A Hidden Epidemic
China is home to the largest diabetic population in the world. According to data from the International Diabetes Federation, approximately 140 million adults in China were living with diabetes as of 2021 — roughly 1 in 9 adults. More striking still is the estimated number of people with prediabetes: over 400 million, representing nearly half of the adult population.
The vast majority of people with prediabetes — and a significant proportion of those with early type 2 diabetes — are unaware of their condition. They feel well. Their energy levels seem normal. They have no obvious symptoms. Yet inside their bodies, a slow metabolic deterioration is underway that, left unaddressed, will significantly increase their risk of heart disease, stroke, kidney failure, blindness, nerve damage, and premature death.
Blood sugar screening is the tool that makes this invisible process visible — early enough to intervene effectively.
How Type 2 Diabetes Develops
Type 2 diabetes does not appear overnight. It develops over a continuum that typically spans years or even decades, passing through several identifiable stages:
Insulin resistance: The earliest stage, in which the body's cells become less responsive to insulin — the hormone that allows glucose to enter cells for energy. The pancreas compensates by producing more insulin, keeping blood sugar levels normal. At this stage, standard blood glucose tests may appear normal, but fasting insulin levels are elevated.
Prediabetes: As insulin resistance worsens, the pancreas can no longer fully compensate, and blood glucose levels begin to rise above normal — but not yet into the diabetic range. This stage is defined by a fasting blood glucose of 5.6–6.9 mmol/L (100–2 mg/dL) or an HbA1c of 5.7–6.4%. Prediabetes is largely asymptomatic and is estimated to affect 35–40% of adults in China.
Type 2 diabetes: Defined by a fasting blood glucose of 7.0 mmol/L or above, an HbA1c of 6.5% or above, or a 2-hour glucose of 11.1 mmol/L or above on an oral glucose tolerance test (OGTT). At this stage, complications may already be developing in blood vessels, nerves, and organs — even before the diagnosis is made.
The critical insight is that prediabetes is not a minor or benign condition. It is a window of opportunity: a stage at which the trajectory toward diabetes can be reversed through lifestyle intervention, without medication, in the majority of cases.
The Three Key Blood Sugar Tests — and What They Each Measure
Understanding the differences between the main blood sugar tests helps clarify what each one tells you — and why more than one may be needed for a complete picture.
Fasting blood glucose (FBG): Measures blood sugar after at least 8 hours without food. It is the most widely used first-line screening test — simple, inexpensive, and standardized. However, it captures only a single point in time and can miss individuals whose blood sugar is normal in the fasting state but rises excessively after meals (postprandial hyperglycemia).
HbA1c (glycated hemoglobin): Measures the percentage of hemoglobin molecules that have glucose attached to them — a reflection of average blood sugar levels over the preceding 2–3 months. HbA1c does not require fasting, is less affected by day-to-day fluctuations, and provides a more stable long-term picture than a single fasting glucose reading. It is now widely used for both screening and monitoring of diabetes management.
Oral glucose tolerance test (OGTT): The patient drinks a standardized glucose solution (75g), and blood sugar is measured at baseline and 2 hours later. The OGTT is the most sensitive test for detecting impaired glucose tolerance and early diabetes, particularly in individuals whose fasting glucose and HbA1c appear borderline normal. It is more cumbersome than the other tests but provides the most complete picture of glucose metabolism.
For a comprehensive metabolic assessment, particularly in adults over 40 with risk factors, a combination of fasting glucose, HbA1c, and fasting insulin (to assess insulin resistance) is more informative than any single test alone.
Metabolic Syndrome: When Risk Factors Cluster
Metabolic syndrome is not a single disease but a cluster of interrelated metabolic abnormalities that together dramatically increase the risk of type 2 diabetes and cardiovascular disease. It is diagnosed when three or more of the following criteria are present:
- Abdominal obesity: Waist circumference above 90 cm in Asian men or 80 cm in Asian women (thresholds are lower for Asian populations than for Western populations, reflecting differences in body composition and fat distribution)
- Elevated triglycerides: 1.7 mmol/L (150 mg/dL) or above
- Low HDL cholesterol: Below 1.0 mmol/L (40 mg/dL) in men or 1.3 mmol/L (50 mg/dL) in women
- Elevated blood pressure: 130/85 mmHg or above, or on antihypertensive medication
- Elevated fasting blood glucose: 5.6 mmol/L (100 mg/dL) or above, or on glucose-lowering medication
Metabolic syndrome affects an estimated 25–30% of adults in China — and its prevalence rises sharply with age. An individual with metabolic syndrome has approximately a five-fold increased risk of developing type 2 diabetes and a two- to three-fold increased risk of cardiovascular disease compared to someone without the syndrome.
The underlying driver of metabolic syndrome is insulin resistance, compounded by visceral (abdominal) fat accumulation, chronic low-grade inflammation, and hormonal dysregulation. Importantly, metabolic syndrome can be present — and causing damage — in individuals who appear outwardly healthy and have a normal BMI, particularly in Asian populations where visceral fat accumulation can occur at lower body weights.
Why Asian Populations Face Particular Risk
Type 2 diabetes and metabolic syndrome disproportionately affect East Asian populations at lower BMI thresholds than Western populations. A Chinese adult with a BMI of 24 — classified as "normal" by Western standards — may carry a level of visceral fat and insulin resistance equivalent to a Western adult with a BMI of 28–30.
This means that standard BMI-based risk thresholds underestimate metabolic risk in Chinese adults. The World Health Organization and the International Diabetes Federation have recommended lower waist circumference and BMI thresholds for Asian populations, and Chinese national guidelines reflect this. A waist circumference above 90 cm in Chinese men or 85 cm in Chinese women is considered a risk factor for metabolic syndrome, regardless of overall body weight.
The Consequences of Uncontrolled Blood Sugar
The complications of poorly controlled diabetes are well-documented and severe:
- Cardiovascular disease: Adults with diabetes have a two- to four-fold higher risk of heart attack and stroke than non-diabetic adults. Cardiovascular disease is the leading cause of death in people with type 2 diabetes.
- Diabetic nephropathy: Kidney damage caused by chronic hyperglycemia; the leading cause of end-stage kidney disease requiring dialysis in China.
- Diabetic retinopathy: Damage to the blood vessels of the retina; the leading cause of new blindness in working-age adults.
- Diabetic neuropathy: Nerve damage causing pain, numbness, and loss of sensation, particularly in the feet; a major contributor to lower limb amputations.
- Increased cancer risk: Type 2 diabetes is associated with elevated risk of liver, pancreatic, colorectal, and endometrial cancers.
All of these complications are substantially preventable — or their progression significantly delayed — through early detection and effective management of blood sugar, blood pressure, and lipids.
Prediabetes Is Reversible: The Evidence
The landmark US Diabetes Prevention Program (DPP) trial demonstrated that intensive lifestyle intervention — achieving a 7% reduction in body weight and 150 minutes of moderate physical activity per week — reduced the progression from prediabetes to type 2 diabetes by 58% over three years. This was more effective than metformin (which reduced progression by 31%).
Subsequent studies in Chinese populations have confirmed similar results. The Da Qing Diabetes Prevention Study, conducted in China over 23 years, showed that lifestyle intervention in people with impaired glucose tolerance reduced diabetes incidence by 43% and cardiovascular mortality by 41% compared to a control group.
These findings carry a clear message: identifying prediabetes through screening, and acting on it through lifestyle change, is one of the highest-impact interventions available in preventive medicine.
What a Comprehensive Metabolic Screening Should Include
For adults over 40, a thorough metabolic assessment should cover:
- Fasting blood glucose and HbA1c
- Fasting insulin (to calculate HOMA-IR, a measure of insulin resistance)
- Full lipid profile (total cholesterol, LDL, HDL, triglycerides, non-HDL cholesterol)
- Waist circumference measurement
- Blood pressure
- Liver function tests and abdominal ultrasound (to assess for non-alcoholic fatty liver disease, which is closely linked to insulin resistance)
- Urine microalbumin (early marker of kidney involvement)
- Thyroid function (TSH) — thyroid disorders can affect glucose metabolism and are common in middle-aged adults
A Note for International Patients in Shanghai
Comprehensive metabolic screening — including all of the tests listed above — is available at Shanghai's leading hospitals and can typically be completed within a single morning. For international patients who want a thorough metabolic health assessment with results explained in English, China Medical Concierge Shanghai (CMCS) can coordinate the full process and connect you with an endocrinologist or internist if follow-up is needed.
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