Diabetes Mellitus and Related Pathophysiology

Flashcards covering the definition, classifications (Type 1, Type 2, Gestational, Secondary), pathogenesis, clinical manifestations, laboratory values, and chronic/acute complications of Diabetes Mellitus.

Diabetes Mellitus

A disorder of glucose metabolism related to absent or insufficient insulin supply or poor utilization of the insulin that is available.

Type 1 Diabetes Mellitus

Formerly known as juvenile-onset or insulin-dependent diabetes, it involves autoimmune destruction of $\beta$ cells leading to an absolute insulin deficit; it most often occurs in people younger than 30 years of age.

Type 2 Diabetes Mellitus

The most prevalent type of diabetes where the pancreas produces some endogenous insulin, but it is either insufficient for the body's needs or is poorly utilized by the tissues (insulin resistance).

Metabolic Syndrome

A cluster of at least three medical conditions (Abdominal obesity, Hypertension, High Glucose, High Triglycerides, Low HDL) that increases the risk of developing cardiovascular diseases and Type 2 Diabetes.

Prediabetes

An intermediate stage where glucose levels are higher than normal but not yet at diagnostic levels for diabetes; includes Impaired Fasting Glucose (IFG) and Impaired Glucose Tolerance (IGT).

Impaired Fasting Glucose (IFG)

A prediabetic state where fasting glucose levels are between $6.1\text{--}6.9\,mmol/L$.

Impaired Glucose Tolerance (IGT)

A prediabetic state where 2-hour plasma glucose levels are between $7.8$ and $11\,mmol/L$.

Hemoglobin A1C (HbA1C) Goal

The clinical target for glucose control in diabetic patients is typically less than $7\%$, while prediabetes is indicated by a range of $6\%$ to $6.4\%$.

Insulitis

A direct T-cell attack on pancreatic $\beta$-cells that occurs in the pathogenesis of Type 1 Diabetes Mellitus.

Molecular Mimicry

A process where foreign antigens structurally mimic $\beta$-cell antigens, causing the immune system to attack both the foreign and self-antigens.

Adipokines

Inflammatory mediators (e.g., $TNF\alpha$) released from adipose tissue that contribute to insulin resistance.

Lipotoxicity

A state where free fatty acids (FFAs) inhibit the function of GLUT2 on $\beta$-cells, decreasing glucose import and $\beta$-cell recognition of high blood glucose.

Gestational Diabetes

Diabetes that develops during pregnancy and is detected at $24\text{--}28$ weeks of gestation; patients have a $5\text{--}10\%$ risk of developing Type 2 diabetes within $5\text{--}10$ years.

Secondary Diabetes

Abnormal blood glucose levels caused by other medical conditions (e.g., Cushing’s syndrome, Cystic fibrosis) or treatments (e.g., Corticosteroids like prednisone).

Hypoglycemia

Low blood glucose characterized by symptoms such as shaking, sweating, dizziness, anxiousness, hunger, and fast heartbeat; often described as 'cold and clammy'.

Hyperglycemia

High blood glucose characterized by the '3 Ps' (polydipsia, polyphagia, polyuria), extreme thirst, dry skin, and blurry vision; often described as 'hot and dry'.

Polyuria

Increased frequency and volume of urination caused by osmotic diuresis when the kidney is unable to reabsorb filtered glucose.

Polydipsia

Excessive thirst resulting from hyperosmolarity in blood and tissues and stimulation of osmoreceptors in the hypothalamus.

Polyphagia

Increased hunger or excessive eating because the body's cells are 'starved' of glucose due to insulin deficiency or resistance.

Diabetic Retinopathy

A microvascular complication of diabetes resulting in abnormal permeability and ischemia of retinal vessels due to chronic hyperglycemia.

Diabetic Nephropathy

Kidney damage characterized by glomerular hyperfiltration, basement membrane thickening, and albuminuria, which may eventually lead to a decreased glomerular filtration rate (GFR).

Diabetic Polyneuropathy

Nerve damage resulting from hyperglycemia-induced ischemia and impaired peripheral nerve repair, often causing sensory loss in a 'glove and stocking' pattern.

Charcot Foot

A progressive and destructive arthropathy involving the collapse of the foot arch and destruction of weight-bearing joints associated with neurovascular disease in diabetics.

Diabetic Ketoacidosis (DKA)

An acute complication typically seen in Type 1 DM involving absolute insulin deficit, leading to ketogenesis, metabolic acidosis (anion gap), and Kussmaul respirations.

Hyperosmolar Hyperglycemic State (HHS)

An acute complication of Type 2 DM characterized by severe hyperglycemia, high serum osmolarity, and prominent neurologic symptoms without significant ketosis.

Kussmaul Respiration

Deep, fast breathing seen in DKA as a compensatory mechanism to blow off $CO_2$ and offset metabolic acidosis.

Glucosuria

The presence of glucose in the urine, which occurs when blood glucose levels exceed the renal threshold of approximately $12\,mmol/L$.