Diagnosing diabetes and blood glucose interpretation

Question 1

For a Type 2 diabetic which diagnostic tests would be used for assessment?

Answer 1

For a type 2 diabetic with symptoms present, one of the following diagnostic tests need to be administered with a positive test result.
If symptoms are not present then two of the following diagnostic tests must be administered in combination with positive test results for both:
Random venous blood glucose (>11.1 mmol/L)
Fasting venous blood glucose (>7 mmol/L)
Glucose tolerance test (>11.1 mmol/L)
HbA1c (>48 mmol/mol)

Question 2

Explain the rationale of using a glucose tolerance test.

Answer 2

To assess whether the body has difficulty metabolising an intake of sugar/carbohydrates.
It is often used for patients that have borderline glucose levels around the diagnostic threshold.

Question 3

Explain the process of a oral glucose tolerance test.

Answer 3

The patient will have to fast for 8-12 hours before the test. On arrival a fasting venous blood sample will be taken before having 75 grams of anhydrous glucose (often in a powder). Then at regular intervals a blood sample will be taken (every 30 minutes) or just a single blood glucose test at 2 hours after the administration of rapidly absorbing glucose.

Question 4

Which group of patients cannot have confirmation of a diabetic diagnosis confirmed by a HbA1c?

Answer 4

For children for either types of diabetes
For gestational diabetes
For suspected Type 1 diabetes
Those who have had symptoms less than 2 months
Patients who are high risk and are acutely ill
Presence of genetic, haematologic and illness-related factors that influence HbA1c and its measurement
Patients with pancreatic damage
Patient that are taking medication that cause rapid spikes in blood glucose levels such as steroids or anti-psychotics

Question 5

How do HbA1c values differ for a patient without diabetes compare to a patient with diabetes?

Answer 5

A patient without diabetes you would expect their HbA1c value to be approximately 4-6% (about 40mmol/mol) whereas to diagnose a patient with diabetes you would expect over 6.5% (over 48mmol/mol)of their haemoglobin to be glycated.

Question 6

What is the rationale of using a HbA1c test?

Answer 6

It is used to measure a patient’s average blood glucose levels across the lifespan of a hemoglobin molecule (roughly 8-12 weeks).

Question 7

When is a HbA1c test used and why is it useful?

Answer 7

Can be used in the diagnosis of Type 2 and for the monitoring patient’s self-management of blood glucose levels at their three or sixth monthly diabetic review.
They are particularly useful for monitoring a patient’s control of their blood glucose as using a fingerprick test just indicates their control of blood glucose that day whereas the HbA1c value indicates the patient’s control of their blood glucose over the lifespan of a haemoglobin molecule.

Question 8

At what blood glucose levels do symptoms of hyperglycemia and hypoglycaemia appear, and what symptoms would they expect to experience at those levels?

Answer 8

For hyperglycemia symptoms such as increased thirst, urination, unexplained weight loss, tiredness and blurred vision begin to appear when blood glucose levels reach >10-11 mmol/L.
For hypoglycemia symptoms such as disorientation, hyperventilation, reduced consciousness, blurred/ double vision occur when blood glucose levels drop below 3mmol/L.

Question 9

How quickly do symptoms of Type 1 diabetes appear?

Answer 9

In children symptoms of diabetes develop within a few hours but most likely days to a week. In adults with type 1 diabetes usually it takes a bit longer such as over days or weeks.

Question 10

Describe how diabetic ketoacidosis differs from hyperosmolar non-ketonic syndrome?

Answer 10

Diabetic ketoacidosis is a clinical manifestation of Type 1 diabetes (undiagnosed or newly diagnosed) whereas hyperosmolar non-ketonic syndrome is a manifestation of Type 2 diabetes (undiagnosed or newely diagnosed). Whilst the symptoms are very similar (hyperventilation, nausea, vomiting, dehydration, weakeness and reduced consciousness a key difference is that diabetic ketoacidosis has presence of ketone breath (pear sensation).

Question 11

At what blood glucose level does HONK usually appear?

Answer 11

> 33 mmol/L

Question 12

At what blood glucose level does DKA usually appear?

Answer 12

> 11 mmol/L (when they remain dangerously high). Do a ketone test when blood glucose is at this level.

Question 13

Interpret blood ketone test results:

Answer 13

<0.6mmol/L is normal
0.6-1.5mmol/L at slight risk of DKA, retest in 2 hours
1.6-2.9mmol/L at an increased risk of DKA, contact GP or diabetic care team
3mmol/L or above, contact your diabetic care team and get medical help immediately

Question 14

What are the advantages and disadvantages of using a urine test for management of diabetes?

Answer 14

They are beneficial for testing for ketones (indicating diabetic keto acidosis).
However they are not good for diagnosing diabetes as changes in urine concentration of glucose lags significantly to changes in blood glucose. Furthermore each patient has a different threshold for when glucose starts to over spill into the kidney.

Question 15

Explain the five classical symptoms of diabetes?

Answer 15

Polyuria (when blood glucose levels exceed the renal threshold it causes osmotic diuresis)
Polydipsia (increased thirst due to polyuria)
Weight loss (inability of glucose uptake into cells resulting in the body burning fat and muscle)
Fatigue (inability to get blood glucose into cells)
Blurred vision (changes in blood glucose levels alters the refractive index in the eye).

Question 16

What other symptoms are indicators of particularly type 2 diabetes?

Answer 16

Recurrent urinary infections such as UTIs and thrush
Chronic skin infections (elevated blood glucose levels impairs phagocyte function)
Presentation of complications associated with diabetes such as retinopathy, neuropathy, nephropathy

Question 17

What is the normal blood glucose levels for a patient without diabetes?

Answer 17

3.4 - 5.8mmol/L

Question 18

What are the target glucose levels for a patient with diabetes?

Answer 18

Upon waking: 4 - 7 mmol/L
Before eating: 4 - 7 mmol/L
90 minutes after eating: 5 - 9 mmol/L

Question 19

In a patient that does not have diabetes what level does blood glucose rise to after eating?

Answer 19

Between 4-6 mmol/L before meals and less than 8mmol/L 2 hours after eating

Question 20

How often should a Type 1 diabetic or a Type 2 diabetic on insulin therapy monitor their blood glucose?

Answer 20

They should monitor their blood glucose at least four times a day - before each meal and upon waking and/or before going to sleep.
They should also monitor their blood glucose level before driving or before exercise.

Question 21

How often should a Type 2 diabetic only taking oral hypoglycemic medication monitor their blood glucose?

Answer 21

They are not required to monitor their blood glucose and it will only be measured in their 3/6/12 month diabetic check up. However many Type 2 diabetics not on insulin therapy will choose to monitor their blood glucose levels for reassurance.

Question 22

When are the different types of blood glucose monitoring used?

Answer 22

Finger prick tests are for the day to day management of diabetics on insulin therapy.
Venous blood glucose samples are used primarily for diagnostic purposes however they are also used in the diabetic check ups.
Interstitial fluid glucose tests are used in the flash or continuous glucose monitoring

Question 23

What is the purpose of patients on insulin monitoring their blood glucose?

Answer 23

Adjust doses of insulin accordingly to ensure blood glucose levels are within the optimum range therefore,
Avoiding both hyperglycemia and hypoglycemia
Adjust to requirements for exercise
Adjust for driving
Adjust for sickness/illness

Question 24

What is the difference between flash glucose monitors and the continuous glucose monitors?

Answer 24

Whilst both are the same types of sensors with the sensitive needle monitoring blood glucose in the interstitial fluid.
Flash glucose monitors link to a phone and when scanned over by a device they automatically upload results onto an e-reader. With flash glucose monitors you still have to inject insulin accordingly.
Continuous glucose monitors however link directly to an insulin pump so they insulin can be released as according to the level of glucose within the interstitial fluid. This can be calibrated with a finger prick test.

Question 25

Describe the method of taking a blood glucose reading using a finger prick test?

Answer 25

Firstly wash your hands with warm water to ensure no glucose is on the surface of your hands and to increase circulation. Then dry your hands- can rub together or shake to further improve circulation.
Next prepare your blood glucose meter by sticking a new test strip into the device which should turn it on.
Then twist your lancing device to remove the lid and then add a new lancet. Twist the cap off the lancet to expose the needle and then put the cap of the lancing device back on.
Select the puncture depth setting right for you.
Pull the sliding barrel back so it is locked into place, place the device on the side of the finger (not thumb or index finger) and then click the button.
You want a bubble of blood to appear, wipe away the first bubble of blood but the second one should be held up to a vertical test strip in a meter.
Record result in a diary or upload results to an app.
Test strips and lancets should be removed and placed in a sharps bin.

Question 26

When should control solution be used for a blood glucose meter?

Answer 26

New meter
New pack of test strips
If its is giving unexpected results
If it is not working
If it is dropped or damaged

Question 27

What are some of the symptoms of a hypo?

Answer 27

Palpitations
Disorientation
Tremour
Hunger
Sweating
Numbness
Tingling
Blurred vision
Fatigue
Headache

Question 28

What additional symptoms do you usually see in a more severe hypo?

Answer 28

Agitated
Aggressive
Confusion
Drowsy
Reduced consciousness (unconscious)
Seizure
Slurred speech

Question 29

What is recommended if a diabetic patient believes they are experiencing a hypo?

Answer 29

They need 15-20 grams of rapidly absorbing glucose, examples include;
90mL of non-diet coke
1.5-2 tubes of GlucoGel
3 sugar lumps

10-15 minutes later they then need to take a blood glucose test and if the blood glucose has not risen they need to repeat with another 15-20 grams.
Follow with a snack or meal containing a sustained carbohydrate

Question 30

In moderate or severe hypos what else is often used?

Answer 30

If they are still rousable can administer an intramusclar injection of glucagon (1mg) or if they are not rousable then IV glucose (150mL of 10% over 10-15 minutes).

Question 31

What are the causes of a hypo?

Answer 31

Incorrect dosing of basal insulin at night
Delayed or missed meal
Excess alcohol
More exercise than usual
Heat
Stress

Question 32

In patients who have established diabetes, what are some of the causes of DKA?

Answer 32

Raised blood glucose levels caused by being on your period
Having surgery or sustaining an injury
Missed insulin dose
Raised blood glucose levels caused by a growth spurt or puberty
Being ill with a chest infection, flu or UTI
Excessive alcohol

Question 33

What does the treatment for DKA include?

Answer 33

IV insulin
IV fluids and nutrients
Monitoring for any damage to vital organs such as the kidneys, brain and lungs

Question 34

Explain some of the symptoms of DKA.

Answer 34

There is a significant rise in blood glucose levels which causes osmotic diuresis and hence dehydration occurs also due to vomitting resulting in low blood pressure.
There is an increase in ketone bodies resulting in metabolic acidosis, body compensates by increasing respiration resulting in air hunger.
Hyperosmolality (fluid status), dehydration
Low potassium levels due to metabolic processes and polyuria
Muscle catabolism and general weakness

Question 35

Why does hyperosmolar non-ketonic syndrome not involve ketone breath?

Answer 35

There is no significant ketosis and therefore acidosis due to some endogenous insulin levels which are sufficient enough to inhibit hepatic ketogenesis.

Question 36

What are both of the biochemical tests for DKA and HONK?

Answer 36

Urea, creatinine, eGFR
Blood glucose
Electrolytes
Arterial pH, pO2 and pco2

Question 37

What are diagnostic investigations may you make?

Answer 37

Blood pressure (hypertension, CVD)
Urine analysis - protein/albumin (nephropathy)
Renal function (nephropathy)
Liver function (just for drug selection)
Lipids (hyperlipidemia, statin therapy, CVD)