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Understanding Diabetes Mellitus: Diagnosis and Classification
Definition and Description of Diabetes Mellitus
Diabetes Mellitus is a group of metabolic diseases characterized by chronic hyperglycemia due to defects in insulin secretion, insulin action, or both. This persistent high blood sugar can lead to long-term damage, dysfunction, and failure of various organs, particularly the eyes, kidneys, nerves, heart, and blood vessels .
Pathogenesis and Metabolic Abnormalities
The development of diabetes involves several pathogenic processes, ranging from autoimmune destruction of pancreatic beta-cells, leading to insulin deficiency, to abnormalities causing insulin resistance. The core issue in diabetes is the deficient action of insulin on target tissues, which results from either inadequate insulin secretion or diminished tissue responses to insulin .
Symptoms and Acute Complications
Symptoms of marked hyperglycemia include polyuria (frequent urination), polydipsia (excessive thirst), weight loss, polyphagia (excessive hunger), and blurred vision. Chronic hyperglycemia can also impair growth and increase susceptibility to infections. Acute, life-threatening consequences of uncontrolled diabetes include hyperglycemia with ketoacidosis or the nonketotic hyperosmolar syndrome .
Long-term Complications
Long-term complications of diabetes are extensive and include:
- Retinopathy: Potential loss of vision.
- Nephropathy: Leading to renal failure.
- Peripheral Neuropathy: Risk of foot ulcers, amputations, and Charcot joints.
- Autonomic Neuropathy: Causing gastrointestinal, genitourinary, cardiovascular symptoms, and sexual dysfunction.
- Cardiovascular Diseases: Increased incidence of atherosclerotic cardiovascular, peripheral arterial, and cerebrovascular diseases.
- Hypertension and Lipoprotein Metabolism Abnormalities: Commonly found in diabetic patients .
Classification of Diabetes Mellitus
Diabetes is broadly classified into two main types:
Type 1 Diabetes
Type 1 diabetes is characterized by an absolute deficiency of insulin secretion. It is often identified by serological evidence of an autoimmune process occurring in the pancreatic islets and genetic markers. Individuals with type 1 diabetes require insulin for survival due to the extensive destruction of beta-cells .
Type 2 Diabetes
Type 2 diabetes is more prevalent and results from a combination of resistance to insulin action and an inadequate compensatory insulin secretory response. This type can remain asymptomatic for a long period, during which abnormal carbohydrate metabolism can be detected through plasma glucose measurements. Management may include weight reduction, exercise, and oral glucose-lowering agents, though some individuals may eventually require insulin .
Diagnostic Criteria
Diabetes is diagnosed based on blood or plasma glucose levels:
- A random plasma glucose level ≥ 200 mg/dL with classic symptoms.
- A fasting plasma glucose level ≥ 126 mg/dL.
- A 2-hour plasma glucose level ≥ 200 mg/dL after an oral glucose challenge of 75 g on two occasions.
Impaired Glucose Tolerance and Impaired Fasting Glycaemia
Impaired Glucose Tolerance (IGT) and Impaired Fasting Glycaemia (IFG) are conditions where blood glucose levels are above normal but below the diagnostic threshold for diabetes. These conditions indicate a higher risk of developing diabetes and its complications.
Conclusion
Diabetes Mellitus is a complex group of metabolic disorders with significant health implications. Understanding its classification, pathogenesis, and diagnostic criteria is crucial for effective management and prevention of its acute and long-term complications. Early detection and appropriate treatment strategies can significantly improve the quality of life for individuals with diabetes.
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