Biology 12 - Diabetes

Pancreas role in blood glucose regulation

The pancreas maintains blood glucose homeostasis by secreting insulin and glucagon from the islets of Langerhans.

Islets of Langerhans

The endocrine portion of the pancreas containing alpha cells (glucagon) and beta cells (insulin).

Insulin (Biology 12 level)

A peptide hormone that lowers blood glucose by promoting cellular glucose uptake and glycogenesis in the liver and muscle cells.

Insulin mechanism of action

Binds to cell membrane receptors, increasing glucose transport into cells and stimulating conversion of glucose to glycogen in liver and muscle.

Stimulus for insulin secretion

Elevated blood glucose levels (e.g., after a meal).

Glucagon (Biology 12 level)

A peptide hormone that raises blood glucose by stimulating glycogenolysis and gluconeogenesis in the liver.

Glucagon mechanism of action

Binds to liver cell receptors, triggering breakdown of glycogen to glucose and release into the bloodstream.

Stimulus for glucagon secretion

Low blood glucose levels (e.g., fasting or exercise).

Negative feedback in blood glucose control

Insulin and glucagon work in a negative feedback loop to maintain blood glucose within a narrow range (~4–7 mmol/L).

Homeostasis of blood glucose

Maintenance of stable internal glucose concentration through hormonal regulation by the pancreas.

Diabetes mellitus overview

A chronic metabolic disorder characterized by persistent hyperglycemia due to defects in insulin production or action.

Hyperglycemia definition

Abnormally high blood glucose levels due to insufficient insulin or insulin resistance.

Hypoglycemia definition

Abnormally low blood glucose levels, often caused by excess insulin or missed meals.

Type 1 diabetes (pathophysiology)

An autoimmune disorder in which pancreatic beta cells are destroyed, resulting in little or no insulin production.

Type 1 diabetes onset

Typically develops in childhood or adolescence but can occur at any age.

Type 1 diabetes treatment

Requires lifelong insulin replacement via injections or insulin pump.

Type 2 diabetes (pathophysiology)

A metabolic disorder characterized by insulin resistance and eventual decline in insulin production.

Insulin resistance

Target cells (especially muscle and liver) fail to respond effectively to insulin, reducing glucose uptake.

Type 2 diabetes onset

More common in adults but increasingly seen in younger individuals due to lifestyle factors.

Type 2 diabetes treatment

Managed through diet, exercise, oral medications (e.g., metformin), and sometimes insulin therapy.

Gestational diabetes

A temporary form of diabetes that develops during pregnancy due to hormonal insulin resistance.

Gestational diabetes outcome

Often resolves after childbirth, but increases risk of developing Type 2 diabetes later in life.

Symptoms of diabetes

Polyuria (frequent urination), polydipsia (excessive thirst), polyphagia (increased hunger), fatigue, blurred vision, and weight loss (especially Type 1).

Polyuria in diabetes

High blood glucose exceeds renal threshold, causing glucose to be excreted in urine and water to follow by osmosis.

Polydipsia in diabetes

Excessive urination leads to dehydration and increased thirst response.

Fatigue in diabetes

Cells are unable to effectively uptake glucose, reducing available energy for cellular respiration.

Long-term complications of diabetes

Microvascular and macrovascular damage including cardiovascular disease, nephropathy, neuropathy, and retinopathy.

Cardiovascular complications

Increased risk of atherosclerosis, heart attack, and stroke due to blood vessel damage.

Poor wound healing in diabetes

Reduced blood flow and nerve damage impair healing, increasing risk of infection and amputation.

Blood glucose monitoring

Regular measurement of blood glucose levels using glucometers or continuous glucose monitoring (CGM) systems.

Insulin therapy

External administration of insulin to regulate blood glucose in individuals with insufficient endogenous production.

Insulin pump

A device that delivers controlled, continuous insulin doses to mimic pancreatic function.

Lifestyle management in Type 2 diabetes

Includes balanced diet, regular physical activity, weight management, and blood glucose monitoring.

Exercise and glucose regulation

Physical activity increases glucose uptake by muscle cells and improves insulin sensitivity.