Diabetes 2 Flashcards
What can be measured by Urine Analysis in Diabetic Patients?
Detection of glucose in urine (glycosuria)
- Usually used as first line screening test
- Normally plasma glucose would have to be >10 mmol/L for glucose to be detected in urine. Can be detected using basic urine test strip / dipstick
- Test strips directly placed into urine – different colour responses reflect glucose concentration
Detection of ketones in urine (ketonuria)
- Can have qualitative detection using urine test strips/ dipstick
- Test strips will not detect β-hydroxybutyric acid
- Ketones may be present in normal individuals
What is Microalbuminuria?
Defined as excretion of 30-300 mg of Albumin/24hrs
- Urine dipsticks are not sensitive enough at this concentration. Measurement important for diabetic patient.
- Signals of early reversible renal damage
What is commonly measured for Microalbuminuria?
Albumin to creatinine ratio (ACR) commonly measured
- More convenient than 24hr urine collection
- NICE recommend early morning urinary ACR
- Upper limit of normal: 2.5 mg/mmol in men, 3.5 mg/mmol in women
What is used to estimate Blood Glucose?
Venous plasma glucose
- Some laboratories accept serum samples for monitoring
- Samples should be analysed quickly
- Glucose 10-15% higher in plasma / serum than whole blood
What are 2 types of Blood Analysis?
Fasting glucose sample
- Glucose measured after at least 8 hours overnight fast
- Generally considered a more reliable sample than random glucose
- Can be used for diagnosis (see criteria)
Random glucose sample
- Measured at any time regardless of fasting state
- Usually measured during emergency situations
- Can also be used for diagnosis (see criteria)
How is the Oral Glucose Tolerance Test carried out?
Used mainly in pregnant women to test for gestational diabetes. Sometimes used in patients have borderline results
Before the test
- Three days of unrestricted diet and usual exercise
- An evening meal (30 – 50g carbohydrate) consumed night before
- An overnight fast of 8 – 14 hours is required
The Test
- Fasting plasma glucose taken first (am)
- Patient drinks 75g of anhydrous glucose dissolved in 250 – 300 ml water over 5 minutes
- Second plasma glucose taken 2 hours
What are considerations for OGTT?
- No smoking during the test
- Patient should rest during the test
- Medications / infections at the time of the test should be recorded
- Glucose must be measured in laboratory
How is diagnosis of diabetes using HbA1c?
- Diabetes Mellitus: ≥48 (in the presence of symptoms). If asymptomatic repeat within 2wks
- High risk: 42 - 48(monitor annually)
- Low risk / Normal: ≤ 41
What is Impaired Fasting Glucose?
Fasting plasma glucose ≥ 6.1 and < 7.0 mmol/L and 2hr OGTT <7.8 mmol/L
- Intermediate state between normal glucose tolerance and diabetes
- Presents in 5% of the population and increasing with age
- Increased risk of micro and macrovascular complications
What is Impaired Glucose Tolerance?
Fasting plasma glucose < 7.0 mmol/L and OGTT 2hr ≥ 7.8 mmol/L but < 11.1 mmol/L
- Intermediate state between normal glucose tolerance and diabetes
- Individuals often manifest hyperglycaemia only when challenged with oral glucose in an OGTT
- 2-5% of people with IGT per year progress to diabetes
- IGT associated with increased risk of developing cardiovascular disease
What is the criteria for diagnosis of Diabetes?
If patient has clinical symptoms (Polyuria, polydipsia or weight loss)
- A single random venous plasma glucose of ≥ 11.1 mmol/L
or
- Fasting venous plasma glucose of ≥ 7.0 mmol/L
or
- 2 hour plasma glucose in OGTT ≥ 11.1 mmol/L is diagnostic
If patient DOES NOT have clinical symptoms
- At least two elevated plasma glucose readings must be taken on separate days ie ≥ 7.0 mmol/L fasting, ≥ 11.1 mmol/L random
What are diagnosis criteria of Gestational Diabetes?
NICE
- Fasting Glucose = ≥5.6
- Two Hour Glucose = ≥7.8
SIGN
- Fasting Glucose = ≥5.1
- One Hour Glucose = ≥10
- Two Hour Glucose = ≥8.5
What is HbA1c?
- Product of non-enzymatic addition of glucose residue to beta chain to haemaglobin
- Can be measure in a lab and used in diagnosis
- HbA1c is a long term measure of glycaemic control in patients with DM
- Should NOT be used in diagnosing patient suspected of having Type 1 DM
How is Glycated haemoglobin formed?
- Glucose in blood taken up by RBC
- Non-enzymatic condensation reaction of glucose to N-terminal valine residues of β Chain
- Reaction is irreversible
- % glycosylated haemoglobin depends on mean glucose level over the lifespan of a red blood cell (~ 120 days)
Why do we measure HbA1c?
- DCCT & UKPDS showed that HbA1c is the best long-term marker of diabetes control
- Better control of HbA1c leads to better outcomes in people with diabetes
