, a higher rate than in Western populations.

All women are screened at 24 to 28 weeks of pregnancy with a 3-point 75 g oral glucose tolerance test. Women at higher risk are also screened in the first trimester, to pick up diabetes that was already there. Higher risk includes a pre-pregnancy BMI ≥23 kg/m², previous GDM, PCOS, older maternal age or a strong family history of diabetes.

The obstetric team manages GDM during pregnancy, usually with lifestyle changes and sometimes insulin. Blood sugar often returns to normal after delivery, but the future risk is significant:

• Women who have had GDM are about 10 times more likely to develop Type 2 diabetes later in life.
• About 4 in 10 develop Type 2 diabetes or pre-diabetes within 4 to 6 years of delivery.

If you have had GDM, come in for a follow-up 75 g OGTT 6 to 12 weeks after delivery, then screen every year. Lifestyle changes before any future pregnancy lower the risk of GDM coming back or progressing to Type 2.

What is pre-diabetes?

Pre-diabetes is the stage before Type 2 diabetes. Your blood sugar is higher than normal, but not high enough to be called diabetes. It is a warning sign, and an opportunity.

Pre-diabetes is more common than diabetes itself. About 14% of adults in Singapore have it, and many don’t know. Without changes, at least 35% will progress to Type 2 diabetes within eight years. Good lifestyle changes, and occasionally medication, can cut that risk by roughly a third.

We take pre-diabetes as seriously as early diabetes. Think of it as a fork in the road, not bad news.

Your numbers — what they mean

Three blood tests are used most in clinic.

Fasting plasma glucose (FPG)

Taken after 8 hours without food.

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

You drink a standard glucose drink, and blood is taken 2 hours later. It can 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. It needs no fasting or special drink.

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

HbA1c is also the main test for tracking long-term control once you have diabetes. Pre-diabetes is still diagnosed with FPG or OGTT; an HbA1c of 6.1–6.9% prompts those tests.

When HbA1c may not be reliable

Some conditions make HbA1c falsely high or low, so we usually use FPG or OGTT instead:

• Thalassaemia or other haemoglobin variants (around 3% of people in Singapore carry a thalassaemia gene)
• Iron, vitamin B12 or folate deficiency
• Recent blood transfusion or significant blood loss
• Chronic kidney or liver disease
• Pregnancy, when HbA1c tends to read low because red blood cells turn over faster, so OGTT is used instead

When your numbers don’t agree

Sometimes FPG and HbA1c disagree, for example a normal FPG with an HbA1c of 6.5%. We usually repeat the test to rule out lab variation or a short-term change. We often add an OGTT to see how your body handles a sugar load, which makes the diagnosis more certain.

Rarer forms of diabetes

Most adults with high blood sugar have Type 1 or Type 2 diabetes, but occasionally the cause is less common:

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

If the usual pattern doesn’t fit, we may arrange extra tests such as C-peptide, diabetes-related autoantibodies or, occasionally, genetic testing. Examples are 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. Treatment can differ significantly, so the right diagnosis matters.

Your personal HbA1c target

A common target is below 7.0%, but yours should fit you:

• Younger adults, newly diagnosed and otherwise well: we often aim below 6.5%, because tighter control early can reduce long-term complications.
• Older adults, people who are frail, or people with limited life expectancy: a more relaxed target (often 7.5% or higher) makes sense. Aiming too low raises the risk of dangerous low sugars without meaningful long-term benefit.
• Multiple other conditions, or hypo unawareness: again, a less aggressive target.

Your target is a conversation, not a verdict. If you haven’t discussed yours for a year or two, 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 or child) with diabetes
• Are overweight or obese, particularly around the waist
• Are of Asian ethnicity. Chinese, Malay and Indian people in Singapore develop Type 2 diabetes at lower body weights than Western populations. A BMI of 23 kg/m² carries roughly the same risk as a BMI of 25 in Western data.
• Are over 40
• Have had gestational diabetes, or a baby weighing over 4 kg
• Have pre-diabetes, high blood pressure or high cholesterol
• Have polycystic ovary syndrome (PCOS)
• Are physically inactive most days
• Have a history of cardiovascular disease

Not everyone at risk develops diabetes. If several of these apply, screening every one to three years, depending on your risk, is worthwhile.

Signs and symptoms of poorly controlled diabetes

We often hear “but I feel fine.” Early Type 2 diabetes is often silent for years. When symptoms appear, they are easy to put down to “just getting older”, work stress or the weather.

Poorly controlled blood sugar can cause:

• Unusual tiredness, even after a good night’s sleep
• Passing urine more often, especially at night
• Thirst or a dry mouth that doesn’t go away
• Unexplained weight loss, even while eating well. This is especially concerning: it often means insulin is falling and cells can’t take up glucose.
• Blurred vision that comes and goes
• Slow-healing cuts and bruises, 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 knowing why; vague unwellness is sometimes the first clue

If one or two of these have crept in, don’t wait for your next scheduled review; book an earlier visit. An HbA1c and a urine dipstick can quickly show whether your treatment needs adjusting.

Why long-term control matters — what diabetes affects

Years of high blood sugar damage small blood vessels (microvascular) and large blood vessels (macrovascular). Most complications come from one or the other.

• Eyes: damage to tiny blood vessels in the retina (diabetic retinopathy). Annual retinal photography catches it early, when treatment works best. See Preventive care for diabetes.
• Kidneys: diabetes is the leading cause of chronic kidney disease and kidney failure in Singapore. We screen at least once a year with a urine test (UACR) and a blood test (eGFR), and more often if results are abnormal.
• Nerves: nerve damage (diabetic neuropathy) usually starts in the feet, with numbness, tingling or burning pain. Numb feet can miss small injuries until they are serious, so annual foot checks are routine.
• 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 matters as much as managing glucose.
• Infections and slow healing: high glucose weakens the immune response and slows healing, so minor infections can escalate quickly.
• Mood: depression is about twice as common in people with diabetes and often goes unrecognised. We screen for it at routine reviews with short questionnaires (PHQ-2, PHQ-9). Treating mood usually helps blood sugar, and vice versa.
• Dental health: gum disease (periodontitis) is more common and more severe in diabetes, so regular dental check-ups matter.

Most of these complications can be delayed or avoided with good long-term control, regular monitoring and early treatment, which the rest of this series covers.

The Singapore context — programmes that support you

Diabetes affects roughly 1 in 10 Singaporeans, and the number is growing. The Ministry of Health launched the War on Diabetes national programme in 2016. Several national schemes reduce the cost and effort of long-term care:

• Healthier SG: Singapore Citizens and PRs aged 40 or over can enrol with us as their Healthier SG family doctor. Enrolled CHAS, Pioneer Generation and Merdeka Generation cardholders can buy selected chronic medications at prices comparable to polyclinic prices under the Healthier SG 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 CHAS Green, which subsidises chronic conditions. CHAS Orange and Blue, Pioneer Generation (PG) and Merdeka Generation (MG) cardholders receive higher subsidies. More at chas.sg.
• MediSave: usable for chronic disease consultations, selected medications and certain screenings and vaccinations. Under the MediSave500/700 scheme, the limit is $500 per patient per year for chronic conditions ($700 for complex chronic conditions). From 1 January 2027 it rises to $700 (basic) / $1,000 (complex), and the scheme is renamed the MediSave Chronic and Preventive Care scheme. You can also use immediate family members’ accounts.
• Nurse-led counselling: available at your Healthier SG clinic or through your Primary Care Network, for lifestyle change, diet, smoking cessation and self-management. See Preventive care for diabetes.

Ask us if anything here isn’t clear.

What’s next

Daily choices about food, movement, sleep and stress are the foundation of diabetes care, and usually matter far more than any medication. Part 2 covers them:

→ Diet and lifestyle for diabetes and pre-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). 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
• Ministry of Health Singapore. MOH Circular No. 08/2019 — Release of new Screening Test Review Committee guidelines (Annex C: HbA1c as an alternative initial screening test for diabetes mellitus). 6 March 2019.
• Ministry of Health Singapore. Healthier SG Chronic Tier subsidy framework to start from 1 February 2024. 25 January 2024. moh.gov.sg
• Ministry of Health Singapore. Keeping healthcare affordable (MediSave500/700 limits and renaming from 1 January 2027). 5 March 2026. moh.gov.sg
• Central Provident Fund Board. Using MediSave for outpatient treatments. cpf.gov.sg

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. v1.1 · October 2026 (v1.0 April 2026) · Review due April 2028.