Diabetes Mellitus — Revision Notes

⚡ 30-Second Revision

Diabetes Mellitus (DM): — Chronic hyperglycemia.
Types: — Type 1 (T1DM), Type 2 (T2DM), Gestational (GDM).
T1DM: — Autoimmune destruction of pancreatic beta cells → absolute insulin deficiency.
T2DM: — Insulin resistance + progressive beta-cell dysfunction → relative insulin deficiency.
Insulin: — Lowers blood glucose, promotes glucose uptake, glycogenesis.
Glucagon: — Raises blood glucose, promotes glycogenolysis, gluconeogenesis.
Symptoms (3 Ps): — Polyuria, Polydipsia, Polyphagia, Weight loss (T1DM).
Diagnostic Criteria:

- FPG $ge 126,\text{mg/dL}$ - 2-hr OGTT $ge 200,\text{mg/dL}$ - HbA1c $ge 6.5$ - Random PG $ge 200,\text{mg/dL}$ (with symptoms)

Microvascular Complications: — Retinopathy, Nephropathy, Neuropathy.
Macrovascular Complications: — CAD, Stroke, PAD.
Metformin: — Reduces hepatic glucose production, improves insulin sensitivity.

2-Minute Revision

Diabetes Mellitus is a metabolic disorder characterized by high blood glucose levels. The two main types are Type 1 and Type 2. Type 1 Diabetes is an autoimmune condition where the body's immune system destroys the insulin-producing beta cells in the pancreas, leading to a complete lack of insulin.

It typically starts in childhood or adolescence and requires lifelong insulin injections. Type 2 Diabetes, the more common form, involves insulin resistance, where cells don't respond effectively to insulin, and a gradual decline in the pancreas's ability to produce enough insulin.

It's often linked to lifestyle factors like obesity and usually develops in adulthood. Common symptoms for both types include increased urination (polyuria), thirst (polydipsia), and hunger (polyphagia).

Diagnosis relies on blood tests like fasting plasma glucose, oral glucose tolerance test, and HbA1c. Uncontrolled diabetes can lead to severe complications affecting the eyes, kidneys, nerves, and heart.

Management involves lifestyle changes and medications, including insulin or oral drugs like Metformin.

5-Minute Revision

Diabetes Mellitus (DM) is a chronic condition defined by persistent hyperglycemia, stemming from issues with insulin production, action, or both. Insulin, secreted by pancreatic beta cells, is crucial for lowering blood glucose by facilitating cellular uptake and promoting glycogen storage. Glucagon, from alpha cells, counteracts this by raising blood glucose.

Type 1 Diabetes (T1DM) is an autoimmune disease where beta cells are destroyed, leading to absolute insulin deficiency. It typically presents acutely in younger individuals with symptoms like polyuria, polydipsia, polyphagia, and weight loss, often leading to diabetic ketoacidosis (DKA). Treatment is lifelong insulin.

Type 2 Diabetes (T2DM) is more common, characterized by insulin resistance and progressive beta-cell failure. It's strongly associated with obesity and physical inactivity, usually developing gradually in adults. Symptoms are similar but often milder. Management starts with lifestyle changes, followed by oral hypoglycemic agents (e.g., Metformin, which reduces liver glucose production and improves insulin sensitivity) and eventually insulin if needed.

Gestational Diabetes (GDM) occurs during pregnancy due to placental hormone-induced insulin resistance and usually resolves postpartum, though it increases the risk of future T2DM.

Diagnosis involves: Fasting Plasma Glucose (FPG) $ge 126,\text{mg/dL}$, 2-hour Oral Glucose Tolerance Test (OGTT) $ge 200,\text{mg/dL}$, or HbA1c $ge 6.5$.

Long-term complications are severe: Microvascular (retinopathy, nephropathy, neuropathy) and Macrovascular (coronary artery disease, stroke, peripheral artery disease). Effective management aims to keep blood glucose within target ranges to prevent these complications.

Prelims Revision Notes

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Definition: — Diabetes Mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia.
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Pancreas: — Endocrine gland containing islets of Langerhans.

* Beta cells: Secrete Insulin (lowers blood glucose). * Alpha cells: Secrete Glucagon (raises blood glucose).

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Insulin Action: — Anabolic hormone. Promotes glucose uptake by muscle/adipose tissue (via GLUT4), stimulates glycogenesis (liver/muscle), inhibits gluconeogenesis/glycogenolysis.
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Glucagon Action: — Catabolic hormone. Stimulates glycogenolysis (liver), gluconeogenesis (liver).
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Types of Diabetes:

* Type 1 DM (T1DM): * Cause: Autoimmune destruction of pancreatic beta cells. * Insulin: Absolute deficiency. * Onset: Usually acute, in children/young adults. * Symptoms: Polyuria, Polydipsia, Polyphagia, Weight loss, fatigue.

* Complication: High risk of Diabetic Ketoacidosis (DKA). * Treatment: Lifelong exogenous insulin. * Type 2 DM (T2DM): * Cause: Insulin resistance + progressive beta-cell dysfunction.

* Insulin: Relative deficiency (initially normal/high, then declines). * Onset: Usually gradual, in adults (increasingly in youth). * Risk Factors: Obesity, physical inactivity, genetics.

* Complication: Hyperosmolar Hyperglycemic State (HHS). * Treatment: Lifestyle changes, oral hypoglycemic agents, insulin (if needed). * Gestational DM (GDM): * Cause: Glucose intolerance during pregnancy due to placental hormones causing insulin resistance.

* Course: Usually resolves postpartum, but increases risk of T2DM later.

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Cardinal Symptoms (3 Ps): — Polyuria (frequent urination), Polydipsia (increased thirst), Polyphagia (increased hunger).
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Diagnostic Criteria (any one confirms DM):

* Fasting Plasma Glucose (FPG): $ge 126,\text{mg/dL}$ ($ge 7.0,\text{mmol/L}$) * 2-hour Oral Glucose Tolerance Test (OGTT): Plasma glucose $ge 200,\text{mg/dL}$ ($ge 11.1,\text{mmol/L}$) after 75g glucose load. * HbA1c: $ge 6.5$ * Random Plasma Glucose: $ge 200,\text{mg/dL}$ (with classic symptoms).

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Prediabetes: — FPG $100-125,\text{mg/dL}$, 2-hr OGTT $140-199,\text{mg/dL}$, HbA1c $5.7$.
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Complications:

* Microvascular: Diabetic Retinopathy (eyes), Diabetic Nephropathy (kidneys), Diabetic Neuropathy (nerves). * Macrovascular: Coronary Artery Disease (CAD), Stroke, Peripheral Artery Disease (PAD).

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Key Medications (T2DM):

* Metformin: Reduces hepatic glucose production, improves insulin sensitivity. * Sulfonylureas: Stimulate insulin secretion. * SGLT2 Inhibitors: Increase glucose excretion in urine.

Vyyuha Quick Recall

3 Ps of Diabetes:

Pee a lot (Polyuria) Prinkly (Polydipsia - very thirsty) People (Polyphagia - very hungry)

T1DM vs T2DM - 'A' for Absolute, 'R' for Resistance:

T1DM: Autoimmune, Absolute insulin deficiency, Always needs insulin. T2DM: Resistance to insulin, Relative insulin deficiency, Related to lifestyle.