Diabetes Mellitus: Historical Perspective, Classification, Epidemiology, And Pathophysiology.pdf

Etymology:
Diabetes mellitus, translating to 'honey sweet flow', originated from ancient practices where physicians would diagnose the condition by tasting a patient's urine, distinguishing it from diabetes insipidus by its sweetness.

Classification (1997 WHO/ADA):
- Type 1 Diabetes: Typically manifests in childhood or adolescence, but can also develop in adults. It involves complete insulin deficiency due to autoimmune destruction of pancreatic beta cells.
- Type 2 Diabetes: Predominantly a disease of the elderly, yet rates are rising among younger demographics due to obesity. It is characterized by insulin resistance and relative insulin deficiency.
- Other forms include gestational diabetes (pregnancy diabetes), pancreas resection diabetes, and rare genetic diabeteses.

Epidemiology:
- Approximately 90% of patients have Type 2 diabetes.
- Global prevalence: around 150 million cases, projected to double in the next 20 years, significantly impacting developing countries like India and China.
- In the USA, one in three individuals is expected to develop Type 2 diabetes.

Pathophysiology:
- Normal Glucose Regulation: Glucose derived from food or synthesis in the liver (gluconeogenesis) is transported via blood, taken up by cells for energy, and stored as glycogen. Insulin, secreted by pancreatic beta cells, regulates this process.
- Insulin Resistance: The majority of Type 2 diabetics exhibit insulin resistance, where cells are less responsive to insulin's effects, leading to hyperglycemia.
- Type 1 Diabetes: An autoimmune disease causing complete insulin deficiency and requiring lifelong insulin replacement therapy.
- Type 2 Diabetes: A multifactorial disease influenced by both genetics (e.g., Pima Indians) and lifestyle factors like obesity and diet. Insulin resistance, impaired secretion, and increased hepatic glucose production contribute to hyperglycemia.

Diagnosis and Symptoms:
- Diagnosis involves blood tests for fasting plasma glucose levels or oral glucose tolerance testing.
- Early symptoms are often nonspecific, including increased thirst, frequent urination, weight loss, fatigue, and blurred vision.