[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Nursing](https://durgical.com/en/nursing/) › [Vital signs and assessment](https://durgical.com/en/nursing/areas/vitals/) › Capillary blood glucose testing # Capillary blood glucose testing - Procedure A fingerstick test measures glucose in a drop of blood from the side of a finger, with a single-use lancet and a clean meter. Updated Nov 5, 2026 ## Key points - Single-use lancet, discarded in the sharps container at the point of use; a pen-like fingerstick device is for one patient only. - A shared meter is cleaned and disinfected after every use per the manufacturer; if there are no cleaning instructions, it is not shared. - Prick the side of the pad of the middle or ring finger; avoid the thumb and index finger (calluses) and the little finger (thin tissue). - Let the alcohol dry, wipe away the first drop and do not squeeze the finger: all of these change the result. - Hypoglycaemia: below 70 milligrams per decilitre; severe: below 54. ## What it is Capillary blood glucose testing measures blood glucose in seconds from a drop obtained by pricking a finger. It is often done before meals and before giving insulin or other diabetes medicines, and when there are symptoms of hypoglycaemia. Its accuracy depends on technique: clean, dry skin, a puncture at the right site, no squeezing and wiping away the first drop. Its safety depends on infection control: lancets and fingerstick devices are never shared, and the meter is cleaned between patients. ## Indications - As ordered: often before meals and before giving insulin or other diabetes medicines. - Symptoms of hypoglycaemia: sweating, shaking, palpitations, hunger, dizziness, irritability or confusion. - Patients on enteral or parenteral nutrition, or on medicines that change glucose, as ordered. - A follow-up check after treating hypoglycaemia, per protocol. ## Contraindications and precautions - Do not prick a swollen, injured, infected or scarred finger, or the same site twice. - Do not use the arm with a fistula or the hand with the IV if another option exists. - Never reuse a lancet or share a fingerstick device: hepatitis B outbreaks have been traced to this. - Check that the strips match the meter, are in date and are stored sealed, away from moisture and heat. - A result that does not fit the patient's condition is repeated and, per protocol, confirmed with a venous sample. ## Equipment - A meter assigned to the patient, or one that has been cleaned and disinfected, with quality control up to date. - Compatible, in-date test strips. - Sterile single-use lancet, preferably with a safety mechanism. - Alcohol swab, dry gauze and gloves. - Sharps container within reach. ## Step by step (and why) - Check the order and identify the patient with two identifiers — the result may change the insulin dose. - Clean your hands, explain the procedure and put on gloves — this protects the patient and you from blood. - Prepare the meter and a compatible, in-date strip — a wrong or expired strip gives false values. - Have the patient's hand washed and dried (with warm water if cold) and choose the side of the middle or ring finger — clean, warm skin bleeds better. - Clean with alcohol and let it air-dry — wet alcohol dilutes the drop and stings. - Prick with one quick, firm movement — one puncture is enough and blood flows well. - Wipe away the first drop and use the next, without squeezing hard — the first and squeezed drops carry tissue fluid. - Touch the strip to the drop, then press the site with gauze — this fills the strip and stops the bleeding. - Discard the lancet in the sharps container and clean the meter — this prevents needlesticks and cross-infection. - Record the value, the time and its relation to meals, and act on the order — without context treatment cannot be adjusted. ## Complications - Pain and bruising at the puncture site. - Local infection from non-aseptic technique or reusing the site. - Scarring and loss of sensation with repeated punctures of the same finger. - Skin damage from adhesive strips in older adults and children. - Transmission of hepatitis B or other infections when lancets or fingerstick devices are shared. ## Next step: when to call for help - If the value is below 70 milligrams per decilitre, apply the facility hypoglycaemia protocol, report it and repeat the check as directed. - Call at once if the value is below 54, if the patient is confused, drowsy or seizing, or cannot swallow. - Call if the value is above the threshold in the order or protocol, or if there are symptoms of hyperglycaemia. - Call if the result does not fit the patient's condition, or if the site keeps bleeding after several minutes of pressure. ## Test yourself Think of the answer, then tap the question to see it. ## Why is the first drop of blood wiped away in a fingerstick test? Because it may be contaminated with tissue fluid or skin debris and change the result. ## Where on the finger is the puncture made, and on which fingers? On the side of the pad of the middle or ring finger; the thumb and index finger are avoided for calluses and the little finger for its thin tissue. ## Why is the finger not squeezed hard? Because it dilutes the sample with tissue fluid and promotes haemolysis, which gives an unreliable result. ## Which infection-control rules apply to the meter and the lancet? The lancet is single-use and the fingerstick device is for one patient only; a shared meter is cleaned and disinfected after every use. ## What capillary glucose value is considered hypoglycaemia? Below 70 milligrams per decilitre; below 54 is severe hypoglycaemia. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/nursing/capillary-blood-glucose-testing/) ## Connections ## Related 1 - [High-alert medications](https://durgical.com/en/nursing/high-alert-medications/) [← All of nursing](https://durgical.com/en/nursing/) Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order. Sources: [WHO guidelines on drawing blood: best practices in phlebotomy (chapter 7, Capillary sampling)](https://www.who.int/publications/i/item/9789241599221) (World Health Organization, 2010); [Considerations for Blood Glucose Monitoring and Insulin Administration](https://www.cdc.gov/injection-safety/hcp/infection-control/index.html) (Centers for Disease Control and Prevention, 2024); [Low Blood Sugar (Hypoglycemia)](https://www.cdc.gov/diabetes/about/low-blood-sugar-hypoglycemia.html) (Centers for Disease Control and Prevention, 2024); [Monitoring Your Blood Sugar](https://www.cdc.gov/diabetes/diabetes-testing/monitoring-blood-sugar.html) (Centers for Disease Control and Prevention, 2024). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. 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