Diabetes mellitus Medical Services in China

Diabetes mellitus is a chronic, progressive metabolic disorder characterized by persistent hyperglycemia resulting from defects in insulin secretion, insulin action, or both. It is broadly classified into type 1 diabetes (T1D), an autoimmune condition causing near-total beta-cell destruction and absolute insulin deficiency; type 2 diabetes (T2D), the most prevalent form, driven by insulin resistance and relative insulin deficiency; gestational diabetes mellitus (GDM), which develops during pregnancy; and other specific types including monogenic diabetes and secondary forms due to pancreatic disease, endocrinopathies, or medications. Pathogenesis involves complex interactions among genetic susceptibility, epigenetic modulation, environmental triggers (e.g., sedentary lifestyle, ultra-processed diets, chronic stress), and immune dysregulation—particularly in T1D where autoreactive T-cells destroy insulin-producing islet beta cells. In T2D, adipose tissue inflammation, mitochondrial dysfunction in skeletal muscle and liver, and impaired incretin signaling contribute to systemic insulin resistance and progressive beta-cell failure. Globally, diabetes affects over 537 million adults (2023 IDF Atlas), with prevalence projected to rise to 643 million by 2030. China bears the world’s largest diabetes burden—approximately 141 million adults live with the disease, and another 388 million have prediabetes. Key modifiable risk factors include obesity (especially central adiposity), physical inactivity, unhealthy diet high in refined carbohydrates and saturated fats, smoking, and sleep deprivation; non-modifiable risks include age >45 years, family history, history of GDM, polycystic ovary syndrome (PCOS), and certain ethnic backgrounds (e.g., Han Chinese exhibit heightened susceptibility to beta-cell dysfunction at lower BMI thresholds). Uncontrolled diabetes significantly impairs quality of life: patients report higher rates of fatigue, depression, anxiety, sexual dysfunction, and cognitive decline. Microvascular complications—including retinopathy (leading cause of adult-onset blindness), nephropathy (a major cause of end-stage renal disease), and neuropathy (causing pain, foot ulcers, and amputations)—and macrovascular complications such as coronary artery disease, stroke, and peripheral arterial disease substantially increase morbidity and mortality. Early diagnosis, individualized glycemic targets, comprehensive cardiovascular risk management (blood pressure, lipids, antithrombotic therapy), structured diabetes self-management education and support (DSMES), and psychosocial care are essential to preserve function, prevent complications, and sustain long-term well-being.

Diabetes mellitus is a heterogeneous group of chronic metabolic disorders characterized by persistent hyperglycemia resulting from defects in insulin secretion, insulin action, or both. The two principal forms—type 1 and type 2 diabetes—share the common endpoint of dysregulated glucose homeostasis but differ fundamentally in etiology, pathophysiology, and natural history. Type 1 diabetes (T1D) is an autoimmune-mediated disease wherein autoreactive T lymphocytes selectively destroy pancreatic beta cells in genetically susceptible individuals. This process leads to absolute insulin deficiency and lifelong dependence on exogenous insulin. Key triggers include viral infections (e.g., enteroviruses such as coxsackievirus B, rotavirus, and mumps virus), which may initiate molecular mimicry or bystander activation of autoreactive immune responses. Other potential environmental triggers include early dietary exposures (e.g., timing of gluten or cow’s milk introduction in infancy), vitamin D deficiency, and gut microbiome dysbiosis, all of which may modulate immune tolerance during critical developmental windows. Genetic susceptibility is strongly implicated: over 60 loci have been associated with T1D risk, with the HLA region (particularly HLA-DR3-DQ2 and HLA-DR4-DQ8 haplotypes) accounting for ~50% of familial clustering. Non-HLA genes—including INS (insulin gene promoter polymorphisms), PTPN22, CTLA4, and IL2RA—further influence immune regulation and beta-cell vulnerability.

Type 2 diabetes (T2D) arises from progressive insulin resistance in peripheral tissues (skeletal muscle, liver, adipose) coupled with relative insulin secretory failure due to beta-cell dysfunction and eventual loss. Unlike T1D, it is not autoimmune-driven but rather results from complex interactions between genetic predisposition and modifiable lifestyle factors. Central obesity—especially visceral adiposity—is a primary driver, promoting chronic low-grade inflammation, elevated free fatty acids, and adipokine dysregulation (e.g., reduced adiponectin, increased leptin resistance and resistin), all contributing to impaired insulin signaling via IRS-1/PI3K/AKT pathway inhibition. Beta-cell failure evolves over decades; glucotoxicity, lipotoxicity, endoplasmic reticulum stress, oxidative stress, and amyloid deposition (islet amyloid polypeptide) accelerate functional decline. Established risk factors include advancing age (>45 years), physical inactivity, sedentary behavior, and unhealthy dietary patterns high in refined carbohydrates, saturated fats, and sugar-sweetened beverages. Ethnicity confers differential risk: individuals of South Asian, East Asian, Hispanic, African American, Native American, and Pacific Islander descent exhibit higher prevalence at lower BMI thresholds, suggesting distinct body composition and metabolic phenotypes.

Genetic architecture of T2D is polygenic; genome-wide association studies have identified >250 susceptibility loci, many influencing beta-cell development (TCF7L2, KCNJ11, SLC30A8), insulin processing (PCSK1), insulin signaling (IRS1), and adipocyte biology (FTO, PPARG). Heritability estimates range from 30–70%, with first-degree relatives having 3–4-fold increased risk. Epigenetic modifications—DNA methylation, histone acetylation, and non-coding RNA expression—mediate gene–environment interactions, particularly in response to prenatal undernutrition (Barker hypothesis), gestational diabetes exposure, or postnatal overfeeding. Environmental contributors extend beyond diet and activity: chronic sleep deprivation, circadian misalignment, environmental pollutants (e.g., persistent organic pollutants, bisphenol A), and certain medications (e.g., glucocorticoids, atypical antipsychotics, thiazide diuretics) can impair glucose metabolism. Psychosocial stressors—including depression, anxiety, and socioeconomic disadvantage—correlate with elevated cortisol, sympathetic overactivity, and health-behavioral barriers that compound biological risk. Gestational diabetes mellitus (GDM) represents both a consequence and predictor of future T2D, reflecting underlying beta-cell insufficiency unmasked by pregnancy-induced insulin resistance; women with prior GDM face a 7-fold increased lifetime risk. Finally, monogenic forms (e.g., MODY, neonatal diabetes) account for <5% of cases but are clinically important due to implications for treatment selection and family screening. In summary, diabetes mellitus emerges from dynamic interplay among inherited susceptibility, developmental programming, immune dysregulation (in T1D), metabolic overload, and cumulative environmental exposures—underscoring the necessity for personalized, life-course–oriented prevention and management strategies.

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia resulting from defects in insulin secretion, insulin action, or both. It is classified primarily into type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), gestational diabetes mellitus (GDM), and other specific types (e.g., monogenic diabetes, drug-induced, pancreatic disease–related). Early recognition of symptoms is critical for timely diagnosis and prevention of long-term complications.

Early symptoms of diabetes are often subtle and nonspecific, particularly in T2DM, which may remain asymptomatic for years. Common early manifestations include mild fatigue, intermittent blurred vision due to transient osmotic lens changes, increased susceptibility to recurrent skin or mucosal infections (e.g., candidal vaginitis, balanitis, folliculitis), and impaired wound healing. Patients may report subjective cognitive slowing or 'brain fog,' especially postprandially, reflecting glucose dysregulation affecting cerebral metabolism. Mild polyuria and nocturia may be initially attributed to benign causes such as aging or caffeine intake. In prediabetes—defined by fasting plasma glucose 100–125 mg/dL, HbA1c 5.7–6.4%, or 2-hour oral glucose tolerance test (OGTT) values of 140–199 mg/dL—symptoms are typically absent, though some individuals exhibit subtle signs like acanthosis nigricans (velvety, hyperpigmented skin patches in intertriginous areas), which correlates with insulin resistance.

Typical symptoms—often termed the 'classic triad'—emerge when fasting glucose exceeds ~180–200 mg/dL and renal glucose threshold is surpassed. These include polyuria (excessive urine output >2.5 L/day), polydipsia (intense, unquenchable thirst), and polyphagia (excessive hunger despite caloric sufficiency). Polyuria results from osmotic diuresis induced by glucosuria; this leads to intravascular volume depletion, triggering hypothalamic thirst centers and consequent polydipsia. Polyphagia arises from cellular starvation: despite hyperglycemia, insulin deficiency or resistance impairs glucose uptake into skeletal muscle and adipose tissue, prompting counterregulatory hormone release (e.g., glucagon, cortisol, catecholamines) and increased lipolysis and proteolysis. Unintentional weight loss—particularly prominent in T1DM and ketosis-prone T2DM—is another hallmark, reflecting catabolism of fat and lean mass. Other typical features include generalized weakness, irritability, and decreased exercise tolerance.

Accompanying symptoms reflect multisystem involvement and may precede or co-occur with classic manifestations. Neuropathic symptoms include distal symmetric sensorimotor neuropathy (numbness, tingling, burning, or lancinating pain in feet/hands), autonomic dysfunction (orthostatic hypotension, gastroparesis with early satiety and nausea, neurogenic bladder, erectile dysfunction), and acute painful neuropathies (e.g., diabetic radiculoplexus neuropathy). Dermatologic signs include necrobiosis lipoidica diabeticorum (shiny, atrophic, yellow-brown plaques on shins), diabetic dermopathy (light brown, scaly, oval patches on pretibial skin), and eruptive xanthomas (yellow papules on buttocks, elbows, knees in severe hypertriglyceridemia). Ophthalmologic clues include fluctuating refractive error and delayed pupillary light reflex. Genitourinary symptoms include recurrent urinary tract infections (UTIs), pyelonephritis, and fungal balanitis or vulvovaginitis. Psychiatric comorbidities—especially depression and anxiety—are significantly more prevalent in persons with DM and may manifest as anhedonia, sleep disturbance, or reduced self-care motivation.

Complications arise from chronic hyperglycemia–induced microvascular and macrovascular damage, oxidative stress, and advanced glycation end-product accumulation. Microvascular complications include diabetic retinopathy (progressing from nonproliferative to proliferative stages, potentially causing blindness), diabetic nephropathy (manifested by microalbuminuria progressing to overt proteinuria, declining eGFR, and end-stage kidney disease), and diabetic peripheral neuropathy (increasing risk of foot ulceration and amputation). Macrovascular complications encompass accelerated atherosclerosis leading to coronary artery disease (angina, myocardial infarction), cerebrovascular disease (transient ischemic attack, ischemic stroke), and peripheral artery disease (claudication, critical limb ischemia). Other systemic complications include diabetic ketoacidosis (DKA)—a life-threatening emergency in T1DM and some T2DM patients featuring hyperglycemia (>250 mg/dL), ketonemia/ketonuria, metabolic acidosis (pH <7.3, serum bicarbonate <18 mEq/L), and dehydration—and hyperosmolar hyperglycemic state (HHS), more common in elderly T2DM patients, marked by extreme hyperglycemia (>600 mg/dL), profound dehydration, and hyperosmolality (>320 mOsm/kg) without significant ketosis.

Diagnosis relies on standardized biochemical criteria established by the American Diabetes Association (ADA) and World Health Organization (WHO). Fasting plasma glucose ≥126 mg/dL (7.0 mmol/L) after ≥8 hours fasting, HbA1c ≥6.5% (48 mmol/mol), random plasma glucose ≥200 mg/dL (11.1 mmol/L) in the presence of classic symptoms, or 2-hour plasma glucose ≥200 mg/dL during a 75-g OGTT confirm diabetes. Repeat testing is required for asymptomatic individuals unless unequivocal hyperglycemia is present. Additional diagnostic tools include C-peptide (to assess endogenous insulin production), autoantibodies (GAD65, IA-2, ZnT8, IAA) for T1DM differentiation, and continuous glucose monitoring (CGM) metrics (e.g., time-in-range, glucose variability) for functional assessment. Urine ketones and arterial blood gas analysis are essential in suspected DKA/HHS.

Differential diagnosis must exclude conditions mimicking diabetes or causing secondary hyperglycemia. These include stress-induced hyperglycemia (e.g., acute illness, trauma, surgery), steroid-induced diabetes (from glucocorticoid therapy), Cushing syndrome (hypercortisolism with central obesity, striae, hypertension), acromegaly (GH excess causing insulin resistance), pheochromocytoma (episodic catecholamine surges), and pancreatic diseases (chronic pancreatitis, cystic fibrosis–related diabetes, pancreatic cancer). Drug-induced hyperglycemia may result from thiazides, beta-blockers (nonselective), atypical antipsychotics (e.g., olanzapine), and protease inhibitors. Monogenic forms (e.g., MODY subtypes) should be considered in young, non-obese, non-autoimmune patients with strong family history and preserved C-peptide. Gestational diabetes requires distinction from preexisting T2DM via postpartum 75-g OGTT at 6–12 weeks. Finally, renal glycosuria (e.g., SGLT2 mutations) presents with glucosuria without hyperglycemia and normal glucose tolerance—differentiated by normoglycemic urine dipstick positivity and absence of metabolic abnormalities.

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Effective management requires a comprehensive, individualized, and multidisciplinary approach coordinated primarily within the Department of Endocrinology. Treatment strategies are stratified according to diabetes type (Type 1, Type 2, gestational, or other specific forms), disease duration, comorbidities, complications, and patient-specific factors including age, lifestyle, socioeconomic status, and treatment preferences.

Conservative (non-pharmacologic) treatment forms the cornerstone of diabetes care—particularly for Type 2 diabetes—and remains essential across all subtypes. Medical nutrition therapy (MNT) is evidence-based and personalized, emphasizing caloric balance, low glycemic index carbohydrates, high-fiber whole grains, lean proteins, and unsaturated fats. Dietary patterns such as the Mediterranean diet and plant-predominant approaches have demonstrated efficacy in improving glycemic control and cardiovascular risk profiles. Structured physical activity—comprising at least 150 minutes per week of moderate-intensity aerobic exercise (e.g., brisk walking, cycling) combined with resistance training twice weekly—is strongly recommended to enhance insulin sensitivity, reduce visceral adiposity, and improve lipid metabolism. Behavioral interventions, including cognitive-behavioral therapy, motivational interviewing, and digital health coaching, support long-term adherence to lifestyle modifications. Smoking cessation and alcohol moderation (<14 g/day for men, <7 g/day for women) are mandatory adjuncts. Continuous glucose monitoring (CGM)-guided lifestyle feedback and structured education programs (e.g., Diabetes Self-Management Education and Support, DSMES) significantly improve HbA1c, reduce hypoglycemia, and empower patients to make informed daily decisions.

Pharmacologic therapy is initiated when conservative measures fail to achieve glycemic targets (typically HbA1c <7.0% for most non-elderly adults; individualized per ADA/EASD guidelines). For Type 1 diabetes, lifelong exogenous insulin is indispensable: basal-bolus regimens (long-acting analogues like insulin glargine U300 or degludec combined with rapid-acting analogues such as lispro or aspart) or sensor-augmented pump therapy (including hybrid closed-loop systems) represent current standards. In Type 2 diabetes, metformin remains first-line unless contraindicated (e.g., eGFR <30 mL/min/1.73 m², severe hepatic impairment). Second-line agents are selected based on comorbidity profiles: SGLT2 inhibitors (e.g., empagliflozin, dapagliflozin) for patients with established atherosclerotic cardiovascular disease (ASCVD), heart failure, or chronic kidney disease (CKD); GLP-1 receptor agonists (e.g., semaglutide, dulaglutide) for those requiring weight loss, ASCVD risk reduction, or renal protection; and DPP-4 inhibitors (e.g., sitagliptin) for lower hypoglycemia risk in frail or elderly populations. Insulin therapy is escalated when oral/injectable agents fail—starting with basal insulin (e.g., insulin detemir), then progressing to basal-bolus or premixed regimens. Emerging agents—including dual GIP/GLP-1 receptor agonists (e.g., tirzepatide)—demonstrate superior glycemic and weight outcomes in clinical trials and are increasingly integrated into treatment algorithms.

Surgical treatment is reserved for select individuals with obesity-related Type 2 diabetes. Metabolic surgery—including Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), and biliopancreatic diversion with duodenal switch (BPD-DS)—is indicated for adults with BMI ≥40 kg/m² or BMI ≥35 kg/m² with inadequately controlled hyperglycemia despite optimal medical therapy. Surgery induces durable remission (defined as normoglycemia without antihyperglycemic medications for ≥1 year) in up to 60–80% of eligible patients, mediated by enhanced incretin secretion, improved hepatic insulin sensitivity, and reduced adipose inflammation. Preoperative endocrine evaluation, nutritional counseling, and psychiatric screening are mandatory. Postoperative care includes lifelong micronutrient supplementation (vitamin B12, iron, calcium, vitamin D), annual bone density assessment, and ongoing endocrinologic surveillance for glycemic relapse or nutritional deficiencies.

Treatment in China offers distinct advantages rooted in integrated healthcare infrastructure, technological innovation, and policy support. The National Health Commission’s 'Healthy China 2030' initiative prioritizes chronic disease prevention, enabling widespread access to subsidized glucometers, test strips, and insulin analogues via the National Reimbursement Drug List (NRDL). China leads globally in CGM adoption—domestic manufacturers (e.g., iHealth, Foresight) produce affordable, AI-enhanced real-time sensors with seamless integration into WeChat-based telehealth platforms. Endocrinology departments in tier-1 hospitals (e.g., Peking Union Medical College Hospital, Shanghai Ruijin Hospital) operate standardized diabetes centers accredited by the Chinese Diabetes Society (CDS), offering multidisciplinary teams (endocrinologists, certified diabetes educators, dietitians, podiatrists, ophthalmologists) under one roof. Tele-endocrinology services enable rural patients to consult specialists remotely, reducing disparities in care access. Moreover, large-scale pragmatic trials (e.g., the China Cardiometabolic Disease and Cancer Cohort Study) generate region-specific evidence guiding local treatment protocols—such as optimized insulin initiation thresholds in East Asian populations who exhibit greater insulin resistance at lower BMI thresholds.

Recovery and long-term management emphasize sustainability over short-term correction. Patients should perform home blood glucose monitoring as clinically indicated (e.g., multiple daily injections or insulin pump use), interpret trends—not isolated values—and adjust food/activity accordingly. Annual comprehensive assessments include dilated eye exams, urine albumin-to-creatinine ratio (UACR), estimated glomerular filtration rate (eGFR), monofilament foot screening, and lipid panel. Vaccinations (influenza, pneumococcal, hepatitis B, and now updated COVID-19 boosters) are critical given immune dysregulation in diabetes. Psychosocial well-being must be routinely addressed: depression and diabetes distress affect >20% of patients and correlate with poor adherence and outcomes. Family involvement, peer support groups, and culturally adapted mindfulness-based stress reduction programs improve resilience. Finally, patients should carry medical identification, understand sick-day rules (e.g., continuing insulin during illness, checking for ketones in Type 1), and maintain regular follow-up every 3–6 months—or more frequently if unstable. With consistent, evidence-based, and compassionate care, diabetes need not limit quality or longevity: it is a manageable condition where proactive partnership between patient and endocrinology team yields measurable, life-sustaining benefits.