Endocrinology Conditions Flashcards
What is the body’s ideal blood glucose concentration
Between 4.4 and 6.1 mmol/l
What is insulin
An anabolic hormone produced by the beta cells in the islets of Langerhans in the pancreas that reduces blood sugar levels
Insulin is essential in letting cells take glucose out of the blood and use it as fuel, without insulin the cells cannot do this
How does insulin reduce blood sugar
In two ways:
- Causes cells in the body to absorb glucose from the blood and use it as fuel
- Causes muscle and liver cells to absorb glucose from the blood and store it as glycogen
What is glucagon
An catabolic hormone produced by the alpha cells in the islets of Langerhans in the pancreas that is released in response to low blood sugar levels and stress, and tells the liver to break down stored glycogen into glucose (glycogenolysis) and also to convert protein and fats into glucose (gluconeogenesis)
What is type 1 diabetes
Type 1 diabetes mellitus (T1DM) is a disease where the pancreas stops being able to produce insulin.
When there is no insulin being produced, the cells of the body cannot take glucose from the blood and use it for fuel
Therefore the cells think the body is being fasted and has no glucose supply
Meanwhile the level of glucose in the blood keeps rising causing hyperglycaemia
What causes type 1 diabetes
This is unclear
May be a genetic component
May be triggered by certain viruses such as Coxsackie B virus and enterovirus
What is diabetic ketoacidosis
Occurs in type 1 diabetes where the person is not producing adequate insulin themselves and is not injecting adequate insulin to compensate for this
It occurs when the body does not have enough insulin to use and process glucose
The main problems, and most dangerous, are ketoacidosis, dehydration and potassium imbalance
What is ketoacidosis
As the cells in the body have no fuel and think they are starving they initiate the process of ketogenesis so that they have a usable fuel. Over time the patient gets higher and higher glucose and ketones levels. Initially the kidneys produce bicarbonate to counteract the ketone acids in the blood and maintain a normal pH. Over time the ketone acids use up the bicarbonate and the blood starts to become acidic.
How do patients become dehydrated in DKA
Hyperglycaemia overwhelms the kidneys and glucose starts being filtered into the urine. The glucose in the urine draws water out with it in a process called osmotic diuresis. This causes the patient to urinate a lot (polyuria). This results in severe dehydration. The dehydration stimulates the thirst centre to tell the patient to drink lots of water. This excessive thirst is called polydipsia.
How do patients with DKA have a potassium imbalance
Insulin normally drives potassium into cells. Without insulin potassium is not added to and stored in cells. Serum potassium can be high or normal as the kidneys continue to balance blood potassium with the potassium excreted in the urine, however total body potassium is low because no potassium is stored in the cells. When treatment with insulin starts patients can develop severe hypokalaemia (low serum potassium) very quickly and this can lead to fatal arrhythmias.
How does DKA present
Life threatening medical emergency: Hyperglycaemia Dehydration Ketosis Metabolic acidosis (with a low bicarbonate) Potassium imbalance
The patient will therefore present with symptoms of these abnormalities:
- Polyuria
- Polydipsia
- Nausea and vomiting
- Acetone smell to their breath
- Dehydration and subsequent hypotension
- Altered Consciousness
- They may have symptoms of an underlying trigger (i.e. sepsis)
How is DKA diagnosed
Hyperglycaemia (i.e. blood glucose > 11 mmol/l)
Ketosis (i.e. blood ketones > 3 mmol/l)
Acidosis (i.e. pH < 7.3)
How is DKA treated
FIG-PICK
F – Fluids – IV fluid resuscitation with normal saline (e.g. 1 litre stat, then 4 litres with added potassium over the next 12 hours)
I – Insulin – Add an insulin infusion (e.g. Actrapid at 0.1 Unit/kg/hour)
G – Glucose – Closely monitor blood glucose and add a dextrose infusion if below a certain level (e.g. 14 mmol/l)
P – Potassium – Closely monitor serum potassium (e.g. 4 hourly) and correct as required
I – Infection – Treat underlying triggers such as infection
C – Chart fluid balance
K – Ketones – Monitor blood ketones (or bicarbonate if ketone monitoring is unavailable)
Establish patient on their normal sub-cut insulin regime prior to stopping insulin and fluid infusion
What is the maximum infusion rate of potassium
10mmol per hour
What is the long term management of type 1 diabetes
Condition is life long so patient education is essential
Components of treatment are:
-Subcutaneous insulin regimes
-Monitoring dietary carbohydrate intake
-Monitoring blood sugar levels on waking, at each meal and before bed
-Monitoring for and managing complications, both short and long term
Insulin is usually prescribed as a combination of a background, long acting insulin given once a day and a short acting insulin injected 30 minutes before intake of carbohydrate (i.e. at meals). Insulin regimes are initiated by a diabetic specialist.
What is lipodystrophy
Injecting into the same spot can cause a condition called “lipodystrophy”, where the subcutaneous fat hardens and patients do not absorb insulin properly from further injections into this spot. For this reason patients should cycle their injection sites.
What are the short term complications of type 1 diabetes
Short term complications relate to immediate insulin and blood glucose management:
- Hypoglycaemia
- Hyperglycaemia (and DKA)
What is hypoglycaemia
Low blood sugar level Typical symptoms are: -Tremor -Sweating -Irritability -Dizziness -Pallor
More severe hypoglycaemia will lead to: -Reduced consciousness -Coma -Death (unless treated.)
What are the potential long term complications of type 1 diabetes
Chronic exposure to hyperglycaemia causes damage to the endothelial cells of blood vessels. This leads to leaky, malfunctioning vessels that are unable to regenerate. High levels of sugar in the blood also causes suppression of the immune system, and provides an optimal environment for infectious organisms to thrive.
Macrovascular Complications:
- Coronary artery disease is a major cause of death in diabetics
- Peripheral ischaemia causes poor healing, ulcers and “diabetic foot”
- Stroke
- Hypertension
Microvascular Complications:
- Peripheral neuropathy
- Retinopathy
- Kidney disease, particularly glomerulosclerosis
Infection Related Complications:
- Urinary Tract Infections
- Pneumonia
- Skin and soft tissue infections, particularly in the feet
- Fungal infections, particularly oral and vaginal candidiasis
What is HbA1c
It is counting glycated haemoglobin, which is how much glucose is attached to the haemoglobin molecule. This is considered to reflect the average glucose level over the last 3 months because red blood cells have a lifespan of around 3-4 months. We measure it every 3 – 6 months to track progression of the patient’s diabetes and how effective the interventions are. It requires a blood sample sent to the lab, usually red top EDTA bottle.
What is flash glucose monitoring
Eg. FreeStyle Libre
This uses a sensor on the skin that measures the glucose level of interstitial fluid. There is a lag of 5 minutes behind blood glucose. This sensor records the glucose readings at short intervals so you get a really good impression of what the glucose levels are doing over time. The user needs to use a “reader” to swipe over the sensor and it is the reader that shows the blood sugar readings.
What is the pathology of type 2 diabetes
Repeated exposure to glucose and insulin makes the cells in the body become resistant to the effects of insulin. It therefore requires more and more insulin to produce a response from the cells and get them to take up and use glucose. Over time, the pancreas (specifically the beta cells) becomes fatigued and damaged by producing so much insulin and they start to produce less. A continued onslaught of glucose on the body in light of insulin resistance and pancreatic fatigue leads to chronic hyperglycaemia. Chronic hyperglycaemia leads to microvascular, macrovascular and infectious complications
What are the risk factors for type 2 diabetes
Older age Ethnicity (Black, Chinese, South Asian) Family history Obesity Sedentary lifestyles High carbohydrate (particularly refined carbohydrate) diet
How does type 2 diabetes present
Sometimes caught on HbA1c screen Fatigue Polydipsia and polyuria (thirsty and urinating a lot) Unintentional weight loss Opportunistic infections Slow healing Glucose in urine (on dipstick)
What is the oral glucose tolerance test (OGTT)
An oral glucose tolerance test (OGTT) is performed in the morning prior to having breakfast. It involves taking a baseline fasting plasma glucose result, giving a 75g glucose drink and then measuring plasma glucose 2 hours later. It tests the ability of the body to cope with a carbohydrate meal.
How is pre-diabetes diagnosed
Pre-diabetes can be diagnosed with a HbA1c or by “impaired fasting glucose” or “impaired glucose tolerance”. Impaired fasting glucose means that their body struggles to get their blood glucose levels in to normal range, even after a prolonged period without eating carbohydrates. Impaired glucose tolerance means their body struggles to cope with processing a carbohydrate meal.
- HbA1c – 42-47 mmol/mol
- Impaired fasting glucose – fasting glucose 6.1 – 6.9 mmol/l
- Impaired glucose tolerance – plasma glucose at 2 hours 7.8 – 11.1 mmol/l on an OGTT
How is type 2 diabetes diagnosed
Diabetes can be diagnosed if the patient fits the criteria on plasma glucose, an oral glucose tolerance test or HbA1c.
HbA1c > 48 mmol/mol
Random Glucose > 11 mmol/l
Fasting Glucose > 7 mmol/l
OGTT 2 hour result > 11 mmol/l
How is type 2 diabetes managed
It is curable
Dietary Modification
- Vegetables and oily fish
- Typical advice is low glycaemic, high fibre diet
- A low carbohydrate may in fact be more effective in treating and preventing diabetes but is not yet mainstream advice
Optimise Other Risk Factors
- Exercise and weight loss
- Stop smoking
- Optimise treatment for other illnesses, for example hypertension, hyperlipidaemia and cardiovascular disease
Monitoring for Complications
- Diabetic retinopathy
- Kidney disease
- Diabetic foot
What are the HbA1c treatment targets
48 mmol/mol for new type 2 diabetics
53 mmol/mol for diabetics that have moved beyond metformin alone
How is type 2 diabetes medically managed
First line: metformin titrated from initially 500mg once daily as tolerated.
Second line add: sulfonylurea, pioglitazone, DPP-4 inhibitor or SGLT-2 inhibitor. The decision should be based on individual factors and drug tolerance.
Third line: Triple therapy with metformin and two of the second line drugs combined, or;
Metformin plus insulin
What are the types of insulin
Rapid-acting Insulins
- These start working after around 10 minutes and last around 4 hours
- Novorapid
- Humalog
- Apidra
Short-acting Insulins
- These start working in around 30 minutes and last around 8 hours
- Actrapid
- Humulin S
- Insuman Rapid
Intermediate-acting Insulins
- These start working in around 1 hour and last around 16 hours
- Insulatard
- Humulin I
- Insuman Basal
Long-acting Insulins
- These starts working in around 1 hour and lasts around 24 hours:
- Lantus
- Levemir
- Degludec (lasts over 40 hours)
Combinations Insulins
- These contain a rapid acting and an intermediate acting insulin. In brackets is the proportion of rapid to intermediate acting insulin:
- Humalog 25 (25:75)
- Humalog 50 (50:50)
- Novomix 30 (30:70)
