Diabetes Part 1: Pathophysiology and Diagnosis

Question 1

Where is insulin secreted from?

Answer 1

B cells in the Islets of Langerhans (endocrine pancreas)

Question 2

Describe the glucose metabolism pathway

Answer 2

• Increased glucose
• Insulin increases in response
• Increased glucose uptake by cells
• Decreased glucose in the serum

Question 3

Which gene has been found to be a cause of Type 1 DM?

Answer 3

Human Leukocyte Antigen (HLA)

Question 4

Describe the pathophysiology of Type 1 DM

Answer 4

• Autoimmune attack on pancreatic B cells
• Lymphocyte infiltration of islets and destruction of B cells
• Decreased insulin production

Question 5

Describe the aetiology of Type 1 DM

Answer 5

• ? environmental triggers
• ? bacteria in gut altered in infancy
• ?Viral infection

Question 6

Describe the aetiology of Type 2 DM

Answer 6

Combination of

• Reduced tissue sensitivity to insulin and
• Inability to secrete very high levels of insulin caused by:
• Expanded upper body visceral fat mass
• Increased intake of food and lack of exercise
• Peripheral insulin resistance
• Genetics (those for high end insulin secretion)

Question 7

Name some of the long term complications associated with diabetes

Answer 7

• Reduced life expectancy
• MI is the most common cause of death
• Acceleration of atherosclerosis (increases risk of coronary heart disease, MI and stroke)
• Arteriolar disease (kidneys, eyes, peripheral tissues and in arterioles supplying nerves)

Question 8

Describe how diabetes accelerates atherosclerosis

Answer 8

• Glucose attaches to LDL
• The glucose molecules stop LDL from binding to its receptor on liver cells tightly
• LDL is not removed by the liver cells
• Lipoprotein and lipids stay in the blood causing hyperlipidaemia

Question 9

Describe how diabetes causes small vessel disease (Hyaline change)

Answer 9

• The molecules flux into the subendothelial space but find it hard to flux back into the blood
• There is a build up of trapped molecules under the endothelial cell
• The basal lamina also becomes thickened
• This causes a narrow arteriole with poor blood flow which leads to ischaemia
• Increased connective tissue around capillaries (glycosylated collagen can then bind to albumin in the subendothelial space trapping it in the space) - cannot be reversed