Diabetes and hypoglycaemia

Question 1

Describe the homeostasis of blood glucose, its distribution, control by insulin, counter-regulatory hormones

Answer 1

After a meal, glucose levels rise in the blood

In response, the pancreas releases insulin, which facilitates glucose uptake into cells, where it can be utilized for energy or stored as glycogen or fat

When blood glucose levels are low, the pancreas releases glucagon

Glucagon promotes the breakdown of glycogen (glycogenolysis) in the liver to release glucose back into the bloodstream

Control by Insulin:

Insulin is a hormone secreted by the beta cells in the pancreas when blood glucose levels rise

Insulin signals to the body’s cells, particularly muscle and fat cells, to take up glucose from the bloodstream

It also inhibits the liver from producing glucose

Thus, insulin helps lower blood glucose levels

insulin binds to the insulin receptor, a transmembrane protein on many cells

This initiates a signal transduction cascade that results in the translocation of glucose transporter type 4 (GLUT4) to the cell surface, allowing glucose to enter the cell

Counter-Regulatory Hormones:

Several hormones act in opposition to insulin to raise blood glucose levels. These include glucagon, epinephrine (also known as adrenaline), cortisol, and growth hormone

1) Glucagon: Secreted by alpha cells of the pancreas, glucagon acts on the liver to promote glycogenolysis and gluconeogenesis, thus increasing blood glucose level

2) Epinephrine: This hormone is produced by the adrenal glands in response to hypoglycemia or stress. It stimulates glycogenolysis and gluconeogenesis and also inhibits insulin secretion

3) Cortisol: This is a steroid hormone produced by the adrenal cortex. It promotes gluconeogenesis and inhibits glucose uptake by tissues, raising blood glucose levels. Its effects are more long-term compared to glucagon and epinephrine

4) Growth hormone: Produced by the pituitary gland, growth hormone has indirect effects on glucose homeostasis. It promotes the release of free fatty acids from adipose tissue, which can be used as an alternate energy source, sparing glucose. It also has an anti-insulin effect, reducing peripheral glucose uptake and increasing hepatic glucose output

Question 2

Explain hyperglycaemia (DM)

Answer 2

Hyperglycaemia refers to higher than normal levels of glucose in the blood

The term is most often associated with diabetes mellitus (DM), a metabolic disorder characterised by chronic hyperglycaemia

Type 1 Diabetes:

• absolute insulin deficiency
• usually arises due to autoimmune destruction of the insulin-producing beta cells in the pancreas
• Without insulin, glucose cannot be transported into cells and accumulates in the bloodstream, resulting in hyperglycaemia
• Hence the need to take insulin regularly to manage their blood glucose levels

Type 2 Diabetes:

• Insulin resistance, a condition in which body’s cells do not respond properly to insulin and cannot easily absorb glucose from the bloodstream
• a condition in which body’s cells do not respond properly to insulin and cannot easily absorb glucose from the bloodstream

The main symptoms of diabetes mellitus and hyperglycaemia include increased thirst (polydipsia), frequent urination (polyuria), extreme hunger (polyphagia), unexplained weight loss, fatigue, blurred vision, and slow-healing sores or frequent infections

Chronic hyperglycaemia, if left untreated, can lead to serious complications, affecting almost every system in the body

E.g. cardiovascular diseases, nerve damage (neuropathy), kidney damage (nephropathy), eye damage (retinopathy), foot damage, skin conditions, hearing impairment, and even Alzheimer’s disease

Question 3

Define Hypoglycaemia and its causes

Answer 3

Hypoglycaemia refers to a condition where the level of glucose (sugar) in your blood drops below a certain point (typically below 70 mg/dL, although the exact number can vary)

Causes:

1) Medication:

• Certain medications, particularly insulin or sulfonylureas used in the treatment of diabetes, can cause hypoglycaemia if too much is taken relative to the amount of food eaten or physical activity performed

2) Diet:

• Skipping meals, eating less than normal, or eating food with less carbohydrate than normal can contribute to low blood glucose levels

3) Alcohol:

• Drinking alcohol, especially on an empty stomach, can cause hypoglycaemia, as alcohol inhibits the liver’s ability to release glucose into the bloodstream

4) Physical activitiy:

• Physical activity uses up glucose in the blood. If this is not balanced with adequate food intake, hypoglycaemia can result

Other medical conditions:

• Some non-diabetic related conditions can also cause hypoglycaemia, including some types of liver disease, kidney disorders, certain types of gastric surgery, and endocrine problems like adrenal or pituitary insufficiency

Symptoms:

often include feelings of shakiness, dizziness, sweating, hunger, irritability or moodiness, anxiety or nervousness, and headache

More severe hypoglycaemia can lead to confusion, blurred/impaired vision, seizures, and loss of consciousness