Is my Dexcom sensor accurate?

b {font-weight: bold;} ol {list-style-type:decimal; margin-left:40px;} .flex-row {align-items:center; display:flex;} .flex-row--tables {display: flex; flex-wrap: wrap; justify-content: space-around;} table {margin-bottom: 20px;} th, td {font-size:20px; text-align:center;} .node-type-question .pane-node-body table th, .node-type-question .pane-node-body table td {background-color:transparent; border-color:black; border-width:2px; color:black; font-weight:bold; line-height: 1.1; max-width:57px; min-width:57px; padding:6px 10px;} .node-type-question .pane-node-body table th:nth-child(2), .node-type-question .pane-node-body table td:nth-child(2) {background-color:#4fb736; color:white; max-width:134px; min-width:134px;} .flex-row {flex-direction: column;} .row__image {width:150px;} .row__image--test {order:2;} .row__image {width:100px;} .row__image--intro {width:200px;} .row__image--left {margin-right:20px;} .row__image--right {margin-left:20px;} DEXCOM G6 CONTINUOUS GLUCOSE MONITORING SYSTEM (DEXCOM G6) READING AND METER VALUE Whether you’re new to Dexcom or experienced, review product instructions before using the Dexcom G6. Keep using your BG meter to make treatment decisions until you know how Dexcom works for you. Your meter gives you one number, if you test twice (using the same or a different meter) it gives you another number, and your Dexcom G6 gives you a third. What do you do with all those numbers? The test The test your doctor does is considered a more accurate glucose number than any products you use at home. Both meters and Dexcom G6 are compared to that doctor’s test to measure accuracy in clinical studies. They aren’t compared to each other. Because of this, the Dexcom G6 reading (G6 reading) and meter value are unlikely to be exactly the same number, but they should be close. Compare the meter and your Dexcom G6 to see how closely the numbers match each other: if your G6 reading and meter value are within what we call the 20 rule (also known as the %20/20 rule), they match closely. The rule To use the 20 rule follow these steps using the table below: Look up your meter value in the green middle column. The left G6 – column shows the low range for a G6 reading that’s a close match. The right G6 + column shows the high range for a G6 reading that’s a close match. For example the orange highlighted row shows that if your meter value is 100 mg/dL, your G6 reading is a close match if it’s between 80 and 120 mg/dL. G6 - Meter Value mg/dL G6 + low 40 60 low 50 70 40 60 80 50 70 90 64 80 96 72 90 108 80 100 120 88 110 132 96 120 144 104 130 156 112 140 168 120 150 180 128 160 192 G6 - Meter Value mg/dL G6 + 136 170 204 144 180 216 152 190 228 160 200 240 168 210 252 176 220 264 184 230 276 192 240 288 200 250 300 208 260 312 216 270 324 224 280 336 G6 - Meter Value mg/dL G6 + 232 290 348 240 300 360 248 310 372 256 320 384 264 330 396 272 340 high 280 350 high 288 360 high 296 370 high 304 380 high 312 390 high 320 400 high Good fingerstick practices When using your meter, make sure: Your test strips are stored as directed and not expired. Your hands are clean for the fingerstick. Wash your hands thoroughly with soap and water (not hand gel) and dry them. Then test. There are times when the numbers temporarily don’t match, but are likely to become closer over time. For example: Sensor’s first day. With newly inserted sensors, the differences between your meter value and the G6 reading may be greater. Generally, the match gets closer over the first 24 hours. Glucose changing quickly. When your glucose is changing quickly, it’s more difficult to compare numbers. The meter and Dexcom G6 measure glucose from different sources (blood and interstitial fluid), and blood glucose changes a little before interstitial fluid glucose. The match gets closer and easier to compare when your glucose stabilizes. Pressure on sensor. When something is pressing on your sensor it can affect your G6 readings. The match should get closer after the pressure is relieved. To determine what to do, watch your G6 readings over several hours. If the readings are always higher (or always lower) than your meter values and always outside the 20 rule, consider calibrating. Also consider calibrating if your Dexcom G6 and meter numbers don’t match and your expectations or symptoms fit the meter value, not the G6 reading. Calibration Calibrating your Dexcom G6 with your meter is never required. It can make the Dexcom G6 more accurate or less accurate compared to the lab result, but it should bring the G6 readings closer to the meter values. When calibrating, make sure: You enter the calibration within 5 minutes of taking a fingerstick. You don’t calibrate during Sensor Error. If you’d like, you can calculate the 20 rule on your own. The Dexcom G6 reading must be within: 20% of the meter value when the meter value is 80 mg/dL or higher 20 mg/dL of the meter value when the meter value is under 80 mg/dL Please note: the information listed here is applicable to Dexcom CGM users within the US only.

Last Updated: September 10, 2020

DEXCOM G6 CONTINUOUS GLUCOSE MONITORING SYSTEM (DEXCOM G6) READING AND METER VALUE

Whether you’re new to Dexcom or experienced, review product instructions before using the Dexcom G6. Keep using your BG meter to make treatment decisions until you know how Dexcom works for you. Your meter gives you one number, if you test twice (using the same or a different meter) it gives you another number, and your Dexcom G6 gives you a third. What do you do with all those numbers?

The test

The test your doctor does is considered a more accurate glucose number than any products you use at home. Both meters and Dexcom G6 are compared to that doctor’s test to measure accuracy in clinical studies. They aren’t compared to each other. Because of this, the Dexcom G6 reading (G6 reading) and meter value are unlikely to be exactly the same number, but they should be close. Compare the meter and your Dexcom G6 to see how closely the numbers match each other: if your G6 reading and meter value are within what we call the 20 rule (also known as the %20/20 rule), they match closely.

The rule

To use the 20 rule follow these steps using the table below:

Look up your meter value in the green middle column.
The left G6 – column shows the low range for a G6 reading that’s a close match.
The right G6 + column shows the high range for a G6 reading that’s a close match.

For example the orange highlighted row shows that if your meter value is 100 mg/dL, your G6 reading is a close match if it’s between 80 and 120 mg/dL.

G6 -	Meter Value mg/dL	G6 +
low	40	60
low	50	70
40	60	80
50	70	90
64	80	96
72	90	108
80	100	120
88	110	132
96	120	144
104	130	156
112	140	168
120	150	180
128	160	192

G6 -	Meter Value mg/dL	G6 +
136	170	204
144	180	216
152	190	228
160	200	240
168	210	252
176	220	264
184	230	276
192	240	288
200	250	300
208	260	312
216	270	324
224	280	336

G6 -	Meter Value mg/dL	G6 +
232	290	348
240	300	360
248	310	372
256	320	384
264	330	396
272	340	high
280	350	high
288	360	high
296	370	high
304	380	high
312	390	high
320	400	high

Good fingerstick practices

When using your meter, make sure:

Your test strips are stored as directed and not expired.
Your hands are clean for the fingerstick. Wash your hands thoroughly with soap and water (not hand gel) and dry them. Then test.

There are times when the numbers temporarily don’t match, but are likely to become closer over time. For example:

Sensor’s first day. With newly inserted sensors, the differences between your meter value and the G6 reading may be greater. Generally, the match gets closer over the first 24 hours.
Glucose changing quickly. When your glucose is changing quickly, it’s more difficult to compare numbers. The meter and Dexcom G6 measure glucose from different sources (blood and interstitial fluid), and blood glucose changes a little before interstitial fluid glucose. The match gets closer and easier to compare when your glucose stabilizes.
Pressure on sensor. When something is pressing on your sensor it can affect your G6 readings. The match should get closer after the pressure is relieved.

To determine what to do, watch your G6 readings over several hours. If the readings are always higher (or always lower) than your meter values and always outside the 20 rule, consider calibrating. Also consider calibrating if your Dexcom G6 and meter numbers don’t match and your expectations or symptoms fit the meter value, not the G6 reading.

Calibration

Calibrating your Dexcom G6 with your meter is never required. It can make the Dexcom G6 more accurate or less accurate compared to the lab result, but it should bring the G6 readings closer to the meter values.

When calibrating, make sure:

You enter the calibration within 5 minutes of taking a fingerstick.
You don’t calibrate during Sensor Error.

If you’d like, you can calculate the 20 rule on your own. The Dexcom G6 reading must be within:

20% of the meter value when the meter value is 80 mg/dL or higher
20 mg/dL of the meter value when the meter value is under 80 mg/dL

Please note: the information listed here is applicable to Dexcom CGM users within the US only.

LBL019054 Rev001

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