Diabetes + Endocrine Disorders Flashcards
Define diabetes mellitus
A chronic metabolic disease in which the body’s ability to produce or respond to the hormone insulin is impaired, resulting in abnormal metabolism of carbohydrates and hyperglycaemia
There are two main types of diabetes mellitus
Type 1 - Where the pancreas cannot produce insulin, this type is usually is diagnosed in childhood. Caused by either autoimmune or idiopathic B cell destruction
Type 2 - Develops due to prolonged hyperglycaemia in adults or adolescents, over time the bodies cells stop responding to insulin
Define diabetes insipidus
An endocrine disorder involving under secretion of ADH by hypothalamus, causing extreme thirst (polydipsia) and increased urination (polyuria)
What is the function of the pancreas?
Endocrine Function - Islets of langerhans cells secrete hormones (insulin and glucagon) into blood vessels to control blood glucose levels
Exocrine Function - Acinar cells secrete digestive enzymes into the pancreatic duct to help digest food (particularly protein)
Name some clinical features of type 1 diabetes mellitus
Sudden onset with severe symptoms of thirst and ketoacidosis.
Recent marked weight loss - Subject is usually lean.
Spontaneous ketosis
Requires insulin to sustain life
Absent c-peptide
Markers of auto-immunity present (e.g. islet cell antibodies)
Name some clinical features of type 2 diabetes mellitus
Usually insidious onset with associated fatigue, thirst, polyuria and nocturia.
Symptoms may be minimal and/or ignored by patient
No ketoacidosis
Usually overweight or obese with no associated weight loss.
Frequent infections e.g. urine, soft tissue, chest.
C-peptide detectable.
Other features of metabolic syndrome i.e. hypertension
What factors contribute to the development of type 2 diabetes?
Obesity
Hypertension
Hyperlipdemia
Smoking
Sedentary lifestyle
What is HbA1c a measure of?
The level of glucose adherence to haemoglobin over the last 3 months
What does a HbA1c result of 48 mmol/mol (6.5%) or greater mean?
A level of 48 mmol/mol or higher supports a diagnosis of diabetes
What is considered a normal HbA1c level for non-diabetic individual?
Below 42 mmol/mol (<6.0%)
What are the two main short term complications of type 1 diabetes?
Ketoacidosis and coma (Diabetic ketoacidosis or DKA)
Hypoglycaemia
What is DKA and why does it happen?
A state of severe uncontrolled diabetes caused by insulin deficiency, characterised by hyperglycaemia, hyperketonaemia (accumulation and elevation of circulating ketones) and metabolic acidosis (an increase in the hydrogen ion concentration that results in low serum bicarbonate levels)
The glucose in the blood stream of a type 1 diabetic goes largely unused since the absence of insulin means glucose cannot be transported into the cells for energy.
This condition means the body uses stored fat as an alternative means of energy.
This process produces acidic ketones, which then build up as ketones require insulin to break them down.
The presence of acidic ketones in the bloodstream causes the blood to more acidic than the body tissues, which creates a toxic condition.
What are some common DKA symptoms?
High blood sugar levels
Frequent urination (polyuria) and thirst
Fatigue and lethargy
Blurred vision
Vomiting & Nausea
Abdominal pain
Fruity odour to breath
Rapid, deep breathing
Muscle stiffness, aching or cramps
Coma (10% of cases)
What factors can precipitate DKA?
Infection
Insulin administration error or omission
Cardiovascular or cerebrovascular event (e.g MI or CVA)
Pancreatitis
Pulmonary embolism
Excessive alcohol consumption
Steroid use
What are the main 3 macro-vascular complications of diabetes mellitus?
Cardiovascular disease - MI, heart failure e.t.c
Cerebrovascular Disease - Stroke, cognitive impairment e.t.c
Peripheral Vascular Disease - Acute and chronic limb ischaemia, gangrene, amputation
What are the main 3 micro-vascular complications of diabetes mellitus?
Diabetic Retinopathy
Diabetic Nephropathy
Diabetic Neuropathy
What is the main pathological factor in the development of macro-vascular complications in diabetes?
Atherosclerosis - the formation of fatty plaques (atheroma) on the inner wall of an artery (tunica intima), the plaques harden over time and cause narrowing of the vessel (sclerosis)
What are the main pathological mechanisms involved in the development of micro-vascular diabetes complications?
The kidneys, retina and vascular endothelium are insulin independent tissues, meaning glucose moves freely across the cell membrane of these tissues regardless of the action of insulin - in diabetes this causes intracellular hyperglycaemia
Which causes…
Increased production of vascular endothelial growth hormone (VEGF)
Oxidative stress
Excessive sorbitol production (over-activation of the polyol pathway)
The non-enzymatic formation of advanced glycated end products (AGEs)
These mechanisms are thought to induce microvascular endothelial dysfunction - causing diabetic nephropathy, neuropathy and retinopathy