A lancet is a small sharp needle that goes into a lancet device. Patients use it to poke their fingertips to get blood samples and self-monitor blood glucose. “Self-monitoring of blood glucose (SMBG) can be a useful tool in the management of diabetes mellitus. Patients with diabetes often measure their blood glucose to detect hypoglycemia and to adjust insulin dose as needed. Others utilize SMBG to help establish a profile of blood glucose levels and response to nutrition and pharmacotherapy.”1
As a consequence, lancet devices have become essential for diabetes care. “Millions of people with diabetes lance their fingers many times daily as a starting point for performing self-monitoring of blood glucose (SMBG). Current recommendations suggest that all individuals with type 1 diabetes measure at least 3-4 times/day. For other types with diabetes (e.g., insulin-treated people with type 2 diabetes), differing approaches are recommended, while for individuals with type 2 diabetes and no insulin treatment, recommendations for SMBG are very controversial (i.e., ranging from recommendations for frequent testing to no SMBG testing at all) […]
Unfortunately, the process of frequent blood sampling is inconvenient, fairly painful, potentially costly, and presents long-term issues for finger sensitivity. These issues are major reasons why patients are reluctant to perform SMBG frequently and are often noncompliant with therapy guidelines. Reduced BG measurement frequency is highly correlated with suboptimal metabolic control [i.e., high levels of glycated hemoglobin (A1C)], which, in turn, is closely associated with the development of diabetes-related complications. Therefore, any reduction of barriers to performing SMBG is highly relevant for patients to help them avoid serious complications of diabetes and is as important to health insurance providers who are concerned about the enormous costs associated with the treatment of these complications”2 Appropriate use of a lancet and lancing device might reduce the barriers to performing SMBG more often.
The invention of Glucose Meters
“It is over 40 years since Anton Clemens at the Ames Research Division, Miles Laboratories, in Elkhart, Indiana, USA, developed the first blood glucose meter. It combined dry chemistry test strips (Dextrostix) with reflectance photometry to measure blood glucose. The concept of dry chemistry would be elegantly developed later for the analysis of other analytes. Consequently, the first blood glucose meters represent an important landmark technology, which influenced the extensive growth of point of-care (POC) testing in the mid-1980s. Great progress has been achieved in the development of blood glucose meters and this continues to be an active field of study and research.”4
How do Lancets and Lancing Devices work
A lancing device includes a spring to hold the lancet steady and activate the mechanism to puncture the skin carefully. Users can adjust the gauge and set the depth of the incision by selecting the desired measurement. After pricking the fingertip, the spring returns to its initial position. If they choose higher numbers, the incision will be larger. Instead, if they choose a lower number, the incision will be smaller.
Usually, lancing devices have a maximum of five configurations. Specialists advise selecting the third one located in the center. When setting the device on the superficial scope, the user might need to apply more strain and effort to make the lancet prick the finger. Once this happens, it is a sign that the lancing device needs replacing.
Lancing devices help decrease pain and uneasiness while taking a blood sample. Those with higher gauges are the preferred choice as they cause minimal pain or no pain at all. However, selecting an inappropriate measurement may result in multiple punctures, and hence cause more pain. If that is the case, select a different lancet size.
Consider that obtaining an abundant blood sample may be difficult at first, so it could take various attempts to get the desired amount. Specialists recommend washing the hands with warm soapy water and performing a small hand exercise to stimulate blood circulation and more abundant bleeding. This exercise consists of shaking the hand before attempting to prick the finger again.
“Obtaining a blood sample of sufficient volume to perform a successful BG measurement requires the lancet to cut through the upper skin layers to a depth that opens a sufficient number of small blood vessels. The capillary and/or venous blood pressure will then drive the blood outward through the wound channel. However, this spontaneous blood flow will occur only if the local blood pressure is sufficient to force the wound channel open.”5
Patient Instruction by Certified Diabetes Educators
Using a lancet or a lancing device for the first time is a challenging experience for the patient and/or the caregiver, so they need proper instruction. “Clearly, of key importance for patients is how well they were instructed to perform lancing on a day-to-day basis. Most often, such instructions were performed preferably by certified diabetes educators (CDEs) and not by the treating physician. Training provided by the CDE should not be underestimated; this training is an excellent opportunity to optimize the lancing process with the currently available products. The CDE can identify and train patients to use the best lancet device for their individual needs by assessing dexterity, cognition, learning style, coordination, skin type/sensitivities, and visual acuity. In addition, patients tend to be less timid in asking for clarifications from a CDE versus the physician. The following aspects should be addressed by the CDE during training:
- Evaluation and collaborative decision making of lancet and assistive lancing device;
- Device function, including assessment of penetration required; and
Clearly, patients should not only be instructed but also supervised while practicing lancing to learn about:
- Skin preparation,
- Site selection,
- Tips to obtain an adequate blood sample,
- Tips to reduce discomfort, and
- Alternative sites—when and how.
Patients should receive written instruction for reinforcement, and there should always be a follow-up patient visit to assess the lancing technique as well as any potential difficulties.”6
Strip and Meter Handling for Self-Monitoring of Blood Glucose
- “Meter and test strips should be handled with clean, dry hands.
- Test strips are for single-use and unique for each meter. Test strips must be kept in the original canister, as any moisture can affect the integrity of the strip, and the containers should be kept closed. Check for expiration date.
- Strips can be tested for accuracy with the control solution provided initially with each meter and should be checked for the expiration date. The control glucose range for the strips appears on the canister.
- Some meters require coding with each canister. Many of the newer meters do not require coding.
- The amount of blood required is usually very small. Many meters easily pull the blood drop into the end of the strip. An inadequate sample can be a source of error.
- Keep meter and supplies in a cool, dry area, not in the car or in sunlight.
- Bring meter into office visits with diabetes educator or primary care provider to test the accuracy comparatively.”7
Lancing Procedure for Self-Monitoring of Blood Glucose
- “Site preparation: Clean area with warm, soapy water and dry. Food residue can be a source of false high blood sugar values.
- Lancet devices to obtain blood can vary and all use a lancet to prick the skin. Thin, sharp lancets are more comfortable. Lancets should not be reused or cleaned, as they quickly become dull.
- Depth setting on the lancet device controls the penetration of the stick and can be adjusted for best comfort and size of the blood sample. Most meters require very small samples—less than a small teardrop.
- Lancet should be applied firmly to the clean, dry finger, but not with force.
- Sides of the finger should be used, as there is less pain. Use of the third, fourth, and fifth digits may be preferable to spare index finger and thumb.
- Alternate test sites (upper arms and thighs) are approved for many meters. Fingertips or the outer palm are preferred and are more accurate.
- Obtainment of blood samples should be a gentle “milking” from the base of the finger to the lanced tip. Pressure directly on the site of lancing is not recommended.
- Disposal of lancets and SMBG testing supplies should be done according to local laws for sharps. In many locations, a hard plastic container with a screw-top can be disposed of in the household trash.”8
Lancing Procedure by Caregivers
- “Prepare the finger to be lanced by having the patient wash hands in warm water and soap. Dry thoroughly. For convenience, an alcohol wipe may be used to cleanse the finger. Alcohol must dry thoroughly before the finger is lanced.
- Don disposable gloves.
- Turn on the glucose meter. Prepare the meter by validating the proper calibration with the strips to be used. (This usually involves matching a code number on the strip bottle to the code registered on the meter.)
- The meter will indicate its readiness for testing blood glucose by message or symbol. Some meters require that the glucose test strip be inserted at the time.
- Prick the patient’s finger lateral to the fingertip using a lancet/lancing device, obtaining a drop of blood large enough to satisfy the requirements of the testing strips being used. Almost all glucose meters available today require very small amounts, ranging from 0.3 microliters to 4 microliters.
- Apply the blood carefully to the strip test areas (varies by glucose meter model).”9
Lancets are single-use and designed for later disposal; reusing them may lead to health complications and infections. Also, due to its thin structure, the needle deteriorates easily when puncturing the skin, becoming ineffective and injuring the skin if recycled.
Managing difficulties while using a lancet and lancing device
“One practical issue of lancing devices is that changing the actual lancet in the lancing device (i.e., the disposable part) requires a certain amount of visual and mechanical capability with many systems. This can be an issue for many elderly patients. For such patients, easy handling of the finger pricking procedure is essential. The systems on the market differ in this respect considerably; however, again, this has not been studied extensively. Novel devices coming to the market declare that their innovative technology greatly reduces the pain associated with finger pricking and that they are easy to handle at the same time.”10
What are the factors influencing lancing pain with respect to the lancing device?
- “Lancet penetration depth: Lancing pain is closely related to lancet penetration depth. Smaller lancet penetration depth causes less injury to the tissue and therefore less lancing pain. Most lancing devices have an adjustable lancet penetration depth to adapt to individual differences in epidermis thickness.
- Lancet speed: The mechanical pain receptors of the tissue are activated by tissue movement. Higher lancet speed minimizes tissue movement and therefore minimizes lancing pain.
- Lancet shape: Lancets or ‘lanceolates’ are manufactured by grinding facets into the tip of a metal rod, forming a pointed tip and three surfaces with two cutting edges. A very sharp front end of the lancet facilitates tissue penetration.
- Lancet surface: A smooth lancet surface avoids friction of the tissue, further reducing lancing pain.
- Lancet movement: In order to avoid painful vibrations or jolts of the lancet in the tissue, state-of-the-art lancing devices use a combination of rail-guided and cam-driven lancets, enabling a smooth lancet movement.
- Skin fixation: The interface of the lancing device and the patient skin determines the quality of skin fixation during lancing. Better skin fixation means less lancing pain.”11
“Pricking the fingertip several times per day for many years/decades is not only annoying to the patient but also has certain consequences: (1) development of massive scarring/callous formation and (2) loss of sensibility/ perception hindrance. The pain associated with finger pricking is most probably the main reason (besides the costs) why patients refrain from SMBG. In turn, such a reduced measurement frequency has a negative impact on metabolic control. The pain might also induce a negative perception against diabetes and its therapy in general. Keep in mind how difficult it is to convince children to measure BG levels several times a day. This induces a lot of trouble in families with diabetic children.”12
Conveniently for patients and their families, appropriate use of a lancet and a lancing device makes finger pricking a less annoying experience, induces more frequent measurements, and thus, causes a positive impact on metabolic control for diabetic patients.
(1, 7, 8) Self-Monitoring of Blood Glucose: Practical Aspects. Kirk, J.K. & Stegner, J. Journal of Diabetes Science and Technology. 2010. https://journals.sagepub.com/doi/pdf/10.1177/193229681000400225
(2, 3, 5, 6) Lancing: Quo Vadis?. Heinemann, L. & Boecker, D. Journal of Diabetes Science and Technology. 2011. https://journals.sagepub.com/doi/pdf/10.1177/193229681100500420
(4) A history of blood glucose meters and their role in self-monitoring of diabetes mellitus. Clarke, S.F., & Foster, J.R. British Journal Of Biomedical Science. 2012. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.468.2196&rep=rep1&type=pdf
(9) Lippincott manual of nursing practice. Lippincott Williams & Wilkins. Nettina, S. M., Msn, A. B., & Nettina, S. M. (2013). https://books.google.com/books?hl=es&lr=&id=yW8DhPxxUR0C&oi=fnd&pg=PR1&dq=Lippincott+Manual+of+Nursing+Practice+Por+Sandra+M+Nettina,+Msn,+Anp-BC,+Sandra+M.+Nettina&ots=9O9XviKeBw&sig=r7SXbUu7-XjKiMP-nyOxAvwyrhI
(10, 12) Finger Pricking and Pain: A Never Ending Story. Heinemann, L. Journal of Diabetes Science and Technology. 2008. https://journals.sagepub.com/doi/pdf/10.1177/193229680800200526
(11) Comparison of lancing devices for self-monitoring of blood glucose regarding lancing pain. Kocher, S., Tshiananga, J. T., & Koubek, R. 2009. Journal of diabetes science and technology, 3(5), 1136-1143. https://journals.sagepub.com/doi/10.1177/193229680900300517