10 Tips for Monitoring Your Blood Glucose

By Sherri Shafer

One of the most important advances in diabetes management came in the early 1980s: home blood-glucose monitors. These amazing devices provide critical information that can be used to drive management decisions, improve blood-glucose control, and reduce risks. Monitoring blood glucose reveals how diet, exercise, and medications influence glucose levels, enabling you to take action to avert dangerously high or low levels.

Discovering that your numbers are out of range doesn’t mean that you did something wrong or that you are a bad person. Try to have the mindset that all numbers are data, and data is good. Don’t personalize the numbers; use the data you collect to problem-solve and improve your future. Keep records and share them with your healthcare team, as data provides key details needed to fine-tune your care.

Pick a meter for your blood-glucose needs

The first step in purchasing a blood-glucose monitor is to ask your insurance company which supplies it covers. Insurance companies often limit coverage to a couple of different meters. If your insurance plan covers more than one meter, you can ask your healthcare provider or local pharmacist for advice on which meter to pick. Some meter manufacturers keep the costs low enough to be affordable without insurance. Test strips end up being the biggest expense with any monitoring system.

Safely obtain a blood sample to measure blood glucose

Your hands need to be clean and dry before you obtain a drop of blood. Soiled hands lead to inaccurate readings. A common source of error is the residue from handling carbohydrate-containing foods. Touching fruit or eating finger foods can leave residue on your skin. When you prick your finger, the drop of blood picks up the sugar and your meter reads it as extra glucose. Don’t forget to wash your hands before checking your blood glucose, especially if you’ve previously peeled a banana or an orange! If you aren’t near a sink, you can use alcohol gel or swabs, but make sure your finger is completely dry before you poke it.

You should never share your lancing device with anyone else.

Acknowledge blood-glucose readings errors

Home blood-glucose readings are not exact. You’re unlikely to get an identical reading even if you check on the same finger within seconds of a prior check. Regulations require meters to provide results that are accurate within a plus or minus 20 percent margin of error. However, many are accurate to within 10–15 percent. Regulations are more stringent for accuracy in low ranges, with readings below 75 milligrams per deciliter (mg/dl) required to be accurate to within plus or minus 15 mg/dl. If you question the accuracy of your meter or strips, run a test using control solution, which can be obtained from the manufacturer.

Ensure as much accuracy as possible

Test strips have an expiration date, which is printed on the container. Don’t use expired strips. Strips need to be carried in their original container and stored away from heat, light, and moisture. Don’t store your supplies in a steamy bathroom.

Some meters have test strips that allow for alternate site testing, which means you can obtain the drop of blood from your arm or hand rather than your fingertip. The blood sample from the arm is not as accurate as the blood obtained from the fingertip because blood flow to the surface of the arm is delayed in comparison to perfusion of the fingertips. When blood-glucose levels are in flux, such as when they’re rising after a meal or dropping after exercise, you should use your fingertips. This is especially important if you suspect low blood glucose or are rechecking levels after treating hypoglycemia.

Bring your meter with you to all medical visits. Your healthcare provider can observe your technique and offer suggestions as needed. Use your monitor to check blood glucose at the same time you have blood drawn at a lab, and then compare results to see how your meter measures up to the lab’s standard.

Dispose of blood-glucose measuring lancets and needles properly

Lancet companies recommend that you put in a new lancet each time you check your blood glucose. Most people reuse lancets several times before changing them. Lancets that are overused can become dull, bent, and hurt more. Used lancets, pen needles, and syringes are considered biohazards. They all need to be disposed of properly in a sharps container. If you typically collect sharps in a plastic jug or jar, don’t dispose of that in the garbage can or recycle bin. Used needles can’t go in the regular garbage because they carry the risk of transmitting serious diseases. Recapping needles or lancets is not good enough. Caps can be dislodged, and workers in the waste disposal industry could be accidentally poked. Call your waste disposal company and find out how to properly dispose of sharps in your community.

Vary your blood-glucose test times

How often you should monitor your blood glucose depends on your type of diabetes, current level of control, health history, medications, and risk of high or low blood glucose. For example, if you usually check once or twice daily and typically at the same time of day, such as fasting or pre-dinner, then you know results only for those specific times of day. Mix it up a bit to find out what is going on at other times. Rotate when you check to capture data about blood-glucose patterns before meals, after meals, at bedtime, and overnight.

Know your blood-glucose targets

Speak to your healthcare team about your blood glucose (BG) target ranges for fasting, pre-meal, one to two hours after a meal, before exercise, and before bed. Goals depend upon whether or not you are at risk for hypoglycemia. Targets also depend on age and complexities of other health conditions. Here are some general guidelines:

  • Fasting BG under 115 mg/dl and post-meal BG below 160 mg/dl may be appropriate targets for someone with type 2 diabetes who is not at risk for hypoglycemia.
  • Insulin users are at risk of hypoglycemia, so fasting and pre-meal BG targets are generally 80–130 mg/dl, and post-meal targets are generally below 180 mg/dl. Clarify with your doctor.
  • Pregnancy requires tighter control, so women with gestational diabetes typically aim for fasting BG below 95 mg/dl and one hour post-meal BG below 140 mg/dl.

Keep a log and review your blood-glucose data

You and your healthcare team need blood-glucose data to figure out how to best manage your diabetes. Record your blood-glucose results in a logbook and write the numbers in the column that corresponds to whether the reading was before or after a meal, before or after exercise, before bed, or in the middle of the night. If you count carbs, jot down how many grams you ate. If you took insulin, note how many units you took. Details about your day provide clues to the cause and effect of different variables. Note the time and duration of exercise. If you were hypoglycemic, list how many grams of carb you took to treat it. Recheck glucose levels 15 minutes after treating a low to confirm that blood-glucose levels have returned to a safe level.

Get your A1C checked regularly

The A1C lab test provides details about your “average” blood-glucose control over the past three-month period. Glucose and red blood cells travel together side by side through the same vessels to deliver fuel and oxygen. Glucose can attach itself to blood cells and other proteins in the body. The A1C test measures how much glucose has attached to the hemoglobin protein in the red blood cells in the previous three months. The significance is that glucose may be attaching at similar levels to other places in your body, such as your eyes, nerves, and kidneys, which can lead to complications.

Ask your doctor about the best target level for you. The typical A1C targets for people with diabetes are as follows:

  • For most non-pregnant adults: Below 7
  • For most kids and teens: Below 7.5
  • For some medically complex patients: Below 8

The A1C test is also used to diagnose diabetes. Results are determined as follows:

  • Normal: Less than 5.7
  • Pre-diabetes: 5.7–6.4
  • Diabetes: 6.5 or higher

Having your A1C checked doesn’t replace the need for using your home glucose monitor. Even if your A1C is in the “target range,” you may still have very high blood-glucose levels and very low blood-glucose levels that end up averaging out.

Consider continuous glucose monitoring

A continuous glucose monitor (CGM) is a device that checks blood-glucose levels approximately every five minutes. A water-resistant sensor is inserted under the skin and remains in place for six to seven days, depending on the brand. Blood-glucose readings are transmitted wirelessly to a receiver or to an insulin pump. The display screen on the receiver or the pump shows blood-glucose values and also indicates trend lines predictive of the direction the blood glucose is headed as well as the rate of change. You can see whether your blood glucose is stable, rising, or falling and how fast.

The CGM device and ongoing supplies are expensive. Check with your insurance company to see whether you qualify for coverage.