Can hematocrit levels affect results?

Hematocrit levels can affect results whether the sample is obtained from forearm or from fingerstick. Hematocrit levels less than 30% may cause falsely high readings and hematocrit levels greater than 55% may cause falsely low readings. If the customer does not know their hematocrit level, they should consult their health care professional. Hematocrit levels may be affected by too much squeezing during site preparation.

Can circulation problems affect results?

Yes, circulation problems can affect results whether the sample is obtained from forearm or from fingerstick. Read the Owners' Manual for information on testing precautions and limitations. As stated in the package insert for OneTouch® Ultra® Meters, test results may be falsely low if you are severely dehydrated or severely hypotensive, in shock, or in hyperosmolar state (with or without ketosis). Critically ill patients should not be tested with blood glucose meters.

Can I compare results obtained using a sample from their forearm with a result from a sample obtained using forearm or finger with a different meter?

Assessing meter system accuracy by comparing results from two different meters is not recommended since neither device can be considered a true reference value. It is recommended that comparisons be done directly with a laboratory test and a blood glucose test using a sample from either the finger or the forearm with the meter your patient uses most often.

Is fasting required when comparing a blood glucose lab test result to a blood glucose meter result using an forearm sample?

As when comparing capillary fingertip results to a venous laboratory value, the sample collections should be performed at the same time when the patient is in a fasting state.

When comparing results from the lab and a result using a sample obtained from the forearm on a blood glucose meter, it is best to have had no food in the last 4 hours.

Can certain medications or health conditions affect results from the forearm which are not noticeable when doing fingerstick testing?

Apart from physiological differences in the way different areas of the body respond to meals, insulin or physical activity, we are not aware of any health conditions or medications that would affect forearm results differently than finger results.

Certain conditions such as abnormal hematocrit levels or circulation problems can affect blood glucose results, regardless of the testing site location.

Instruct your patients to obtain finger results in conjunction with forearm results to help assess whether the site to site difference is significant for that individual.

Can sample size affect the result?

Yes, sample size can affect the result. The patient should always follow the instructions in the Owner's Manual for applying blood to the test strip and make sure that the blood sample has completely filled the confirmation window of the OneTouch® Ultra Test Strip.

Which result should be used to determine how much medication to take if there is a difference between an forearm test and a fingerstick test?

If there is a difference between a result using a sample from the forearm and a result from a fingerstick test, advise the patient to use the result from the fingerstick.

What if a patient observes a difference between forearm and fingertip results greater than 20%?

When comparing results using a sample obtained from the forearm and from a fingerstick your patients should be in a fasting or pre-meal state (to have had no food in the last 2-3 hours).

What is the percentage of difference when comparing results from the forearm to a result from a fingerstick test result?

If a patient tests before meals or 2 hours or more after a meal the forearm and finger results should be within 20% of each other.

Why are there differences between forearm and fingertip results?

Glucose concentrations in the body vary due to different rates of glucose utilisation by different body tissues. The varying rates of glucose utilisation may be due to varying amounts of muscle and fat tissue in parts of the body, muscular activity, and variations in blood flow. It is not known which of the sites reflects blood glucose values of greatest physiological significance with regard to managing diabetes.