DM

Diabetes Mellitus (DM)

Diabetes Mellitus (DM) is a group of metabolic disorders characterized by chronic hyperglycemia resulting from defects in insulin secretion, insulin action, or both. The chronic hyperglycemia of diabetes is associated with long-term damage, dysfunction, and failure of various organs, especially the eyes, kidneys, nerves, heart, and blood vessels.

Classification

Diabetes Mellitus is classified into several types:

• Type 1 Diabetes Mellitus (T1DM): This form results from autoimmune destruction of the insulin-producing beta cells in the pancreas, leading to absolute insulin deficiency. It is most commonly diagnosed in children and young adults.

• Type 2 Diabetes Mellitus (T2DM): This form is characterized by insulin resistance and relative insulin deficiency. It is the most common form of diabetes and is often associated with obesity, physical inactivity, and older age.

• Gestational Diabetes Mellitus (GDM): This form occurs during pregnancy and is characterized by glucose intolerance with onset or first recognition during pregnancy.

• Other Specific Types: These include monogenic diabetes syndromes, diseases of the exocrine pancreas (such as cystic fibrosis), and drug- or chemical-induced diabetes.

Pathophysiology

The pathophysiology of diabetes involves complex interactions between genetic, environmental, and lifestyle factors. In T1DM, the immune system mistakenly attacks and destroys beta cells, leading to insulin deficiency. In T2DM, insulin resistance in peripheral tissues and an inadequate compensatory insulin secretory response by pancreatic beta cells lead to hyperglycemia.

Diagnosis

The diagnosis of diabetes is based on plasma glucose criteria, either the fasting plasma glucose (FPG) level, the 2-hour plasma glucose (2-h PG) value during a 75-g oral glucose tolerance test (OGTT), or the A1C criteria.

• Fasting Plasma Glucose ≥ 126 mg/dL (7.0 mmol/L)
• 2-hour Plasma Glucose ≥ 200 mg/dL (11.1 mmol/L) during OGTT
• A1C ≥ 6.5%
• In a patient with classic symptoms of hyperglycemia or hyperglycemic crisis, a random plasma glucose ≥ 200 mg/dL (11.1 mmol/L)

Management

Management of diabetes involves lifestyle modifications, monitoring of blood glucose levels, and pharmacotherapy.

• Lifestyle Modifications: These include dietary changes, increased physical activity, and weight loss.

• Pharmacotherapy:

 * For T1DM, insulin therapy is essential.
 * For T2DM, oral hypoglycemic agents such as metformin, sulfonylureas, and newer agents like SGLT2 inhibitors and GLP-1 receptor agonists are used. Insulin may also be required.

• Monitoring: Regular monitoring of blood glucose levels and A1C is crucial to assess the effectiveness of treatment and make necessary adjustments.

Complications

Chronic complications of diabetes are divided into microvascular and macrovascular complications.

• Microvascular Complications:

 * Diabetic retinopathy
 * Diabetic nephropathy
 * Diabetic neuropathy

• Macrovascular Complications:

 * Cardiovascular disease
 * Cerebrovascular disease
 * Peripheral artery disease

Prevention

Prevention of diabetes, particularly T2DM, involves lifestyle interventions such as maintaining a healthy weight, engaging in regular physical activity, and consuming a balanced diet rich in whole grains, fruits, and vegetables.

See Also

• Insulin
• Hyperglycemia
• Hypoglycemia
• Metabolic syndrome

References

• American Diabetes Association. "Standards of Medical Care in Diabetes—2023." Diabetes Care, 2023.
• World Health Organization. "Global Report on Diabetes." WHO, 2016.