T1DM Flashcards
Where is insulin produced?
Beta cells in the Islets of Langerhans in the pancreas
What is the main function of insulin?
Reduces blood glucose by:
- Increasing cellular absorption of glucose
- Stimulates the liver and muscle cells to convert glucose to glycogen
Where is glucagon produced?
Alpha cells in the Islets of Langerhans in the pancreas
What is the function of glucagon?
Increases blood glucose (via glycogenolysis and gluconeogenesis)
What is ketogenesis? Why does this occur?
Ketogenesis is the conversion of fatty acids into ketones as an alternative source of fuel. It occurs when there is insufficient glucose supply and glycogen stores are exhausted.
In which circumstances does ketogenesis occur? Give examples.
- Fasting
- Low carb, high fat diets (“keto diet”)
- DKA
The main problems of diabetic ketoacidosis are…
- Ketoacidosis
- Dehydration
- Potassium imbalance
Describe the pathophysiology of diabetic ketoacidosis
- Cells are unable to absorb glucose due to lack of insulin
- Therefore the body initiates ketogenesis (conversion of fatty acids to ketones as an alternative source of fuel)
- Over time, both the blood glucose and ketones levels get higher and higher
- Initially the kidneys produce bicarbonate to counteract the ketones in the blood to maintain normal pH
- Over time, the ketones use up the bicarbonate and the blood becomes acidic (metabolic ketoacidosis)
Describe the pathophysiology of dehydration in DKA
- Hyperglycaemia results in glucose being filtered into the urine (glycosuria)
- The glucose in the urine draws water with it (osmotic diuresis) resulting in polyuria
- This results in severe dehydration (which in turn stimulates excessive thirst - polydipsia)
Describe the pathophysiology of potassium imbalance in DKA
- Insulin normally drives potassium into cells. In the absence of insulin this does not occur (so total body potassium is low)
- Serum potassium may be high or normal as the kidneys attempt to maintain potassium homeostasis
- When treatment with insulin starts, patients can develop severe hypokalaemia very quickly
What are the criteria for diagnosing DKA?
- Hyperglycaemia (i.e. blood glucose > 11 mmol/L)
- Ketosis (i.e. blood ketones > 3 mmol/L)
- Acidosis (i.e. pH < 7.3)
What are the symptoms of DKA?
- Polydipsia
- Polyuria
- N+V
- Altered consciousness
Typically, people in ketosis have a characteristic smell to their breath. What smell is this?
Acetone
How do you treat DKA?
Follow local protocol!!
Generally: FIG-PICK
- Fluids (IV fluid resus with normal saline, then follow protocol)
- Insulin infusion (fixed rate, e.g. Actrapid 0.1 units/kg/hour)
- Glucose - monitor and add a dextrose infusion if required (usually when BG <14)
- Potassium - monitor and correct as required
- Infection - investigate for potential triggers
- Chart fluid balance
- Ketones - monitor
How do you alter a diabetic patient’s normal insulin regime when treating DKA?
- Continue their usual long-acting insulin
- Hold their short-acting insulin
What is the maximum rate at which IV potassium can be infused?
Max rate = 10 mmol/hour
Generally, how often should patients with T1DM monitor their capillary blood glucose?
- On waking
- At each meal
- Before bed
Injecting insulin into the same spot can cause a condition called… What is this?
Lipodystrophy - this is where the subcutaneous fat hardens and patients will not absorb insulin properly from further injections into this spot
What are the two main short term complications of poorly controlled T1DM?
- Hypoglycaemia
- Hyperglycaemia (and DKA)
What are the typical symptoms of hypoglycaemia?
More severe hypoglycaemia can lead to…
- Tremor
- Sweating
- Irritability
- Dizziness
- Pallor
More severe hypoglycaemia can lead to reduced consciousness, coma and death
What is the cut-off value for hypoglycaemia?
Blood glucose less than 4 mmol/L (four is the floor)
Describe the management of hypoglycaemia in a patient who is…
- Able to eat/drink
- Unable to eat/drink, but has a cannula
- Unable to eat/drink and does NOT have a cannula
- Fast-acting glucose, e.g. dextrose tablets followed by slow-acting carbohydrates such as biscuits/toast
- IV glucose, e.g. 100ml 20% glucose
- IM glucagon
What are the long term complications of poorly controlled T1DM? How can these complications be classified?
Microvascular:
- Diabetic neuropathy, nephropathy and retinopathy
Macrovascular:
- IDH and MI
- Stroke
- Hypertension
Infection-related complications:
- Bacterial, e.g. skin/soft tissue infections, UTIs
- Fungal, e.g. candidiasis
How is T1DM monitored long term?
How often should this be done?
HbA1c
Every 3-6 months
How does Flash Glucose Monitoring (FreeStyle Libre) work?
It uses a sensor on the skin to measure the glucose level of the interstitial fluid
Is it still necessary to do a capillary blood glucose measurement in a patient with suspected hypoglycaemia, even if their FreeStyle Libre is showing a normal glucose level?
Yes - capillary blood glucose is still required as their is a 5 minute lag with the FreeStyle Libre
