DIABETES MELLITUS — COMPLETE MASTER NOTES (BEGINNER → EXAM LEVEL)

Diabetes mellitus

A chronic metabolic disorder characterized by persistent hyperglycaemia (high blood glucose levels), resulting from defects in insulin production, insulin action, or both. If not properly managed, diabetes can lead to severe complications affecting multiple organ systems.

Hyperglycaemia

A medical condition characterized by significantly elevated blood glucose levels, which can occur due to inadequate insulin response or secretion. Hyperglycaemia is a hallmark of diabetes and can result in serious health issues if not controlled.

Type 1 Diabetes Mellitus (T1DM)

An autoimmune form of diabetes where the immune system attacks and destroys insulin-producing β-cells in the pancreas. This results in absolute insulin deficiency, typically presenting in children and young adults, and requiring lifelong insulin therapy.

Type 2 Diabetes Mellitus (T2DM)

A common form of diabetes primarily resulting from insulin resistance, where the body's cells do not respond effectively to insulin, combined with relative insulin deficiency. It is often associated with obesity, sedentary lifestyle, and genetic predisposition, and can sometimes be managed through lifestyle changes alone.

Gestational Diabetes

A condition that occurs during pregnancy characterized by glucose intolerance leading to elevated blood sugar levels. It typically resolves after childbirth but may increase the risk of developing Type 2 diabetes later in life for both the mother and child.

Diabetic Ketoacidosis (DKA)

A critical and potentially life-threatening complication of diabetes that arises when there’s an insufficient supply of insulin, leading the body to break down fat for energy. This process results in the production of ketones, causing metabolic acidosis, which manifests through symptoms like nausea, vomiting, and altered consciousness.

Classic symptoms of Type 1 Diabetes

Often referred to as the '3 P's': Polyuria (frequent urination), Polydipsia (excessive thirst), and Polyphagia (increased hunger). These symptoms result from high glucose levels that affect kidney function and cellular energy availability.

Insulin resistance

A physiological condition wherein cells become less responsive to insulin, impairing glucose uptake and utilization. This leads to increased blood glucose levels and is often associated with obesity and Type 2 diabetes.

Acute complication of Type 2 Diabetes

Hyperosmolar Hyperglycaemic State (HHS) is an acute complication characterized by extremely high blood sugar levels without significant ketone production. It typically affects older adults with poorly controlled diabetes and can lead to severe dehydration and other critical health repercussions.

Microvascular complications of diabetes

Chronic complications involving small blood vessels that can lead to serious conditions such as diabetic retinopathy (vision loss), nephropathy (kidney failure), and neuropathy (nerve damage), significantly affecting the quality of life for diabetic patients.

Macrovascular complications of diabetes

Serious complications that affect larger blood vessels, leading to cardiovascular diseases such as coronary artery disease, strokes, and peripheral vascular disease, significantly increasing morbidity and mortality in diabetic patients.

Insulin's function in adipose tissue

Insulin promotes glucose uptake, encourages fat storage by stimulating lipogenesis, and inhibits lipolysis (fat breakdown), thereby playing a vital role in regulating energy balance and fat metabolism.

Insulin's role in muscle cells

Insulin facilitates glucose entry into muscle cells, fosters glycogen synthesis (storage form of glucose), and supports protein synthesis, making it essential for muscle development and energy management.

Insulin's effect on the liver

Insulin has multiple roles in the liver, including inhibiting gluconeogenesis (the creation of new glucose), promoting glycogen storage, and enhancing lipogenesis (fat storage). These actions collectively help maintain normal blood glucose levels.

Pathogenesis of Type 1 Diabetes

Type 1 Diabetes develops through a combination of genetic susceptibility, autoimmune destruction of insulin-producing β-cells, and environmental factors such as viral infections, leading to a lack of insulin production.

Symptoms of DKA

The clinical presentation of Diabetic Ketoacidosis includes symptoms such as vomiting, severe abdominal pain, Kussmaul breathing (deep, labored breaths), fruity-smelling breath due to ketones, and altered mental status, indicating a dangerous metabolic state.

Long-term complications of diabetes

Includes prolonged health issues resulting from uncontrolled diabetes, affecting both microvascular conditions (such as retinopathy and nephropathy) and macrovascular diseases (like coronary artery disease), which may arise from chronic exposure to high glucose levels.

Epidemiology of diabetes in Australia

Approximately 1.3 million Australians are diagnosed with diabetes, representing about 11% of total deaths in the country, highlighting a significant public health issue requiring effective management strategies.

Genetic factors in Type 2 Diabetes

Type 2 Diabetes shows a strong genetic component, reflected in high twin concordance rates (80-90%), suggesting that hereditary factors significantly contribute to the risk of developing this condition.

Environmental risk factors for Type 2 Diabetes

Contributing factors for Type 2 Diabetes include lifestyle-related issues such as obesity, physical inactivity, and poor dietary choices, which can elevate insulin resistance and increase the likelihood of developing the disease.