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What is diabetes mellitus?

Disorder that arises when the threshold of insulin required to maintain normal glucose levels is lost

Serum glucose levels rise


What happens normally in out body when glucose levels rise?

1. Insulin is released by beta cells
2. Promotes uptake of glucose by the liver, adipose tissue and muscles
3. Suppresses gluconeogeneis
4. Promotes glycogenesis and lipogenesis


What happens if blood glucose rises but insulin is not around?

Release of intermediates FFA and amino acids
Favours gluconeogenesis

Positively regulated by cortisol and growth hormone in stress situations


What are the characteristics of insulin?

Short acting if shot when eating

Longer acting if shot during the night - suppresses ketogenesis and promotes anabolic pathways

Short half life - extended by protamine and zinc


What are the symptoms of diabetes?

1. Polyuria and dehydration - increase in plasma glucose increases osmolarity of the urine in the tubules. More water is lost due to osmolar load

2. Recurrent infections - high glucose concentration stimulates growth of microbed

3. Blurred vision - osmolar load affects vision

4. Weight loss - glucose and carbohydrate stores are used ineffectively in the absence of insulin


What is ketoacidosis?

Since diabetic patients are unable to use carbohydrate stores effectively, patients get increase lipolysis

Lipolysis = increased beta oxidation of fatty acids

This liberates ketone bodies that are effective at generating energy, but in the process leads to acidosis


What is diabetic ketoacidosis?

Accumulation of ketone bodies from increased lipolysis and dehydration

Contributes to electrolyte problems

Intracellular potassium is exchanged for hydrogen ions that accumulate extracellularly in acidosis.

Dehydration drives potassium out of the body due to activation of renin-angiotensin system -> exchanges sodium for potassium

Patients present with very low potassium levels and loss of up to 10% of water


What is the treatment for diabetic ketoacidosis?


Insulin - stimulates active uptake of potassium into the cells


What does Diabetes Mellitus mean in Greek?

Much sweet urine


What kind of syndrome is Diabetes Mellitus?

Covers several syndromes of abnormal carbohydrate metabolism


What is the one characteristic shared by all the syndromes under the umbrella term DM?



What are the features of Type II diabetes mellitus?

Non-insulin dependent diabetes

Insulin resistance and pancreatic failure

Usually develops over 30 years of age

Most patients are overweight


What are the features of Type I diabetes mellitus?

Insulin dependent diabetes

Relative or absolute impairment of insulin secretion by the pancreas

Possible at any age

Autoimmune destruction of the pancreatic gland


What tests are commonly performed in a diabetic clinic?

Lipid profiles
Blood sugar
Blood pressure


Diagnostic criteria of diabetes?

Have to have diabetes symtoms PLUS test within diabetic range in clinical tests


What are diabetes symptoms?

Polyuria - large urine volume

Polydipsia - thirst

Unexplained weight loss - calories lost in urine


Whatr are clinical tests done to diagnose diabetes?

Fasting venous plasma more or equal to 7 mmol/L

Random venous plasma glucose more or equal to 11.1 mmol/L

HbALe - glycated haemoglobin

Oral glucose tolerance test - 2 hour plasma glucose more or equal to 11.1 after 75g of glucose


What is glycated haemoglobin?

Haemoglobin reacts with glucose in RBC becoming glycated

This is a non-enzymatic reaction

Enhanced when blood glucose is high for a long time

Clinicians are able to get overall picture of what average glucose levels have been for months/ years


What is the oral glucose tolerance test?

Glucose is given and blood samples are taken to determine how quicky it is cleared from the blood

1. Baseline blood sample is drawn
2. Patient is given a measured dose of glucose solution to drink within 5 minutes
3. Blood is drawn at intervals for measurements of glucose

Simple diabetes screening - most important blood sample = 2 hour mark