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People living with diabetes should check their blood sugar regularly. There are currently two main options for monitoring glucose levels — continuous glucose monitoring devices and blood glucose meters. The best monitors give reliable, consistent readings to help guide a person’s treatment.

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Please note that the writer of this article has not tried these products. All information presented is purely research-based.

There are two types of glucose monitors:

  • continuous glucose monitor (CGM)
  • blood glucose meter (BGM)

Both types of monitors have different characteristics, benefits, and drawbacks that a person with diabetes should consider.

Both CGM and BGM monitors require a prescription.


CGMs check blood sugar levels automatically at timed intervals. In most cases, they reduce the number of times a person needs to prick their finger to test blood sugar levels during the day.

A CGM sensor requires insertion under the skin, typically of the abdomen, buttocks, thighs, or upper arm. Some models require a person to insert the device themselves, while others may require a visit to the doctor’s office.

A CGM contains three components:

  • sensors
  • transmitters
  • receivers or display units

S The sensors test for the presence of glucose and create an electrical current that transmitters pass along to receivers. The device tests every 5 minutes and either provides real-time data, a regular report, or a combination of both.

Some CGMs require regular calibration using BGMs, while others may need infrequent calibration. A person should follow all instructions from their doctor or healthcare professional and the device manufacturer.

Each part of the unit usually has a separate cost, and both sensors and transmitters need regular replacement. How often a person should replace the strips or transmitters can vary by brand, as can the price.

CGM pros and cons


  • According to a 2020 study, CGMs improved glycemic control in people with types 1 or 2 diabetes.
  • A 2018 study found CGMs can help with assessing periods of extreme fluctuations of blood sugar levels.
  • CGMs prevent periods of extremely low blood sugar levels.
  • CGMs insert under the skin and therefore reduce the need for repeated finger pricks.


  • Most CGMs still need at least two finger pricks per day for calibration.
  • Doctors cannot make a treatment decision based on CGM data alone.
  • CGMs are often more expensive than BGMs.
  • User error, including device installation, can hinder effectiveness.
  • Requires under-skin insertion, which may deter some people.


BGMs are single-use blood tests to check blood glucose levels. It is a manual process in which a person needs to prick their finger, collect a blood sample, and run the test to obtain their current blood sugar level.

BGM pros and cons


  • They provide accurate results.
  • BGMs are often less expensive than CGMs.
  • Added features on some models can provide additional benefits, such as not needing test strips and downloadable results.


  • User error can affect accuracy.
  • They provide limited data.
  • A person needs to do multiple daily finger pricks.

A person who has diabetes may need to check their blood sugar levels several times each day. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), times will vary based on the type of diabetes a person has and the medications they are taking. They note that the most common times to check blood sugar include:

  • when first waking up or after a long fast
  • before a meal
  • 2 hours after a meal
  • before going to sleep

A person should check with their doctor how often they should self-monitor their glucose levels with a BGM.

When using a CGM, the device will typically check blood glucose levels every 5 minutes. A person can often access charts, graphs, and other data related to their results.

Individuals with diabetes will typically monitor glucose levels with either BGMs or a combination of BGMs and CGMs. Some of the following factors may affect a person’s decision to purchase a particular brand or product:

  • Cost: BGMs are generally less expensive than CGMs.
  • Insurance or Medicare coverage: How much of the costs will insurance cover?
  • Ease of use: How easy are the devices to use, including running tests and recording data?
  • Added features: Several devices come with companion software, different display options, and other features a person may find appealing.
  • Third-party testing and US Food and Drug Administration (FDA) approval: Blood glucose monitors are medical devices. They should undergo independent testing and obtain FDA approval.

Below, we look at some of the best CGMs for a person to consider.

Dexcom G6 CGM System

For continual measurement from a below-skin sensor

The Dexcom G6 CGM System is a CGM that provides automatic updates to a connected device.

The transmitters send information to an app that a person can then access via their smartphone, tablet, or computer. It can also work with a specific device transmitter that a person with Medicare coverage needs for reimbursement.

Dexcom sensors last up to 10 days, and the transmitters last up to 90 days. A person must regularly replace both.

The compatible app can send notifications if glucose levels drop too low or spike too high.

Individuals can purchase the Dexcom system at various pharmacies or online.

The Guardian Connect System

For predictive glucose spike warnings

The Guardian Connect System from Medtronic is a CGM that predicts potential spikes in glucose levels and sends warning alerts accordingly. The company offers features such as:

  • a 30-day free trial
  • rechargeable transmitter
  • app for both Android and iOS devices

Medtronic is working with over 600 insurance companies to make the device financially accessible to a broader group of people.

Individuals can register for a 30-day free trial by completing a form on the company’s website.

FreeStyle Libre 2 System

For glucose alarms

The FreeStyle Libre 2 system is another CGM that automatically measures glucose levels.

Some features include:

  • optional glucose alarms
  • 14-day free trial period with guided “how-to” support
  • sensors that last for 14 days

The system currently requires a person to use their compatible device, and the app is not yet FDA approved.

A person with private health insurance could expect to pay up to $60 each month for FreeStyle’s sensors.

Individuals can sign up for a free trial on the company’s website.

Below, we look at some of the best BGMs for a person to consider.

Contour Next One

For tracking and sharing with medical professionals

The Contour Next One is a BGM that uses test strips to provide accurate blood glucose measurements. Some features include:

  • ease of use, with test results within 5 seconds
  • second-chance technology — allowing a person to reuse the same test strip if they did not take enough blood the first time
  • connection to a free Contour Diabetes app for tracking and sharing data with healthcare professionals

The Contour Next One requires a person to use their test strips for accurate results.

The device is available to purchase online.

OneDrop Glucose Meter

For a monthly digital subscription

OneDrop is a BGM that uses a small amount of blood to test blood glucose levels. A person can purchase a kit that includes:

  • an FDA-approved digital meter that has app connectivity via a subscription
  • 25 test strips
  • 10 lancets
  • carrying case
  • lancing device

Individuals signing up for monthly or yearly subscriptions will automatically receive 50 testing strips each month.

A person can sign up for renewing test strips and a digital membership on the company website.

The NIDDK recommends a person follow all instructions provided by their doctor or healthcare professional and the glucose monitor’s manufacturer.

When using a BGM, the Centers for Disease Control and Prevention (CDC) recommends a person follow these safety tips:

  • never share any needles or other portions of the device that come in contact with blood
  • thoroughly wash hands with soap and water before testing
  • clean and check the monitor before use
  • properly dispose of the lancet and strip
  • store test strips at room temperature

Glucose monitors test glucose levels to help a person better manage their type 1 or type 2 diabetes. There are two main types of monitors, CGMs and BGMs.

CGMs provide regular, automatic monitoring of glucose levels, and BGMs require manual blood sugar tests, typically using a finger prick.

Both have some advantages and disadvantages for their use. A person should consult their doctor about the best glucose monitor device to fit their needs and lifestyle.

Please note: Medical News Today does not imply warranty of fitness for a particular purpose or endorse any of these applications. Medical News Today has not evaluated these for medical accuracy. The Food and Drug Administration (FDA) has not approved them unless otherwise indicated.