The Best Blood Glucose Monitors for Managing Diabetes
Diabetes, though incurable, can be effectively managed. There are two very effective ways that you can manage your diabetes.
- One way is through self-monitoring of blood glucose (SMBG) with a personal glucose monitor.
- The other way is with a continuous glucose monitoring(CGM) device.
You can live a normal life with diabetes if you learn to properly manage your diabetes with the right glucose monitoring technique.
A glucose monitor lets you know when your blood glucose level is too high or too low so that you can take the proper actions necessary to regulate your blood glucose level back to normal.
Monitoring your glucose will help you easily know what food or activities affect your glucose level and how effective your medication (if you are taking one to manage your diabetes) is on controlling your glucose level. This information will help you to optimize your lifestyle, exercise regimen, and insulin therapy to ensure your glucose level is under your control.
Here, I provide you a deep-dive on how you can use a blood glucose monitor (glucometers) to manage your diabetes. I also provide you information on
- how a glucose monitor works
- what to look for in a glucose monitor
- how to select an accurate glucose monitor
- Future trends on glucose monitors
About Diabetes
Diabetes is a very common disorder that affects about 10 % of the US population. The percentage is expected to rise as time goes on. Obesity is believed to be responsible for this upward trend in diabetes cases. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769839/pdf/dst-03-0001.pdf)
If diabetes is left unmanaged it can lead to complications that include:
- Skin infections
- Eye Infections (Glaucoma, Cataracts, blindness)
- Foot Ulcers
- Need for foot amputation
- Kidney Failure
- High blood pressure that can lead to heart attack and stroke
https://www.diabetes.org/diabetes/complications
Worldwide, diabetes is one of the leading causes of death. According to the World Health Organization, diabetes is the 7th leading cause of global death in 2016. https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death
However, the good news is that people with diabetes can live a normal healthy life as long as they manage their diabetes properly by:
- Staying on top of their blood glucose level with glucose monitors
- Insulin therapy
- Medication
- Exercise
- Proper Diet
How Diabetes Occurs
Diabetes occurs when your body is having problems converting glucose in your blood to energy in your body cells, starving your body cells of the energy that comes from glucose. When you eat food containing carbs, the carbs are broken down into glucose, a type of sugar.
The types of carbohydrates your body can break down into glucose are:
- Starch foods
- Fruits
- Sugar
- Milk
- Diary Products
Your stomach and small intestines are responsible for releasing glucose into your bloodstream for transportation to your body cells. Also, some of this glucose may be stored in your liver. Your body cells need glucose to make energy.
The pancreas, a gland behind your stomach is responsible for producing the hormone called insulin. Insulin is vital for converting blood glucose into the energy at your body cells for energy.
Whenever your stomach, small intestine, or liver steps up to produce glucose, your pancreas steps up to produce more insulin. This natural feedback mechanism ensures that your blood glucose level is always normal.
When you suffer from diabetes, this optimum feedback loop between the glucose-producing organs (stomach, intestine, liver) and the insulin-producing organ (pancreas) becomes compromised. This will lead to high blood sugar (diabetes).
There are two major types of diabetes:
- Type I Diabetes which is unpreventable
- Type II Diabetes which is preventable
The other types of diabetes that are common in specific populations are:
- Gestational Diabetes
- Drug-Induced Diabetes
Type 1 Diabetes
Type 1 Diabetes account for 10% of all diabetes cases. When you have type 1 diabetes, your pancreas does not produce enough insulin. This means the blood glucose produced by your body cannot be broken down. This means this glucose will linger in your bloodstream because your pancreas has not produced the insulin needed to convert this glucose into energy.
The inability of the pancreas to produce insulin in Type 1 diabetics is due to an autoimmune deficiency that destroys pancreatic cells that produce insulin.
Symptoms of Type I diabetes occur quickly (over a few weeks) when Type I diabetes starts developing. These symptoms include:
- Frequent urination
- Increased thirst
- Tiredness
- Weight loss
- Extreme hunger
- blurred vision
Fortunately, when caught early with proper glucose tests, the symptoms of Type 1 diabetes can be quickly reversed with life-long insulin therapy.
Research has shown proper management Type I diabetes with insulin-therapy improves your quality of life, reduce your chances of developing fatalities due to diabetes, and extend your life. (https://pubmed.ncbi.nlm.nih.gov/8892716/).
Type II Diabetes
Type II diabetes accounts for 90 percent of all diabetes cases. In type II diabetes, your body produces glucose the normal way by breaking down carbohydrates. Your pancreas also produces insulin needed to convert glucose to energy in your body cells.
However, in Type II diabetes, your body may not be producing enough insulin. Also, in some Type II diabetes situation, your body develops insulin resistance. With insulin resistance, your body refuses to use up insulin to produce energy.
One of the reasons your body may be unable to process insulin (insulin resistance) is because of you have excess adipose tissue whereby your fat cells block your body cells from using insulin. However, Type II diabetes may occur in normal-weight people too.
Unlike Type-I diabetes, Type II diabetes can lead to both high blood glucose levels and high insulin levels.
Type II diabetes and Type I diabetes have the same symptoms. However, the symptoms for type II diabetes take a long time (up to 10 years) to develop.
Type II diabetes can be treated with medication, exercise to lose weight, lifestyle changes, diet regimen. In extreme cases, type II diabetes is treated with insulin therapy.
The foods the can help with managing diabetes are:
- fruits and vegetables
- fish
- whole grains and nuts
- legumes
- eggs
https://diatribe.org/what-should-i-eat-diabetes
Gestational Diabetes
This occurs in a pregnant woman in her third semester. This is likely due to pregnancy hormones that cause blood glucose levels to rise.
Drug-Induced Diabetes
Some medication such as steroid medications causes the blood glucose level to rise. The mechanism by which this happens is similar to how insulin resistance causes type II diabetes. https://www.ndss.com.au/about-diabetes/resources/find-a-resource/steroid-medications-and-diabetes-fact-sheet/
Diabetes Diagnosis: Prediabetic and Diabetic Blood Glucose Levels
Diabetes is diagnosed by measuring blood glucose levels. There are four main ways by which glucose levels are measured:
- Fasting Glucose Test
- Non-Fasting Glucose/Random Glucose Test
- Oral Glucose Tolerance Test
- Glycated Haemoglobin (Hb1Ac) Test
The World Health Organization provides recommendation on what glucose levels are diabetic levels for each of these tests (except for the Hb1Ac test) https://www.who.int/diabetes/publications/Definition%20and%20diagnosis%20of%20diabetes_new.pdf
Fasting Glucose Test
In this test, a diabetic patient is allowed no food or drink (except water) for 8 hours, and the glucose level is then measured after this fast.
A blood glucose level of 100 – 125mg/dL (milligram per deciliter of blood) indicates prediabetes while a blood glucose level greater than or equal to 126 mg/dL indicates diabetes.
Non-Fasting Glucose/Random Glucose Test
This test can be taken anytime without the patient fasting. A blood glucose level greater than or equal to 200 mg/dL indicates diabetes.
Oral Glucose Tolerance Test
AFor the oral glucose tolerance test, the patient is given oral glucose, and the patient’s blood glucose level is measured at time intervals. This is done to see how well the patient’s body system can process glucose and regulate the blood glucose level.
A blood glucose level between 140 – 199 mg/dL indicates pre-diabetes, and a blood glucose level greater than or equal to 200 mg/dL indicates diabetes.
Glucose Measurement Conversion from mg/dL to mmol/L
The above blood sugars are specified in units of milligrams per decileter (mg/dL), which is the unit used in the United States of America. In the United Kingdom countries, blood glucose levels are specified in millimole per liter (mmol/L). To convert from mg/dL to mmol/L, divide by 18 the mg/dL value.
Glycated Haemoglobin (Hb1Ac) Test
This test is used to determine the proportion of blood hemoglobin with glucose molecules stuck on them. This proportion does not vary rapidly over time. Therefore, it tells what the glucose level has been historically (up to 3 months ago). An HbA1c level between 5.7% to 6.4% indicates prediabetes, while an HbA1c of 6.5% or higher indicates diabetes.
How often should you check your blood glucose level?
If you are not at risk of getting diabetes, you should check your blood glucose level at least once a year (during your annual physical exams).
If you have been diagnosed with Type I diabetes, you should check your blood glucose level at least 4 times a day.
If you have been diagnosed with Type II diabetes you should check your glucose level at least 2 times a day.
If you have been diagnosed with diabetes, you need a blood glucose monitor to regularly check your blood glucose level to ensure your blood glucose level does not get into an unsafe zone.
Types of Blood Glucose Monitors
There are two broad types of blood glucose monitors that you can use to keep track of your blood glucose levels:
- Self-monitoring of Blood Glucose (SMBG) devices
- Continuous Glucose Monitoring (CGM) devices
Self-Monitoring of Blood Glucose (SMBG) devices
These are the finger-pricking glucose monitors. This type of glucose monitor is the most common type for personalized glucose monitoring. The parts of this glucose monitor are:
- Needle
- Lancet ( a lancing device)
- Glucose Test Strip
- Handheld unit
To use this type of glucose monitor, you prick your finger with a sharp needle attached to a lancet to draw a drop of blood. Then you place the drop of blood on the test strip that is attached to the handheld unit. The handheld unit processes the glucose signal it receives from the glucose strip and then displays the glucose measurement.
How an SMBG Glucose Monitor Works
When you place a blood drop on the glucose monitor strip, a chemical reaction is initiated between glucose in the blood sample and a special enzyme in the glucose strip. This chemical reaction leads to the generation of electric current. The electric current generated is proportional to the amount of glucose in the blood. The handheld unit of the monitor converts this electric current into the corresponding glucose measurement.
Advantages of SMBG Glucose Monitors
- They are generally more accurate compared to the Continous Glucose Monitoring Systems (CGMs). More on CGMs later.
- They are generally cheaper compared to CGMs.
Disadvantages of SMBG Glucose Monitors
- The SMBG requires patients to prick their fingers with a needle. This is painful, and therefore discourages patients from using their monitors as many times as needed. This problem of patient noncompliance is even worse with pediatric patients.
- With SMBG glucose monitors, it is difficult to constantly record glucose readings and monitor glucose trends over time. Therefore, a patient cannot easily see the pattern in his or her blood glucose levels. Identifying patterns can provide insight into how to better manage blood glucose levels.
- You can miss episodes of high glucose levels due to non-continuous testing if you do not take your glucose reading in a window where extreme glucose level occurs.
Continuous Glucose Monitoring (CGM) Devices
Continuous Glucose Monitoring (CMG) devices measure the blood glucose level without the intervention of the patient. It uses a sensor that is continuously attached to the body of the patient to monitor the patient’s glucose level.
The parts of a CGM Glucose Monitor are:
- A glucose sensor
- A wired or wireless link from the sensor
- A handheld electronic processing and display unit
Depending on how the sensor is attached to the patient, CGM devices can be classified as invasive, minimally-invasive, or non-invasive.
Invasive CGMs have sensors that are implanted inside the body of the patient. These implants can be needles that go under the skin or they can be tiny sensors that are injected into the veins of the patient.
Minimally-invasive CGMs have sensors that slightly penetrate the skin tissue to sense the glucose in the interstitial fluid (ISF) in the skin. These sensors usually have microneedles on them to penetrate the skin. This type of sensor can be used painlessly.
Unlike invasive CGM sensors, minimally-invasive sensors do not go into the vein or blood capillaries to sense blood. Instead, these sensors measure the glucose in the interstitial fluid (ISF) of the skin. This ISF glucose measurement is then mathematically converted to blood glucose measurement.
CGM glucose monitors report glucose levels every one to five minutes. The microneedles that draw the interstitial fluid should be replaced every three to seven days.
Non-invasive CGMs use skin conditions and other body fluids such as sweat, saliva, and tears to measure blood glucose. The CGMs measure glucose levels painlessly. However, non-invasive CGMs still suffer from accuracy problems, and they are still under active research.
Advantages of CGM Devices
- Continuous Glucose Monitors give at-home patients better control over their blood glucose levels by showing them the trends of their blood glucose level. This allows patients to easily optimize diet, treatment, and lifestyle accordingly to better manage their diabetes.
- Implantable Continuous Glucose Monitors, though invasive, allow patients to monitor the glucose in intravenous plasma, which is the gold standard procedure for measuring body glucose. Finger-pricking SMBGs monitor measure glucose in the capillary blood.
- Continuous Glucose Monitors allows a diabetic patient to know his or her “Time in Range“. Time in Range is the percentage of time the patient spends in his/her target blood glucose range. The time in range is a measure of how well a patient is managing his or her diabetes
http://diatribe.org/time-range
Disadvantages of CGM Devices
- Continuous Glucose Monitors(the minimally invasive and non-invasive ones) are less accurate compared to SMBGs. Their measurements drift over time, meaning inconsistent measurements from time to time
- They (the minimally invasive and non-invasive ones) may require periodic calibration with the finger-prick test strip method use in SMGS
- Implantable monitors have a limited lifetime, and they may require the patient to do surgery at least 3 times a year to explant the old sensor and implant a new one.
How to Care for Glucose Meters
- Do not store the test strips of your glucose meter at high temperature for a long time
- Make sure your test strips are clean and uncontaminated
- Store your test strips in a cool dry place
- Take care of the electronics of your glucose monitor as per the conventional guidelines for electronic device care
- The FDA provides recommendations to glucose meter manufacturers on how they can ensure that meters are properly taken care of. The manufacture of your glucose meter will provide you their recommendation on how to take care of your glucose meter. Follow the manufacturer’s recommendations.
Factors to Consider when choosing a Glucose Meter
When choosing a Glucose Meter, these are the important factors to consider:
- Finger-pricking monitor or continuous glucose monitor: Do you want to check your blood glucose when you feel like or you want a system that continuously and automatically measures your blood glucose level? If you want to check your blood glucose when you feel like, then chose an SMBG device, else, chose a CGM device.
- Implantable continuous glucose monitor on invasive continuous glucose monitor: in case you decide to go with a continuous glucose monitor, you need to decide if you want an implantable one or a non-invasive/minimally one
- The amount of blood you need to provide for each test: It is important to know how blood the glucose meter requires. Most modern glucose meters require a minimal amount of blood.
- Test Time: Most glucose test less than 10 seconds, 5 seconds typical
- Wireless connectivity between your monitor and your mobile device: Some monitors allow you to connect your glucose monitor to your mobile phone.
- Your Hematocrit range: Your hematocrit range is the ratio of red blood cells in the blood. Your hematocrit range affects the glucose measurement reported by your glucose meter. Fortunately, some glucose meter measures your hematocrit levels when performing a glucose test, and they automatically correct for error that can be due to your hematocrit level in the glucose measurement
- Price: Blood glucose monitors can range in price from $20 to more than $5000
- Size of the glucose monitor
- Long-term reliability: Does the glucose monitor need periodic calibration?
- Accuracy of the glucose meter(more on this later)
- Digital sophistication: Does glucose meter have wifi capabilities, Bluetooth capabilities, on-device data storage, sends alerts to your phone or doctor when your blood glucose is too high.
Who Should use a Blood Glucose Monitor
- Diabetic patients on insulin therapy
- Diabetic patients on diabetes medication
- People that are prediabetic trying to adopt lifestyle changes to keep their blood glucose level in check
Accuracy of Blood Glucose Monitors
Blood glucose meters need to be accurate because false results can lead to problems like:
- abuse of insulin therapy which can lead to critically low blood sugar
- less control of diabetes leading to fatal consequences
The ISO:15197:2013 is an international standard that specifies the level of accuracy that manufacturers of at-home OTC blood glucose meters should strive for.
This standard requires that 95% of blood glucose results should be
- Within ± 0.83 mmol/L of laboratory results at concentrations of under 5.6 mmol/L (Within ± 15 mg/dL of laboratory results at concentrations of under 100 mg/dL)
- Within ± 20% of laboratory results at concentrations of 5.6 mmol/L (100 mg/dL) or more
Furthermore, there is a similar FDA guidance for at-home glucose meters which recommends that:
- 95% of all measured blood glucose meter values must be within 15% of laboratory results; and
- 99% of meter values must be within 20% of laboratory results
However, according to a study by the Diabetes Technology Society, an independent oversight body, the majority of in-home glucose meters do not meet the ISO and FDA recommendations. In their study of 18 glucose meters, only 6 meet the recommended accuracy levels, as-per the test method used in the study.
https://www.diabetestechnology.org/surveillance.shtml
This inaccuracy tendency of in-home Over-The-Counter blood glucose was confirmed in a similar study of 17 glucose meters by researches from Massachusetts General Hospital Diabetes Research Center.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505415/
The Best Blood Glucose Monitors
According to the research result of the Diabetes Technology Society, the best glucose monitor in terms of accuracy is the Bayer Contour Next Self Monitoring Blood Glucose Meter.
Here is a list of the top 6 glucose monitors in terms of accuracy:
- Bayer Contour Next
- Roche ACCU-CHEK AVIVA Plus
- Arkray Walmart ReliOn Confirm (Micro)
- Agamatrix CVS Advanced
- Abbott FreeStyle Lite
- Roche Accu-Chek Smart View
However, some users may decide to give up a little bit of accuracy for other features of a glucose monitor (e.g smaller size, lower price, Bluetooth connectivity, etc). Therefore, depending on your priorities, what you consider as ‘the best’ may be different from what is on the above list.
What affects the accuracy of blood glucose meters
In addition to the inherently limited accuracy of all blood glucose meters, the following can lead to an inaccurate result of your blood glucose level:
- Taking measurements in a high-temperature environment
- Taking measurements in a high-humidity environment
- Taking measurements at high altitude: In finger-pricking glucose meters, oxygen is involved in the electrochemical detection of glucose. However, oxygen is rare at high attitudes and this leads to inaccurate measurements.
- Hematocrit level of the patient: Some meters specify the hematocrit range over which their sensor is accurate. Using a glucose meter if your hematocrit level is not within the range of the meter will lead to inaccurate results. Furthermore, the hematocrit level of a patient will change if the patient is suffering from anemia, and this might lead to inaccurate blood glucose measurements.
- Contaminants in your hands: especially from handing sugary products like cookies. Wash your hands before using a finger-pricking glucose meter
- Contaminants in your blood due to medication like Acetaminophen that can affect blood glucose reading
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769960/
Future of Blood Glucose Monitoring
Current trends in Blood Glucose Monitor is in the direction of alternative body fluids, other than blood, for the continuous non-invasive monitoring of blood glucose level. Body fluids such as ocular fluids (tears), saliva, and sweat are currently being researched as an alternative to the painful finger-pricking method for monitoring blood glucose.
Efforts are also being directed at using the amount acetone in the breath of a diabetic patient as a measure of their blood glucose level. This type of glucose monitoring uses the same principle as the electronic nose.
The table below shows the range of glucose in these alternative fluids to the blood.
However, with all these new fluids for glucose sensing, the mathematical transformation of the glucose in these alternative body fluids to compute the actual glucose in the blood is always a challenge and many times inaccurate.
Also, the results of monitoring blood glucose with alternative fluids tend to be specific to an individual. This means the measurement values that correspond to high blood glucose in an individual may correspond to normal blood glucose in another individual (depending on the demographics the individual belongs).
However, we live in an era of advanced analytics, we now know new and effective ways to process data. Advanced analytics might be able to use to solve the problem of individual specificity of glucose monitoring with alternative body fluids to develop glucose monitors that are demographic generic.
Furthermore, some big tech companies are investing in glucose monitoring technology. Companies like Google (Verily Life Sciences) and Microsoft are funding research to develop novel glucose monitors. These companies might be able to leverage their technical know-how for innovations in blood glucose monitors.
Also, the development of robust continuous glucose monitors makes it easier for diabetic patients to use artificial pancreas to manage their diabetes. An artificial pancreas combines a continuous glucose monitor with an insulin pump/glucagon pump in a feedback loop.
In an artificial pancreas, when the glucose monitor reads too high/too low value of blood glucose, the insulin/glucagon pump is activated to release insulin/glucagon to drive the blood glucose level back to normal.
References
- Glucose Sensing for Diabetes Monitoring: Recent Developments
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579887/pdf/sensors-17-01866.pdf
- Glucose Biosensors: An Overview of Use in Clinical Practice
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3292132/
- The Increasing Incidence of Diabetes in the 21st Century
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769839/pdf/dst-03-0001.pdf
- The Progress of Glucose Monitoring—A Review of Invasive to Minimally and Non-Invasive Techniques, Devices and Sensors
https://www.mdpi.com/1424-8220/19/4/800/htm
- Review of Non-Invasive Glucose Sensing Techniques: Optical, Electrical and Breath Acetone
https://www.mdpi.com/1424-8220/20/5/1251/htm
- Comparative Accuracy of 17 Point-of-Care Glucose Meters https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505415/
- Factors Affecting Blood Glucose Monitoring: Sources of Errors in Measurement
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769960/
- Technologies for Continuous Glucose Monitoring: Current Problems and Future Promises
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3005068/#b7
- Eyeglasses based Wireless Electrolyte and Metabolite Sensor Platform
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5507201/
- Enzyme‐Based Glucose Sensor: From Invasive to Wearable Device
https://onlinelibrary.wiley.com/doi/full/10.1002/adhm.201701150