Flashcards in Diabetes Testing Deck (10):
What different tests do we have for DM?
- Random Glc test
- Fasting Glc test
- HbA1c test
- Oral Glucose Tolerance Test (OGTT)
- Blood & Urine Ketones
- Urine glucose
All DM tests are indicative of DM, which tests are considered diagnostic and what values would indicate diabetes?
Fasting Venous Plasma Glc > 7mmol/l
Random Venous plasma Glc > 11.1mmol/l
OGTT >11.1mmol/l after 2 hours
HbA1C > 48mmol/mol
Explain how the OGTT works
1) Take a fasting glucose
2) Give them oral glucose load
3)Test again after 2 hours
If its still raised then its +ve for diabetes (should normally return to normal within 1 hour of ingesting glucose)
What do we need to diagnose Diabetes Mellitus?
2 +ve diagnostic tests (fasting or random glucose, OGTT or HbA1c)
1 +ve diagnostic test + Symptoms
Explain what HbA1c is?
It forms from haemoglobin and plasma Glc.
The amount that forms is directly proportional to the amount of Glc in the blood.
So HbA1c level tells you the average amount of glucose in the blood over the last few weeks
In what groups can't we use HbA1c tests?
- Children or young people
- Pregnant women
- The acutely ill
- Meds that affect glucose e.g. CCS or antipsychotics
- Acute pancreatic damage
- renal Failure
- HIV infection
Basically anything that would alter recent glucose levels renders HbA1c useless
How would you diagnose DKA?
By the specific presentation and blood/urine ketone testing.
Describe the biochem results of a patient with DKA?
1) High glucose
2) Low Bicarbonate (kessmauls resp)
3) Low Na+ (diluted by movement of water)
4) High urea, potassium & Creatinine (dehydration reduces excretion)
When would you want to test C-peptide?
lets say a patient is having repetitive hypos.
You test their insulin levels to see if thats the source and its raised.
C-peptide will tell you if they have factitious anaemia (excess insulin administered) or an insulinoma (excess insulin production)