Week 1 - Diabetes mellitus

Question 1

Features of type 1 diabetes

Answer 1

1. Is rapidly fatal if not treated
2. Characterised by progressive loss of all most of the pancreatic B cells
3. Commonest type in the young
4. Must be treated with insulin

Question 2

Features of type 2 diabetes:

Answer 2

1. Characterised by slow progressive loss of B cells but with disorders of insulin secretion and tissue resistance to insulin
2. May be present for a long time before diagnosis

Question 3

Cause for Type 1 diabetes:

Answer 3

Likely that a genetic predisposition to the disease interacts with an environmental trigger to produce immune activation
This leads to production of killer lymphocytes and macrophages and antibodies that attack and progressively destroy B cells.
Genetic predisposition associated with genetic markers: HLA DR3, HLA DR4
Strong seasonal variation: suggesting link with a viral infection acting as a trigger to rapid deterioration

Question 4

Symptoms of type 1 diabetes:

Answer 4

1. Polyuria: excess urine production
   In diabetes, where large quantities of glucose in the blood are filtered by the kidney not all of this glucose is reabsorbed. The extra glucose remains in the nephron tubule. This places an extra osmotic load on the nephron, and means that less water is reabsorbed to maintain the isosmotic character of this section of the nephron. The extra water remains with the glucose in the nephron tubule and is excreted as copious urine.
2. Thirst: polydipsia: due to excess water loss and osmotic effects of glucose on the thirst centres
3. Weight loss: fat and protein are metabolised by tissues because insulin is absent

Question 5

Diagnosis of Type 1 diabetes:

Answer 5

1. Measurement of plasma glucose levels
2. High blood glucose: appearance of glucose in the urine (glycosuria)
3. If not dealt with urgently, these individuals will progress to a life-threatening crisis: diabetic ketoacidosis
4. Fasting glucose
5. Oral glucose tolerance test
6. HbA1c
7. Elevated venous plasma glucose
8. Presence of ketones (breakdown products of fats)- easily measured in urine using “ketostik”

Question 6

Symptoms of Type 2 diabetes:

Answer 6

1. Lack of energy
2. Persistent infections: particularly thrush infections of the genitalia, or infections of the feet
3. Slow healing minor skin damage
4. Visual problems
5. Classical triad of symptoms: polyuria, polydipsia, weight loss

Question 7

Management of Type 1 diabetes:

Answer 7

1. Cannot be cured and must be managed
2. Insulin used - must be injected; exogenous insulin used - subcutaneous injection several times/day
3. In cases of infection or trauma: insulin dosage needs to be increased otherwise there is a risk of diabetic ketoacidosis
4. Appropriate dietary management
5. Regular exercise
6. Frequent blood glucose measurement
7. Risk of hypoglycaemia: can occasionally be fatal unless treated with glucose either by mouth or infusion

Question 8

Management/treatment of Type 2 diabetes:

Answer 8

1. Can sometimes be managed by diet
2. Oral hypoglycaemic drugs such as sulphonylureas that increase insulin release from remaining B cells and reduce insulin resistance
3. Metformin that reduces gluconeogenesis
4. Appropriate dietary management and regular exercise

Question 9

Macrovascular clinical complications of diabetes in long-term diabetics:

Answer 9

1. Increased risk of stroke
2. Increased risk of myocardial infarction
3. Poor circulation to the periphery - especially the feet

Question 10

Microvascular complications of diabetes in long-term diabetics:

Answer 10

1. Diabetic eye disease:
   -changes in the lens due to osmotic effects of glucose (glaucoma)
   -cataracts
   -Diabetic retinopathy: damage of blood vessels in the retina which can lead to blindness;
   damaged blood vessels may leak and form protein exudates on the retina or they can rupture and cause bleeding to the eye.
   In addition, new vessels may form (proliferative retinopathy): these vessels are very weak and can easily bleed
2. Diabetic kidney disease (nephropathy):
   -damage to the glomeruli
   -poor blood supply because of changes in the kidney blood vessels
   -damage from infections of the urinary tract
   -An early sign of nephropathy: increase in the amount of protein in the urine (microalbuminuria)
3. Diabetic neuropathy:
   -Damage to peripheral nerves
   -Changes or a loss of sensation
   -Changes due to alteration in the function of the autonomic nervous system
4. Diabetic feet:
   -Poor blood supply
   -Damage to nerves and increased risk of infection –> make feet of diabetics vulnerable
   -Possible loss of feet through gangrene

Question 11

Diabetes mellitus

Answer 11

• Group of metabolic disorders characterised by chronic hyperglycaemia (elevated blood glucose concentration)
• Over years leads to damage of small and large blood vessels causing premature death from cardiovascular disease

Question 12

What causes insulin resistance to develop in Type 2 diabetes?

Answer 12

1. Obesity - in particular, central obesity
2. Muscle and liver fat deposition
3. Elevated circulating free fatty acids