Self-monitoring of blood glucose (SMBG) is an important part of the management of diabetes. Glucose results from home testing sent to a medical care provider impowers the patient to adjust insulin doses under medical supervision to improve glucose control. Also, this data enables the medical care provider to modify insulin and other diabetic medications between clinic visits in order to achieve treatment goals. SMBG can be performed with a meter that measures glucose in a drop of blood from a fingerstick (or alternate site like the arm); or with a continuous glucose monitor (CGM), which is an external sensor with a filament that is inserted under the skin.
According to the American Diabetes Association 2021 Standards of Care  for optimizing self-monitoring of blood glucose (SMBG):
SMBG accuracy is dependent on the instrument and user, so it is important to evaluate each patient’s monitoring technique, both initially and at regular intervals thereafter. Optimal use of SMBG requires proper review and interpretation of the data, by both the patient and the provider, to ensure that data are used in an effective and timely manner. In patients with type 1 diabetes, there is a correlation between greater SMBG frequency and lower A1C. Among patients who check their blood glucose at least once daily, many report taking no action when results are high or low. Patients should be taught how to use SMBG data to adjust food intake, exercise, or pharmacologic therapy to achieve specific goals. Some meters now provide advice to the user in real time, when monitoring glucose levels, while others can be used as a part of integrated health platforms.
There are single-meter studies in which benefits have been found with individual meter systems, but few that compare meters in a head-to-head manner. Certain meter system characteristics, such as the use of lancing devices that are less painful (5) and the ability to reapply blood to a strip with an insufficient initial sample, may also be beneficial to patients (6) and may make SMBG less burdensome for patients to perform.
Listed below are the Standard of Care recommendations and quality of evidence:
7.1 Use of technology should be individualized based on a patient’s needs, desires, skill level, and availability of devices. E
7.2 People who are on insulin using self-monitoring of blood glucose should be encouraged to test when appropriate based on their insulin regimen. This may include testing when fasting, prior to meals and snacks, at bedtime, prior to exercise, when low blood glucose is suspected, after treating low blood glucose until they are normoglycemic, and prior to and while performing critical tasks such as driving. B
7.3 Providers should be aware of the differences in accuracy among glucose meters—only U.S. Food and Drug Administration–approved meters with proven accuracy should be used, with unexpired strips, purchased from a pharmacy or licensed distributor. E
7.4 When prescribed as part of a diabetes self-management education and support program, self-monitoring of blood glucose may help to guide treatment decisions and/or self-management for patients taking less frequent insulin injections. B
7.5 Although self-monitoring of blood glucose in patients on noninsulin therapies has not consistently shown clinically significant reductions in A1C, it may be helpful when altering diet, physical activity, and/or medications (particularly medications that can cause hypoglycemia) in conjunction with a treatment adjustment program. E
7.6 When prescribing self-monitoring of blood glucose, ensure that patients receive ongoing instruction and regular evaluation of technique, results, and their ability to use data, including uploading/sharing data (if applicable), from self-monitoring of blood glucose devices to adjust therapy. E
7.7 Health care providers should be aware of medications and other factors, such as high-dose vitamin C and hypoxemia, that can interfere with glucose meter accuracy and provide clinical management as indicated. E
7.8 When prescribing continuous glucose monitoring (CGM) devices, robust diabetes education, training, and support are required for optimal CGM device implementation and ongoing use. People using CGM devices need to have the ability to perform self-monitoring of blood glucose in order to calibrate their monitor and/or verify readings if discordant from their symptoms. B
7.9 When used properly, real-time continuous glucose monitors in conjunction with multiple daily injections and continuous subcutaneous insulin infusion A and other forms of insulin therapy C are a useful tool to lower and/or maintain A1C levels and/or reduce hypoglycemia in adults and youth with diabetes.
7.10 When used properly, intermittently scanned continuous glucose monitors in conjunction with multiple daily injections and continuous subcutaneous insulin infusion B and other forms of insulin therapy C can be useful and may lower A1C levels and/or reduce hypoglycemia in adults and youth with diabetes to replace self-monitoring of blood glucose.
7.11 In patients on multiple daily injections and continuous subcutaneous insulin infusion, real-time continuous glucose monitoring (CGM) devices should be used as close to daily as possible for maximal benefit. A Intermittently scanned CGM devices should be scanned frequently, at a minimum once every 8 h.
7.12 When used as an adjunct to pre- and postprandial self-monitoring of blood glucose, continuous glucose monitoring can help to achieve A1C targets in diabetes and pregnancy. B
7.13 Use of professional continuous glucose monitoring (CGM) and/or intermittent real-time or intermittently scanned CGM can be helpful in identifying and correcting patterns of hyper- and hypoglycemia and improving A1C levels in people with diabetes on noninsulin as well as basal insulin regimens. C
7.14 Skin reactions, either due to irritation or allergy, should be assessed and addressed to aid in successful use of devices. E
7.15 People who have been using continuous glucose monitors should have continued access across third-party payers. E
The FDA has also published information on home glucose testing:
How accurate is this test? The accuracy of this test depends on many factors including:
- the quality of your meter
- the quality of your test strips Always use new test strips that are authorized for sale in the United States. The FDA has issued a safety communication warning about the risks of using previously owned test strips or test strips that are not authorized for sale in the United States
- how well you perform the test. For example, you should wash and dry your hands before testing and closely follow the instructions for operating your meter.
- your hematocrit (the amount of red blood cells in the blood). If you are severely dehydrated or anemic, your test results may be less accurate. Your health care provider can tell you if your hematocrit is low or high, and can discuss with you how it may affect your glucose testing.
- interfering substances (Some substances, such as Vitamin C, Tylenol, and uric acid, may interfere with your glucose testing). Check the instructions for your meter and test strips to find out what substances may affect the testing accuracy.
- altitude, temperature, and humidity (High altitude, low and high temperatures, and humidity can cause unpredictable effects on glucose results). Check the meter manual and test strip package insert for more information. store and handle the meter and strips according to manufacturer’s instructions. It is important to store test strip vials closed.
How do you choose a Glucose Meter? There are many different types of meters available for purchase that differ in several ways, including:
- amount of blood needed for each test
- how easy it is to use
- pain associated with using the product
- testing speed
- overall size
- ability to store test results in memory
- likelihood of interferences
- ability to transmit data to a computer
- cost of the meter
- cost of the test strips used
- doctor’s recommendation
- technical support provided by the manufacturer
- special features such as automatic timing, error codes, large display screen, or spoken instructions or results
The quality of this data depends upon the accuracy of the glucose monitor. The FDA standards for glucoce meters are 95% within +/- 15% across the measuring range 99% within +/- 20% across the measuring range
There is substantial variation in the accuracy of widely used blood glucose monitoring systems. Klonoff et al evaluated the accuracy of 18 personal glucose meters for the Diabetes Technology Society Blood Glucose Monitor System (BGMS) Surveillance Program in 2018, and found that only 6 of 18 glucose meters met quality standards. They concluded:
Self-testing of blood glucose (BG) using a personal blood glucose monitor (BGM) is a cornerstone of diabetes treatment. BGMs are used for 1) measuring BG to determine therapeutic decisions, 2) calibrating continuous glucose monitoring systems, and 3) detection or confirmation of hypoglycemia. To be both safe and of clinical value, BGM systems should measure BG levels accurately. In conclusion, 6 of the 18 best-selling personal BGMs met a protocol-specified accuracy standard similar to current ISO and FDA standards on three of three studies. These same six meters ranked highest according to four other metrics. Since patients depend on their BGMs for day-to-day management, lack of accuracy may put patients at risk for both hypoglycemia and hyperglycemia. We believe that this study points out the varying degrees to which commonly used BGMs do or do not give accurate information. We hope that this study will provide objective and validated information for patients, health care professionals, and payers to make informed product selection. We also hope that this study will provide important information that will lead regulators to consider introducing a mechanism to evaluate postmarket performance of these types of analytical products.
In this study, the Bayer Contour Next was the most accurate of the 18 meters tested. Specifically, 100% of the tests performed by the Contour Next were compliant with test standards (within 15% of reference value if >=100 (5.55 mmol/L) or 15 mg/dL [0.83 mmol/L] of reference value if <=100 mg/dL [5.55 mmol/L]. The coefficient of variation (SD of the % difference = (BGM reading 2 reference value)/(reference value) was 5.4%. Bias (the average difference as a percent of the reference value) was 1.2% below the reference value. 95% limits of agreement (the range that included 95% of values around the reference value) was -11 to +10.
The Bayer Contour Next One glucose meter fascilitates sending the glucose data to a medicalcare provider. It integrates the glucose test result with a smartphone app so that results are automatically synced and logged, and can be reviewed by a patient and/or sent to a medical care provider for analysis.
Other considerations may be important in selecting a glucose meter. The One Touch Lancing Device was reported by diabetic subjects to be “virtually pain free and less painful than using their current lancing systems”. Also, it is useful for the meter to recognize insufficient blood sample and prompt sample re-application to the same test strip. The Contour Next One system was demonstrated to maintain accuracy with re-application.
Diabetic mobile phone apps in combination with self glucose testing appears to improve diabetes care. Hou et al reviewed published data and stated: 
Participants from 14 studies (n = 1,360) were included and quality assessed.Although there may have been clinical diversity, all type 2 diabetes studies reported a reduction in HbA1c. The mean reduction in participants using an app compared with control was 0.49% (95% Cl 0.30, 0.68; I2 = 10%), with a moderate GRADE of evidence. Subgroup analyses indicated that younger patients were more likely to benefit from the use of diabetes apps, and the effect size was enhanced with health care professional feedback. There was inadequate data to describe the effectiveness of apps for type 1 diabetes.
Apps for diabetes have also been evaluated by Chavez et al:
We looked at the highest scoring apps, with respect to all four MARS [Mobile App Rating Scale] sections (engagement, functionality, aesthetics, and information), app subjective score, and diabetes management tasks score, for a total possible score of 31. The top scoring app (Tactio Health: My Connected Health Logbook) scored 28.61 points and integrated all six diabetes management tasks. The second app (ACCU-CHEK 360° Diabetes Mgmt) scored 25.94. Both were in the top percentile for all subscales. In conclusion, self-monitoring of blood glucose can improve diabetes care. It is important that the glucose meter be accurate and testing technique be correct. Glucose data should be sent to a medical care provider for review. Diabetic care apps that are linked to the meter may provide addtional benefit.
Telemedicine has become increasingly popular because of the COVID-19 pandemic, and has been shown to improve diabetes care. In a 2017 systemic review of diabetes including 111 randomized controlled trials and almost 24,000 patients:
telemedicine interventions significantly but modestly reduced A1C from -0.20 to -0.74 percent compared with usual care. In meta-regression analyses, the effect of telemedicine on HbA1C appeared greatest in trials with higher HbA1C concentrations at baseline, in trials where providers used Web portals or text messaging to communicate with patients and in trials where telemedicine facilitated medication adjustment. Telemedicine had no convincing effect on quality of life, mortality or hypoglycemia. .
In conclusion, self-monitoring of blood glucose can improve diabetes care. It is important that the glucose meter be accurate and testing technique be correct. Glucose data should be sent to a medical care provider for review. Diabetic care apps that are linked to the meter may provide addtional benefit.
- American Diabetes Association. 7. Diabetes technology: Standards of Medical Care in Diabetes—2021.
- Investigation of the Accuracy of 18 Marketed Blood GlucoseMonitors. David C. Klonoff,1 Joan Lee Parkes,2Boris P. Kovatchev,3 David Kerr,4Wendy C. Bevier,4 Ronald L. Brazg,5Mark Christiansen,6 Timothy S. Bailey,7James H. Nichols,8 and Michael A. Kohn9. Diabetes Care. 2018 Aug;41(8):1681-1688. doi: 10.2337/dc17-1960. Epub 2018 Jun 13.
- Blood Glucose Monitoring Devices
- Bern Harrison & Daniel Brown (2020) Accuracy of a blood glucose monitoring system that recognizes insufficient sample blood volume and allows application of more blood to the same test strip, Expert Review of Medical Devices, 17:1, 75-82, DOI: 10.1080/17434440.2020.1704253.
- Clinical Evaluation of a New, Lower Pain, One Touch Lancing Device for People With Diabetes: Virtually Pain-Free Testing and Improved Comfort Compared to Current Lancing Systems Mike Grady, PhD, Greg Lamps, MS, MBA, Ashley Shemain, MBA et al. J Diabetes Sci Technol . 2021 Jan;15(1):53-59. doi: 10.1177/1932296819856665. Epub 2019 Jul 17
- Do Mobile Phone ApplicationsImprove Glycemic Control (HbA1c) in the Self-management of Diabetes? A Systematic Review,Meta-analysis, and GRADE of14 Randomized Trials. Can Hou,1 Ben Carter,1,2 Jonathan Hewitt,1Trevor Francisa,1 and Sharon Mayor.
- Mobile Apps for the Management of Diabetes. Chavez S, Fedele D, Guo Y, Bernier A, Smith M, Warnick J, and Modave F.
- Faruque LI, Wiebe N, Ehteshami-Afshar A, et al. CMAJ.Effect of telemedicine on glycated hemoglobin in diabetes: a systematic review and meta-analysis of randomied trials.
Disclaimer: Since healthcare is complicated and personal, you should discuss these topics with your healthcare provider before applying this information to your own health. This website does not intend to diagnose or treat any disease or medical condition. Its only purpose is to assist people to monitor their health at home under the supervision of their healthcare provider.