Glucose monitoring is a critical tool in diabetes management. Diabetes educators rely on glucose data to help patients with self-management and medication decisions.This page focuses on blood glucose meters. Rapidly changing technology is helping to provide more data than ever before.For information on interstitial glucose monitoring please view the glucose sensors page.
- Should we suggest glucose monitoring?
- Glucose monitoring basics
- Frequency of glucose monitoring
- Blood Glucose Meters
- Continuous Glucose Monitoring (Glucose Sensors)
- Pattern Analysis - not yet developed
1. Should we suggest glucose monitoring?
- Studies have not shown self monitoring of blood glucose (SMBG) as a major contributer to lower A1c levels in individuals on diabetes medications other than insulin. However, SMBG may provide benefits related to safety, self-efficacy and quality of life. SMBG is an essential tool in those on insulin as results guide dosing changes.
- Glucose monitoring can be costly. See the psychosocial page for possible financial resources and glucose meters for brands with less costly test strips.
- Benefits of glucose monitoring may include:
- provides patients information for daily insulin dosing decisions
- provides feedback on lifestyle behaviours (food, exercise)
- provides feedback regarding recent medication changes
- provides for a means to verify safe blood glucose levels for driving and taking secretagogues or insulin
- provides patients a means to periodically assess diabetes rather than waiting for an A1c result
2. Blood Glucose Monitoring Basics
All "blood glucose" (BG) meters require a lancet to obtain a small drop of capillary blood from a finger or alternate site (if approved for the brand). A test strip is placed into a BG machine and the blood is placed on the strip. The machine reads the glucose in thte blood and provides a reading in less than a minute.
- Pharmacies in Alberta are responsible for training patients on meters sold in their stores. Patients may need to make an appointment with pharmacy staff.
- All BG meters contain paper training instructions. Many companies also offer videos.
- Educators at Primary Care Networks (family doctors' offices) or diabete centre staff may also train depending on availablity of time. Pharmacy training is heavily relied upon.
- Clean hands: Patients have overdelivered insulin based on incorrect blood glucose readings from unwashed hands.
- Warm hands: It is easier to obtain a sample of blood with warm hands
- Fingers: The finger pad is the standard site for poking, while avoiding the centre where more nerve endings can make testing painful.
- Alternite sites: The forearm, earlobe or the palm by the fatty part of the base of the thumb may be approved for use with some meters; these sites are less accurate if blood glucose is changing quickly.
- Depth: Start with lowest depth and work up if inadquate sample. Many people have lancet depths deeper than required with results in more painful pokes.
- Re-use: Encourage new lancets at least daily, primarily to reduce discomfort and the risk of infection. Advise to never share lancet devices.
- Sharps disposal: Encourage the purchase and use of sharps containers from pharmacies. The cost is small and many pharmacies replace for free if the paitent returns a full container. Sharps may not be disposed of loosely in normal household garbage; fines may be imposed. If not wishing to use sharps containers and pharmacies, patients can visit city/town websites to learn of safe sharps disposal guidelines.
- Paper logbooks or sheets
- Meter software as provided by manufacturers
- Diasend uploads for online storage and viewing of data in reports.
3. Accuracy of Blood Glucose Meters
- Diabetes Centre Calgary uses these parameters below summarized from the 2013 ISO:
- A lab meter difference < 15 % is considered acceptable for lab glucose values > 5.5 mmol/L
- At lab glucose levels < 5.5 mmol/L, a 0.83 mmol/L difference between lab and meter values is considered acceptable. A repeat lab/meter comparison may be ordered at the discretion of the attending physician if the comparison is within this parameter but tighter correlation is desired.
- Please be aware that the DCC guidelines differ from those of Diabetes Canada which suggests a lab meter difference < 15 % is considered acceptable for lab glucose values > 4.2 mmol/L
- Lab meter comparison calculation: (lab glucose - meter glucose) / lab glucose x 100
- Lab meter comparisons are ideally performed using a fasting blood glucose at least once a year.
- Use the Diabetes Canada tool to help decide testing frequency and possible patterns.
- Until continuous glucose monitoring use is widespread, we still need to give thought as to how often we are encourage clients to check their blood sugar levels.
- Think "quality" versus "quantity."
- Consider how much data is needed to make management decisions and to keep this client safe. The required frequency is often less than the client thinks.
- Many diabetes medications do not cause hypoglcyemia and do not impact readings at one specific time of the day. As such, frequent SMBG may not be needed. If an A1c remains out of target and/or recent SMBG results (even limited frequency) clearly indicate the client is not in target, a dose adjustment may be considered.
2 hr After Meal (post prandial or pc) Testing:When considering 'quality' data, the diabetes educator may question if a client needs after meal (pc) blood glucose readings. Blood glucose testing after meals can be challenging, expensive and frustrating. Educators are encouraged to suggest this data only when needed. The following are times when 2 hour pc meals tests may be useful:
- on a medication that addresses pc readings such as repaglinide (Gluconorm) or rapid insulin and fine-tuning an A1c close to target (eg. A1c < 8%)
- before meal readings are in target but A1c is not
- fine-tuning insulin to carbohydrate ratios
- symptoms of hyperglycemia or hypoglycemia pc meals
- determining if high supper readings are due to basal insulin 'running out' or due to lunch bolus (more with type 1 diabetes than type 2 diabetes)
- client curiosity about certain foods or meals
- when pregnant with type 1, type 2 or gestational diabetes