Diabetes Mellitus Flashcards
What is diabetes?
When blood glucose is too high (hyperglycaemia)
What are the long term effects of hyperglycaemia?
Causes damage to small and large blood vessels
What is the result of damage to blood vessels due to hyperglycaemia?
Premature death from cardiovascular diseases
How is the problem of diabetes developing?
Huge and growing problem, cost to society is high and escalating
Why may the problem of diabetes be worse than anticipated?
High proportions to diabetes cases undiagnosed
What type of diabetes constitutes most of those that are undiagnosed?
Type 2
Why can type 2 diabetes go undiagnosed?
Because you can be quite well with diabetes for many years with blood sugars only marginally raised
What is the problem with undiagnosed diabetes?
Even with only small blood sugar elevations, over time damage is caused to the blood vessels
What are the potential causes of blood glucose rising in diabetes?
- Inability to produce insulin due to ß-cell failure and/or
- Insulin resistance preventing insulin working effectively- it doesn’t work at the receptor
What are the most important and common types of diabetes mellitus?
1 and 2
What are all types of diabetes mellitus characterised by?
Hyperglycaemia, other many other metabolic abnormalities present as well
How does diabetes mellitus present?
- Typical symptoms of hyperglycaemia
- Symptoms of inadequate energy production
What are the typical symptoms of hyperglycaemia?
- Polyuria
- Polydipsia
- Blurring of vision
- Urogenital infections
Why does hyperglycaemia cause blurring of vision?
Glucose comes out into the vitreous humour, altering the refractive index
Give an example of a urogenital infection common in hyperglycaemia
Thrush
What are symptoms of energy utilisation?
NAME?
What does the severity of symptoms of diabetes depend on?
NAME?
What must be obtained prior to diagnosing diabetes?
Laboratory confirmation
What tests can be used to diagnose diabetes?
- Fasting blood glucose
- Oral glucose tolerance test
- HbA1 c (in type 2 only)
What do you do in an oral glucose tolerance test?
Give 75g glucose to drink after fasting, and take sample after 2 hours
What does the HbA1 c test measure?
The amount of glucose attached to RBCs
What do you need to confirm diabetes?
- Symptoms and 1 abnormal test or
- Asymptomatic and 2 abnormal tests
Will a diabetic patient always test positive for all 3 tests?
No
What are the diagnostic criteria for diabetes?
- Fasting venous plasma glucose; ≥7.0 mmol/l
- Random venous plasma glucose; ≥11.1 mmol/l
- Elevated HbA1 c; ≥6.5%
- Oral glucose tolerance test; fasting venous plasma glucose≥7.0 mmol/l and/or 2 hrvenous plasma glucose; ≥11.1 mmol/l
When is oral glucose tolerance test used?
Rarely, except for in pregnancy
What causes type 1 diabetes?
An absoloute insulin deficiency due to autoimmune and non-autoimmune destruction of ß cells
What causes type 2 diabetes?
Insulin deficiency and insulin resistance
What types, other than 1 and 2, of diabetes mellitus are there?
- Genetic defects of ß-cells
- Genetic defects of insulin action
- Drug-induced diabetes
- Associated with other hormone disorders
- Iron overload-haemochromatosis
- After pancreatectomy
What percentage of diabetes cases are type 1?
5-10%
How fast are ß-cells destroyed in type 1 diabetes?
Variable- can be very rapid to years
What is present in type 1 diabetes?
Antibodies; islet-cell and GAD 65
When does type 1 diabetes develop?
90% diagnosed under 30 years old, but can occur at any time
How has the prevalence of type 1 diabetes changed?
It has doubled ever 20 years since 1945
What is the aetiology of type 1 diabetes?
Not fully understood
What proves type 1 diabetes is not all genetic predisposition?
Twin studies
How does type 1 diabetes present?
- Rapid onset symptoms (usually weeks)
- Weight loss
- Polyuria
- Polydipsia
- In late presentation, may be vomiting due to ketoacidosis
Describe the typical patient presenting with type 1 diabetes
- Usually (not always) young-
What is insulins action on glucose metabolism?
- Enhances uptake of glucose by liver, muscle and adipose tissue
- Inhibits liver glycogen breakdown
What is insulins actions on fat metabolism?
- Promotes clearance of free fatty acids
- Prevents lipolysis
What is insulins effect on amino acid metabolism?
- Active transport of amino acids into cells
- Inhibits catabolism of proteins
- Inhibits gluconeogenesis in liver
What does insulin deficiency cause?
- Lipolysis
- Hyperglycaemia
What is the result of lipolysis caused by insulin deficiency?
Increase in free fatty acids, therefore an increase in ketones, causing acidosis, which leads to cardiovascular collapse
What does hyperglycaemia cause?
Hyperosmolarity and glucosuria
What does glucosuria cause?
Electrolyte losses (particularly sodium and potassium) and dehydration
What does dehydration cause?
Renal failure
How is a vicious cycle set up with dehydration causing renal failure?
The renal failure causes further dehydration
What does the renal failure cause?
Shock, which causes cardiovascular collapse
What are the clinical signs of type 1 diabetes?
NAME?
How is the presence of ketones in urine most easily measured?
Ketostick
What does presence of ketones in urine signify?
An absolute lack of insulin
How is type 1 diabetes treated?
Exogenous insulin
How is exogenous insulin given?
By subcutaneous injection several times a day
Why is diabetes treatment a specialised field?
The amounts and type of insulin required is dependant upon many factors
What happens if a type 1 diabetes diagnosis is missed?
Severe consequences- death, sometimes in hours
What should an ideal insulin do?
Mimic the characteristics of normal insulin
What is the pathology of type 2 diabetes?
Dual pathology- insulin resistance and relative insulin lack
What is the aetiology for type 2 diabetes?
Both causes have separate possible aetiologies- genetic and environmental factors
What is the most common single cause of insulin resistance?
Obesity
What shows that type 2 diabetes has genetic factors?
Twin studies
What factors have caused the type 2 diabetes epidemic?
Environmental, not genetic
Why does obesity lead to type 2 diabetes?
- Obesity leads to insulin resistance first
- This causes an increased secretion of inslin
- Eventually the pancreas can’t keep up, causing pancreas exhaustion
- Hyperglycaemia develops
- As the pancreas is going at full speed, it is unable to accelerate- first phase secretion is lost and then basal insulin secretion
- Amyloid type deposits in the islet cells, causing ß-cell failure
What happens after bariatric surgery or a very low calorie diet?
- Within 7 days, fasting blood glucose normalises in type 2 diabetes before any weight loss
- Massive fall in liver fat content and return of normal insulin sensitivity
- Over 8 weeks, first phase insulin release and maximal rates of insulin release return to normal
- This change is in step with decreasing pancreatic fat content normalising ß cell function
What does the effect of bariatric surgery or very low calories on type 2 diabetes mean?
It can be considered as a potentially reversible metabolic disorder precipitated by chronic intraorgan fat
What causes the improvements in glucose and insulin resistance following bariatric surgery or very low calorie diets?
- Calorific intake falls immediately post measure
- Sudden reversal of traffic into the fat stores brings about profound change in intracellular concentration of fat metabolites
- Under hypocalorific conditions, fat is mobilised first from the liver and other ectopic sites rather than from visceral or subcutaneous sites
- Fasting glucose improved because of an 81% decrease in liver fat content and normalisation of hepatic insulin sensitivity
How does type 2 diabetes present?
Very variable symptoms
- May have polyuria, polydipsia, weight loss
- May be asymptomatic
Why are type 2 diabetes symptoms variable?
Because slower rise in blood glucose
How can type 2 diabetes be discovered when the patient is asymptomatic?
On routine screening
How old are type 2 diabetes patients
Usually, though not universally, older- most over 40, but seen increasingly in younger people and children
What % of type 2 diabetes patients are overweight/obese?
90%
Diagnostically, how can type 2 diabetes be differentiated from type 1?
Absence of ketones in urine
What does the absence of ketones in urine signify?
ß-cells are still producing some insulin, though not enough to control glucose levels
What happens if type 2 diabetes if left untreated?
- Gradual worsening of symptoms
- Worsening/onset of complications of diabetes
What are the problems with gradual worsening/onset of diabetes complications?
- Significant morbidity
- Mortality
- Financial cost
Does a patient require diabetic control if they are asymptomatic?
Yes
How is type 2 diabetes treated
NAME?
What lifestyle factor can be used to treat type 2 diabetes?
Exercise
What effect does exercise have on type 2 diabetes?
Improves insulin sensitivity
Give 8 drug therapies used for the treatment of type 2 diabetes
- Biguandines
- Sulphonylureas
- Thiazolidinediones
- DPP4 inhibitors
- α-glucosidase inhibitors
- SGLTs
- GLP1 analogues
- Insulin
How are patients with diabetes monitored?
NAME?
