Diabetes Testing Flashcards
What tests your plasma glucose?
3
- Fasting plasma glucose (FPG)
- Random plasma glucose (RPG)
- Two-hour plasma glucose during an oral glucose tolerance test (2-h OGTT)
What is the normal FPG?
Increased risk for Diabetes “Pre-diabetes”:
Impaired fasting glucose?
Impaired glucose tolerance?
Diabetes Mellitus: Hem A1C ? FPG ? 2h OGTT ? Symptomatic hyperglycemia RPG ?
Normal: FPG is less than 100mg/dL
Impaired fasting glucose (IFG): 100-125
Impaired glucose tolerance (IGT): 2h OGTT of 140-199
Diabetes Mellitus: Hem A1C ≥ 6.5% FPG ≥ 126 2h OGTT ≥ 200 Symptomatic hyperglycemia RPG ≥ 200
**Critical Note: Diagnosis must be confirmed on a subsequent day by measuring any one of the criteria
What is the sensitivity and specificity of the 126 level if using the 2h OGTT ≥ 200 as the reference standard?
Specificity > 95 percent (the ability to rule it in)
Sensitivity about 50% (the ability to rule it out)
In other words, a person that has an FPG of 126 or higher highly likely has diabetes, but a person with a level of, let’s say 120, may still have diabetes when using the 2h OGTT criteria as a reference
Factors that affect blood sugar?
3
Medications
Emotional stress
Physical stress
_____released during stress increase blood sugar.
What kind of stress? 5
Hormones
Physical or emotional stress
- Surgery
- Infection
- Stroke
- MI
- Emotional stress and anxiety
What can elevate blood sugar other than diabetes, IFG, or IGT?
8
- Medications
- Stress hyperglycemia
- Cushing’s syndrome,
- acromegaly,
- pheochromocytoma,
- glucagonoma,
- liver disease,
- pancreatitis
What meds can elevate blood sugar?
4
Steroids
Beta-blockers
Nicotinic acid
Estrogens
Recommendations For Diabetes Screening?
3
- FPG screening every 3 years beginning at age 45 years
- Consider screening at an earlier age (or more frequently if >45yo) if diabetes risk factors are present
- BMI ≥ 25 + 1 or more risk factors
What are the screening tests?
If tests are normal then when should you retest?
- A1C,
- fasting plasma glucose,
- 2 h oral glucose tolerance test
If the tests are normal do it again in three years
DM Risk factors - review
14
- Age ≥ 45
- BMI ≥ 25
- FmHx of DM in a 1st degree relative
- Hx of gestational DM
- High risk ethnicity (African 6. American, Hispanic, Native American, Asian American, Pacific Islanders)
- Hypertension
- HDL less than 35
- Triglycerides ≥ 250
- A1C ≥ 5.7
- Polycystic ovarian syndrome
- Vascular disease
- Sedentary lifestyle
- IFG/IGT
For the diagnosis of diabetes ______ are necessary.
What is not recommended? 2
plasma samples
- Point of care testing for A1C is not recommended for diagnosis
- Finger stick blood glucose is not used for diagnosis
Why do we not use fingerstick for diagnosis?
2
- Venous glucose levels may be higher than capillary levels
For fasting samples and random testing (FPG) - Venous glucose levels lower than capillary
2 h after oral glucose load
AT what levels for FPG do we diagnose as DM?
ANything lower than this value we treat as what?
126 or over.
Anything lower than that and we treat it as impaired fasting glucose
(need two tests)
At what level for random glucose testing do we diagnose diabetes?
What do we follow it up with before we determine the diagnosis?
over 200
FPG
(If the RPG is 200 but FPG is less than 126 then we still treat as IFG)
The _______ is a way to measure the mean glucose level over 3 months. How does it do this? 3
hemoglobin A1C
- Hemoglobin that is formed in new red blood cells enters the circulation without any glucose attached
- Red cells are freely permeable to glucose
- Glucose becomes irreversibly attached to hemoglobin at a rate dependent upon the prevailing blood glucose
(What percent of your red blood cells are coated in sugar)
Hemoglobin A1C correlates best with mean blood glucose over what period of time?
Correlates best with mean blood glucose over the previous 8 to 12 weeks.
Hemoglobin A1C
sources of error?
2
- red blood cell turnover is low (delayed) = flasely high A1Cs
- rapid red cell turnover leads to a greater proportion of younger red cells and falsely low A1C values.
Factors that may alter A1C results:
Increase? 6
Decrease? 4
Increase:
- Iron deficiency anemia
- Alcohol toxicity
- Lead toxicity
- Late pregnancy due to the iron deficiency anemia
- Genetic variants
- Hgb S, Hgb C traits
Decrease:
- Hemolytic anemia
- Chronic blood loss
- Pregnancy
- Chronic renal failure
Routine hemoglobin A1C testing?
2
- At least twice yearly if meeting DM treatment goals
2. Test q 3months if previous medication change or not meeting treatment goals
Fructosamine shows the average of blood glucose control over what period of time?
1-2 weeks of average blood glucose control
Why would you measure Fructosamine?
3
- Pregnant
- Blood loss/hemolytic anemia
- sickle cell
(in these pts the hemoglobin A1C will be falsely high or low)
Abnormal levels of what would cause irregularities in fructosamine?
You would see falsely low levels of it with what?
Albumin
Falsely low levels with rapid albumin turnover
What are we looking for in the urine?
3
Glucose
Ketones
Protein
Glucose in blood is normally filtered at the glomerulus with almost complete reabsorption taking place where?
taking place in the proximal tubule
Glucose in the urine signifies what?
At what levels does glucose in the urine usually occur?
that the filtered load is exceeding the absorptive capability of the proximal tubule
over 180
27
27`
What does glucosuria lead to?
What should we do if this occurs?
Osmotic diuresis
Check a blood sugar
Where are ketones produced?
They are part of what kind of metabolism?
Why do ketone levels increase?
Is it more common in type 1 or 2 and why?
Produced in the liver
Part of fatty acid metabolism
Increase when not enough insulin to use glucose for energy
It occurs when the body cannot use sugar (glucose) as a fuel source because there is no insulin or not enough insulin. (no insulin in type one)
What are the three types of ketones?
Why does positive test for ketones mean excessive amounts??
- Beta-hydroxybutrate (in DKA most are in this form)
- Acetoacetate
- Acetic Acid
There are normally small amounts of ketones present in the serum and urine (which are not detected by conventional testing)
–so you get a positive there has to be a lot!!!!!
In the patient with DKA, urine may be negative for ketones if _____ exists?
The test reacts strongly to what kind of ketone and not strongly with which ketone?
if severe renal insufficiency (kidneys may be unable to filter ketones)
Test reacts strongly to acetoacetic acid but not with beta-hydroxybutyrate. In DKA, most of the ketones present are in the form of beta-hydroxybutyrate
**Negative or weakly positive urine ketone should not sway clinician from possibility of ketoacidosis if presentation is suggestive
Where else might you see ketoacidosis?
3
starvation
vomitting
low carb diets
When to test ketones?
3
Pregnancy
Elevated blood sugars > 300
When suspicious for DKA
Ketones will be detectable in the urine with the following?
8
- Poorly controlled DM
- DKA
- Starvation
- Strict Atkins* diet
- Poisoning
- Certain types of anesthesia
- Alkalosis
- Some metabolic disorders
Ketonuria: False positive tests
4
Levodopa
Phenazopyrine
Valproic acid
Vit C
Albuminuria: To show up on a regular urine dipstick as + for protein, levels need to be
where?
≥300 mg
Screening for albuminuria
3 times
5 years after the diagnosis of Type 1
Upon diagnosis of Type 2
Then annually for all diabetics
Albumin to Creatinine Ratio (ACR) correlates well with what kind of sample?
At what levels do you have microalbumemia?
Correlates well with a 24h urine sample
Microalbuminuria = 30-300 mg albumin/g of creatinine
Diagnosis of diabetic nephropathy?
2
Confirm a positive result with additional tests over the next 3-6 months
2 out of 3 samples that are abnormal within a 6 month period = diabetic nephropathy
Why should patients self monitor their glucose?
3
- To maintain good glucose control
- Allows adjustments of insulin and diet content to be made based on immediate feedback of glucose results
- Allows timely intervention for low glucose readings to avert serious hypoglycemic events
Self monitoring blood glucose:
When should patients test?
5
Frequency of testing depends on may factors
- Fasting AM
- Before and after meals
- Before, during and after exercise
- Before bedtime
- Periodically 2-3 AM?
Self monitoring blood glucose.
How often should it be done:
Type 1?
Type 2?
Type I DM – at least three times daily
Type II DM – depends on degree of control and what medications the person is taking
With decreasing or increasing blood sugars is there less accuracy?
With decreasing blood sugars there is less accuracy
Continuous Glucose Monitoring
measures interstitial fluid how? 2
Measures interstitial fluid by:
- Needle sensor inserted subq
- Whole device implanted subq
In general what does continuous glucose monitoring help with?
hypoglycemia episodes
What are the numbers for impaired fasting glucose?
What are the numbers for impaired glucose tolerance?
What is the fasting blood sugar needed for diagnosis of diabetes?
What A1C level diagnoses diabetes and what are the numbers for treatment goals?
100-125
140-199
126 or higher on two sepeatrate occsions
6.5 or higher on two separate occasiosn. 10% or less
If you get an abnormal plasma glucose or A1C what now?
What random blood glucose constitutes diabetes?
What are some commonly used medications that affect serum glucose?
4
Get a FPG
greater than 200 with symptoms
- steriods,
- beta blocker,
- nicatinic acid and
- estrogens.
