Type 2 Diabetes: Causes, Complications and Treatment

Type 2 diabetes mellitus (T2DM) is the most common metabolic disorder worldwide, affecting approximately 537 million adults — 1 in 10 globally — and projected to reach 783 million by 2045. It is the leading cause of kidney failure, adult-onset blindness, and non-traumatic lower limb amputation, and a major driver of cardiovascular disease and stroke.

China has the largest absolute burden of diabetes of any country — an estimated 140 million adults with diabetes, and a further 350 million with prediabetes. The scale of this epidemic makes diabetes management one of the most urgent healthcare priorities in the region.

What Is Type 2 Diabetes?

Type 2 diabetes is characterised by chronic hyperglycaemia — persistently elevated blood glucose — resulting from two core defects:

1. Insulin resistance: target tissues (muscle, liver, fat) fail to respond normally to insulin, requiring the pancreas to produce more insulin to achieve the same glucose-lowering effect
2. Progressive beta-cell failure: the insulin-secreting beta cells of the pancreatic islets become exhausted and gradually fail, unable to compensate for the increased insulin demand

Unlike type 1 diabetes (an autoimmune condition causing complete beta-cell destruction), type 2 diabetes has partial insulin production — though this declines over years — and is strongly driven by lifestyle and genetic factors.

Causes and Risk Factors

Modifiable Risk Factors

Overweight and obesity — central (abdominal) obesity is the strongest modifiable risk factor. Visceral adipose tissue releases fatty acids and inflammatory adipokines that promote hepatic insulin resistance and impair beta-cell function. Each 1 kg/m² increase in BMI increases T2DM risk by approximately 9%.

Physical inactivity — skeletal muscle accounts for approximately 80% of postprandial glucose uptake; inactivity impairs glucose transport into muscle independently of weight.

Diet — high intake of refined carbohydrates, sugar-sweetened beverages, processed meats, and saturated fats increases risk; Mediterranean and DASH diets are protective.

Prediabetes — impaired fasting glucose (6.1–6.9 mmol/L) or impaired glucose tolerance (2-hour glucose 7.8–11.0 mmol/L after oral glucose load); 25–50% of individuals with prediabetes progress to T2DM within 5 years without intervention.

Gestational diabetes — diabetes during pregnancy substantially raises subsequent T2DM risk.

Non-Modifiable Risk Factors

• Age (risk rises sharply after 45)
• Family history (first-degree relative with T2DM: 3× increased risk)
• Ethnicity (South Asian, East Asian, Hispanic, Black African: earlier onset, higher risk at lower BMI)
• Polycystic ovary syndrome (PCOS)
• Prior gestational diabetes

Symptoms

Type 2 diabetes often develops insidiously — many patients are diagnosed incidentally on routine blood tests or at the time of a complication.

Classic hyperglycaemic symptoms (occur when glucose is high — typically >10–15 mmol/L):

• Polyuria — excessive urination (osmotic diuresis: glucose in urine draws water)
• Polydipsia — excessive thirst (responding to dehydration from polyuria)
• Polyphagia — increased hunger despite eating
• Unexplained weight loss (glucose lost in urine; cellular starvation despite high blood glucose)
• Fatigue — cells cannot utilise glucose effectively without insulin
• Blurred vision — osmotic changes in the lens with high glucose

Other common presentations:

• Recurrent infections (urinary tract, skin, thrush) — glucose-rich environment promotes bacterial and fungal growth
• Slow-healing wounds
• Peripheral tingling or numbness (early diabetic neuropathy)
• Erectile dysfunction

Diagnosis

Diabetes is diagnosed by any of:

Test	Diabetes Threshold	Prediabetes Range
Fasting plasma glucose	≥7.0 mmol/L	6.1–6.9 mmol/L
2-hour glucose (OGTT)	≥11.1 mmol/L	7.8–11.0 mmol/L
Random plasma glucose + symptoms	≥11.1 mmol/L	—
HbA1c	≥48 mmol/mol (6.5%)	42–47 mmol/mol (6.0–6.4%)

A single abnormal result in an asymptomatic patient requires confirmation with a repeat test on a different day. HbA1c reflects average blood glucose over the preceding 2–3 months and is the preferred monitoring tool.

Long-Term Complications

Chronic hyperglycaemia damages blood vessels and nerves throughout the body through several mechanisms — protein glycation, oxidative stress, inflammation, and polyol pathway activation.

Microvascular Complications (small vessel disease)

• Diabetic retinopathy — the most common cause of blindness in working-age adults; affects virtually all T1DM patients and 60–80% of T2DM patients after 20 years; annual eye screening is essential
• Diabetic nephropathy — progressive kidney damage; 20–40% of diabetic patients develop chronic kidney disease; leading cause of end-stage renal disease requiring dialysis
• Diabetic neuropathy — damage to peripheral nerves; affects 50% of patients with long-standing diabetes; causes peripheral sensory neuropathy (tingling, numbness, pain in feet and hands), autonomic neuropathy (erectile dysfunction, gastroparesis, orthostatic hypotension), and Charcot foot

Macrovascular Complications (large vessel disease)

• Cardiovascular disease — the leading cause of death in diabetic patients; 2–4× increased risk of myocardial infarction and stroke compared to non-diabetic individuals
• Peripheral arterial disease — reduced circulation to the limbs; contributes to diabetic foot ulcers and the risk of amputation

Diabetic Foot

Peripheral neuropathy (loss of protective sensation) combined with peripheral arterial disease (poor healing) creates the diabetic foot — susceptible to unrecognised trauma, ulceration, infection, and osteomyelitis. Annual foot inspection is mandatory.

Treatment

Lifestyle Intervention

Weight loss — the single most powerful intervention in T2DM. The DiRECT trial demonstrated that intensive dietary weight management achieving ≥10–15 kg weight loss produced remission of T2DM in 50–86% of patients (defined as HbA1c <48 mmol/mol off all medication) at 1 year. Even 5–10% weight loss significantly improves glycaemic control.

Physical activity — 150 minutes/week of moderate aerobic exercise (brisk walking) reduces HbA1c by 0.5–1%, independent of weight loss. Resistance training additionally improves insulin sensitivity.

Dietary modification — low-carbohydrate, Mediterranean, or very-low-calorie diets; reduction of refined carbohydrates and sugar-sweetened beverages; high vegetable and fibre intake.

Glucose-Lowering Medications

Treatment is typically stepped up over time as beta-cell function declines.

Metformin — first-line in most guidelines; reduces hepatic glucose output; lowers HbA1c by 1–2%; weight-neutral or modest weight loss; 60+ years of evidence; cheap; the backbone of T2DM pharmacotherapy.

GLP-1 receptor agonists (semaglutide — Ozempic/Wegovy; liraglutide — Victoza/Saxenda; dulaglutide — Trulicity; exenatide):

• Stimulate glucose-dependent insulin secretion, suppress glucagon, slow gastric emptying, reduce appetite
• HbA1c reduction 1–2%; significant weight loss (5–15% with semaglutide)
• Proven cardiovascular risk reduction (LEADER, SUSTAIN-6, REWIND trials)
• Available as weekly subcutaneous injection (semaglutide) or daily/weekly pens
• Now considered preferred second-line agents in patients with cardiovascular disease or obesity

SGLT-2 inhibitors (empagliflozin — Jardiance; dapagliflozin — Forxiga; canagliflozin — Invokana):

• Block glucose reabsorption in the kidneys, causing glycosuria (glucose lost in urine)
• HbA1c reduction 0.7–1%; weight loss 2–3 kg; blood pressure reduction
• Significant heart failure prevention and renoprotection (EMPA-REG, DECLARE, CREDENCE trials)
• Preferred in patients with heart failure or chronic kidney disease

DPP-4 inhibitors (sitagliptin — Januvia; saxagliptin; vildagliptin):

• Prolong endogenous GLP-1 action; glucose-dependent; weight-neutral
• HbA1c reduction 0.5–1%; well tolerated; convenient oral tablets

Sulfonylureas (glibenclamide, gliclazide, glipizide):

• Stimulate insulin secretion regardless of glucose level; risk of hypoglycaemia and weight gain
• Inexpensive; still widely used but falling out of favour with newer agents

Thiazolidinediones (pioglitazone):

• Improve insulin sensitivity; durable effect; weight gain and fluid retention limit use

Insulin therapy:

• Required when oral/injectable agents fail to achieve HbA1c targets
• Basal insulin (glargine, detemir, degludec) — once-daily long-acting injection; controls fasting glucose
• Premixed insulin — twice-daily injections; convenient but less flexible
• Intensive basal-bolus regimens — multiple daily injections mimicking physiological insulin secretion; required for marked hyperglycaemia

Target HbA1c

Patient Group	HbA1c Target
Most adults with T2DM	<53 mmol/mol (7%)
Young, fit, no complications	<48 mmol/mol (6.5%)
Elderly, frail, hypoglycaemia risk	<58–64 mmol/mol (7.5–8%)
Established cardiovascular disease	<53 mmol/mol; use GLP-1 or SGLT-2
Chronic kidney disease	<53 mmol/mol; dapagliflozin preferred

Cardiovascular and Renal Risk Reduction

Glycaemic control alone is insufficient — the majority of diabetes-related mortality is cardiovascular:

• Statin therapy — all diabetic patients with cardiovascular risk; target LDL <2.6 mmol/L (or <1.8 mmol/L with established CVD)
• Antihypertensive therapy — target BP <130/80 mmol/L; ACE inhibitor or ARB preferred (renoprotective)
• Aspirin — low-dose for secondary prevention in those with established CVD
• Smoking cessation — doubles cardiovascular risk in diabetics

Bariatric / Metabolic Surgery

For patients with T2DM and BMI ≥35 kg/m² (or ≥30 in Asian populations), bariatric surgery (gastric bypass, sleeve gastrectomy) produces durable diabetes remission in 50–70% of patients at 5 years — far superior to any medication. Mechanisms include weight loss, gut hormone changes, and changes in bile acid signalling.

Diabetes Care in China

China's diabetes and endocrinology centres offer:

• Comprehensive diabetes work-up: HbA1c, fasting and postprandial glucose, C-peptide (insulin reserve), insulin resistance assessment (HOMA-IR), full lipid panel, renal function, urine albumin-creatinine ratio, and complete complication screening
• Multidisciplinary diabetes team: endocrinologist, diabetes educator, dietitian, podiatrist, ophthalmologist, and nephrologist in an integrated care pathway
• CGM (continuous glucose monitoring): Freestyle Libre and Dexcom G6/G7 used routinely to guide medication titration and pattern recognition
• Metabolic surgery programme: high-volume bariatric and metabolic surgery for T2DM with obesity — outcomes comparable to international centres
• Access to modern diabetes medications: GLP-1 agonists (semaglutide, liraglutide), SGLT-2 inhibitors, and all basal insulins available; Chinese domestic biosimilar insulins available
• Cost: care in China is generally less expensive than UK private treatment, but the hospital prices each case individually — ask us for the written quote before you commit.
• Full English care navigation throughout assessment, treatment optimisation, and follow-up

Contact a ChinaMedicalTour care navigator to arrange a diabetes assessment, medication review, or metabolic surgery consultation.

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Medical content based on MSD Manuals and international diabetes guidelines (ADA Standards of Care 2025). Evidence reviewed 2025.

Frequently Asked Questions

What comprehensive diagnostic evaluations are available for endocrine and metabolic disorders in China?

Tertiary endocrinology departments provide continuous glucose monitoring, comprehensive metabolic panels, hormone assays, thyroid fine-needle aspiration biopsy, and DEXA bone densitometry.

How do Chinese medical teams approach metabolic and chronic endocrine management?

Care combines clinical endocrinologist consultations, individualized pharmacological regimens, nutritional guidance, and multidisciplinary screening for cardiovascular and microvascular complications.

Can international visitors combine endocrine consultations with a general medical checkup?

Yes. Specialized endocrine evaluations can be coordinated alongside comprehensive executive checkups or specialist referrals to optimize traveling schedules.