Overview of diabetes mellitus

Prof. Dr. Tran Huu Dang

1. Definition and Classification

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Insulin is a hormone secreted by the beta cells of the pancreas, playing a crucial role in regulating glucose, lipid, and protein metabolism in the body. When insulin is insufficiently produced or functions inefficiently, glucose cannot enter cells to generate energy, leading to its accumulation in the bloodstream and causing hyperglycemia.

Diabetes is currently considered one of the most prevalent non-communicable diseases globally, with a rapidly increasing trend, particularly in developing countries, including Vietnam. This rise is closely linked to lifestyle changes, urbanization, an aging population, and increasing obesity rates.

Classification of Diabetes

According to the classification by the American Diabetes Association (ADA), diabetes is divided into the following main groups:

1. Type 1 diabetes:
   This form of the disease is caused by an autoimmune mechanism, in which the body’s immune system destroys the beta cells of the pancreas, leading to an absolute insulin deficiency. The disease typically manifests in children or young adults, progresses rapidly, and can present as ketoacidosis. Patients are strictly required to undergo lifelong insulin therapy.
2. Type 2 diabetes:
   Accounts for approximately 90–95% of all cases. The disease is characterized by insulin resistance combined with progressive impairment of beta-cell function. Type 2 diabetes is commonly found in adults, particularly those who are overweight, obese, physically inactive, and have a genetic predisposition. The disease develops silently for many years before being diagnosed.
3. Gestational diabetes:
   A condition of hyperglycemia first recognized during pregnancy, usually occurring in the second or third trimester. Although glucose levels return to normal after delivery in most cases, these women are at a higher risk of developing type 2 diabetes in the future, and the condition also affects fetal health.
4. Other specific types:
   Includes diabetes due to monogenic causes (MODY), diseases of the exocrine pancreas (chronic pancreatitis, pancreatic cancer), drug-induced diabetes (corticosteroids, antipsychotic drugs), or other endocrine disorders.

2. Symptoms and Diagnosis

Clinical Symptoms

Diabetes, especially type 2, can progress silently for many years without explicit symptoms. When they manifest, classic symptoms include:

• Polyuria (frequent urination)
• Polydipsia (excessive thirst)
• Polyphagia (increased appetite) accompanied by unexplained weight loss
• Fatigue and reduced capacity for labor
• Blurred vision
• Recurrent infections (skin, urinary tract, genital tract)

In some cases, the disease is only detected after the emergence of complications such as myocardial infarction, stroke, or kidney failure.

Diagnostic Criteria

According to the ADA 2024–2026, the diagnosis of diabetes is confirmed when any of the following criteria are met (repeat testing is required for confirmation in the absence of unequivocal symptoms):

1. HbA1c ≥ 6.5%
2. Fasting plasma glucose (FPG) ≥ 126 mg/dL (≥ 7.0 mmol/L)
3. 2-hour plasma glucose value during an oral glucose tolerance test ≥ 200 mg/dL (≥ 11.1 mmol/L)
4. A random plasma glucose ≥ 200 mg/dL in a patient with classic symptoms of hyperglycemia

In addition, the concept of prediabetes is also very important, defined by the presence of any of the following criteria:

• HbA1c: 5.7–6.4%
• FPG: 5.6 – 6.9mmol/L (100–125 mg/dL)
• 2-hour plasma glucose value during an oral glucose tolerance test ≥ 7.8 – 11 mmol/L

This is a window where effective interventions can be implemented to prevent progression to full-blown disease.

3. Complications: The Real Danger

Diabetes does not cause immediate mortality, but the long-term consequences of chronic hyperglycemia are extremely severe. Complications are the primary cause of disability and death in diabetic patients.

Macrovascular Complications

• Coronary artery disease: Myocardial infarction, heart failure
• Cerebrovascular disease: Ischemic or hemorrhagic stroke
• Peripheral arterial disease: Limb ischemia, ulceration, gangrene

Patients with diabetes have a 2- to 4-fold higher risk of cardiovascular disease compared to non-diabetic individuals.

Microvascular Complications

• Diabetic retinopathy: The leading cause of blindness among working-age adults
• Diabetic kidney disease: Leading to chronic kidney failure, requiring dialysis or kidney transplantation
• Neuropathy: Causing numbness, pain, and loss of sensation → foot ulcers, carrying a high risk of amputation

Additionally, other complications include erectile dysfunction, cognitive decline, and severe infections.

4. Recent Updates in Treatment (2024–2026)

In recent years, the management strategy for diabetes has shifted fundamentally. The objective is no longer limited merely to glycemic control but is directed toward organ protection, particularly the heart and kidneys.

Modern Pharmacotherapy

• SGLT2 inhibitors (SGLT2i): Help promote glucose excretion via urine, while reducing the risk of heart failure and slowing the progression of kidney disease.
• GLP-1 receptor agonists (GLP-1 RA): Increase glucose-dependent insulin secretion, promote weight loss, and reduce cardiovascular risk.

These two classes of medications are now recommended for early use in patients with high cardiovascular risk or established kidney disease.

Technology in Management

• CGM (Continuous Glucose Monitoring): Continuously monitors glucose levels, providing real-time data
• AID (Automated Insulin Delivery): Automated insulin pump systems integrated with continuous glucose sensors

These technologies help individualize therapy and minimize the risk of hypoglycemia.

Individualized Glycemic Targets

The HbA1c target should be tailored to each individual:

• Young patients with few comorbidities: <6.5%
• Elderly patients with multiple underlying conditions: 7.5–8.0%
• In general: < 7% is acceptable.

This approach balances the benefits of glycemic control against the risk of hypoglycemia.

5. Lifestyle Management: The “Three-Legged Stool” of Treatment

Diabetes management cannot be successful if it relies solely on medication. Lifestyle modification is the core, sustainable foundation.

1. Proper Nutrition

• Prioritize foods with a low glycemic index
• Increase intake of green vegetables and dietary fiber
• Limit simple sugars, sugary beverages, and refined carbohydrates
• Control portion sizes

2. Physical Activity

• At least 150 minutes/week of moderate-intensity physical activity
• Combine aerobic exercise with resistance training
• Reduce prolonged sedentary time

3. Weight Management

• A 5–10% reduction in body weight can significantly improve insulin resistance
• In some cases, diabetes remission can be achieved

Conclusion

Diabetes is a chronic condition, but it can be completely and effectively managed. Advances in modern medicine, particularly novel medications and glucose monitoring technologies, have significantly improved patient prognoses. However, the deciding factors remain patient awareness, treatment adherence, and lifestyle modifications.

Diabetes management is a long-term journey that demands close collaboration among patients, families, and healthcare professionals. With a comprehensive and individualized approach, patients can fully enjoy a healthy life, prevent complications, and enhance their quality of life.

References

1. American Diabetes Association (ADA). Standards of Care in Diabetes—2026. Diabetes Care.
2. Ministry of Health of Vietnam. Guidelines for the Diagnosis and Treatment of Type 2 Diabetes Mellitus (Decision 5481/QD-BYT).
3. International Diabetes Federation (IDF). IDF Diabetes Atlas, 10th Edition.