Different Monitors Different Readings

This Saturday morning I woke up with a rather high BGL(Blood Glucose Level). My Accu-Chek Performa read 11.4mmol/L (205mg/dL) and the FreeStyle Optium 13.4mmol/L (241mg/dL). The previous morning the Performa read 3.3mmol/L (59mg/dL). No Optium test was taken.
Most people would ask “What is going on?” and doubting the accuracy of their meters.
I must state that I have found both the Abbott Optium and the Roche Performa to be very reliable and accurate meters. I have collected a lot of data and record BGL prior and after blood have been taken by my Doctor for every 3 monthly HbA1c blood tests.
Because I have been diagnosed as having Brittle Type 1 and was very quickly developing neuropathy in my feet back in 2010, I needed to know that the tests were correct.
I discussed these test anomalies with my Doctor and Endocrinologist. After ruling out all contaminations, e.g; not following the correct procedures prior to testing, humidity, temperature, sunlight and contaminated or faulty strips, I did the research into why these variations were occurring.
I ‘m a fisherman with a small cane farm doing all my own bookwork which, I know contributes to my unstable BGL. I have a background in Sugar Chemistry and know there are Doctors, Microbiologists and Molecular Scientists who read and contribute to this forum so it will be interesting to see your comments.
My “Before and After” Performa and Optium Tests have been different to my Blood Tests. Some are extreme.
Why and how did I find out something was wrong with the results?
I have Gilbert’s Syndrome and at times suffer from extreme hey fever. Murphy’s Law has had a big influence prior to some Blood Tests e.g; Changing a flat tyre on a hot day prior to a fasting Blood Tests, running 400 meters to another appoint and an appointment delayed for 3 hours.
The results that made me query the BGL at the time of the test was the 3 hour delay.
I had injected my morning Levemir to bring down a higher then normal BGL and increased my NovoRapid for my breakfast before working on the tractor, then drove to town.
This was not a fasting Blood Test but my appointment was delayed by 3 hours. When in town my BGL fell to below 5.0, so by law, I could not drive. Walking would lower my BLG and sitting caused my BGL to rise. The Doctors Practice was busy so I had to walk to the Pathology Lab for blood to be taken, a 500meter walk.
Results below.

Fri 27th Feb 2015 8th May 3.00pm Dr.
Time BGL BGL Carbohydrates Wt g Carbs Protein Wt g NovoRapid BGL BGL BGL BGL BGL
9.46pm 14.9 Bed Thu 26th Grams Levemir 30min 60min 90min 2hrs 3hrs
6.18am 13.2 20
6.20am 7
7.06am 11.8 Coffee & Xylitol 12 12 Computer work
FC Milk 300 15.3
7.20am 12.3 Grapes 150 28 Active physical work. Working on Slasher
8.36am 5.4 Grapes 150 28 Shower for town.
11.38am 4.1
11.46am 4.0 3.5 New FreeStyle Optium Test Strips. Tested @ Chemists Walking since 11.38am(BELOW 5.0)
11.59am 3.9 3.0 (Test Prior) Blood Test Before Blood Tests Blood test results 2.9 Note: The “AFTER TEST” is under 30 seconds from the Blood Test.
12.03pm 4.2 3.4 (Test After) 2.9 After Blood Tests Injected NovoRapid because of rising BGL (Usual response when activity stops.)
12.04pm 6
12.15pm Pie Chicken & Peas Walked 100m to park to eat pie. (DID NOT TEST BECAUSE BELOW 5.0.)
12.55pm 5.9 5.4 Stone Fruit 320 Walking around town & shopping.
1.48pm 9.4
1.50pm 8.8 9.2
1.51pm 9.1 8.9
3.12pm 5.9 Grapes 150 28 30
Coffee & Xylitol 12 12
FC Milk 300 15.3
5.37pm 2.8 Dextrose 10 10
7.30pm Gin & Diet Tonic Water
7.31pm 5.1 Meal High Protein 11
Eggs Crab Chicken
Grapes & Plumbs Not Weighed
Yoghourt 300 35.1
Pears in Syrup 215 31.6
10.12pm 7.4

TESTS: Prior & After. This is a normal BGL reaction if I have NO BOLUS on BOARD for BGL to rise quickly if I stop Physical Activity. BGL can rise from 2.8 to 3.5 within 10min(NO FOOD EATEN).
I know that the “Random BGL Blood Test” can not be correct as I did not have any Hypo symptoms and 40min later after the Pie BGL was 5.9.
Could the BGL be incorrect because the sample was not “Deproteinized” thus allowing the Red Blood Cells to take up Glucose?

Sat 28th Feb 2015 8th May 3.00pm Dr.
Time BGL BGL Carbohydrates Wt g Carbs Protein Wt g NovoRapid BGL BGL BGL BGL BGL
10.12pm 7.4 Bed Fri 27th Grams Levemir 30min 60min 90min 2hrs 3hrs
3.08am 5.7 Computer Work. HAY Fever.
4.05am 7.0 8.1 20 Back to bed.
8.12am 10.0 10.1 Coffee & Xylitol 12 12 7 Computer Work.
FC Milk 300 15.3
Grapes 150 28
11.18am 8.1 9.4 Plum 102 ?
12.25pm 8.9 10.0 Plum 96 ? 5
Grapes 150 28
2.44pm 2.5 1.4 Dextrose 20 20
Grapes 136 26
3.03pm 4.3 4.0 Coffee & Xylitol 12 12
FC Milk 300 15.3
Cheese 76
3.44pm 8.4 8.1 30
Olives 119 5
Yoghourt 431 58.6
6.04pm 5.9 5.2 Gin (50) & Tonic Water 400 35.2 7
Nectarine 98 Scrambled Eggs
Grapes 240 46 Crab & Tomato 280
8.33pm 11.4 13.3

I was in trouble with my Doctor until we both worked out what had had gone wrong. Because the Blood Glucose test came from the same vial for the Bulirubin (Gilbert’s Syndrome), the blood sample was not “deproteinized”. It takes 10 to15 minutes for the blood in the vial to coagulate before it can be centrifuged. This allowed sufficient time for red blood cells to take up glucose because there was IOB (Insulin on Board) and I had been physical activity prior to bloods been taken.
The only times that Blood Test Glucose Levels and both meter tests correspond for me, are when BGL are in normal range( 4.8 – 6.0mmol/L) when both meters read the same and the before and after test do not change, with no fast acting insulin on board and no physical activity prior to tests.
A disturbing trend that I have noticed with my tests is, that even if BGL are close to normal and the Optium is higher than the Performer but both are rising, the Blood Test is always higher than the highest reading. In the case below, I knew that the Blood Test was the more correct reading and actually could have been, higher because it is only the liver that can return Glucose back into the blood and only in the form of alpha Glucose. It is a bit disconcerting for me when the Optium is reading higher then the Performer as my BGL could actually be higher then both meters are saying.
See Below:
Thu 28th April 2016 5th May 2.00pm Dr.
Time BGL BGL Carbohydrates Wt g Carbs Protein Wt g NovoRapid BGL BGL BGL BGL BGL
Grams Levemir 30min 60min 90min 2hrs 3hrs
11.13pm 13.2 Bed Wed 27th 2 High BGL.Injected Novorapid before bed. Back FROM FISHING
2.42am 2.5 Dextrose 15 15
2.50am 2.9 2.9
3.40am 3.9
5.37am 2.6 Dextrose 15 15
5.42am 3.2 2.8
7.09am 4.2 4.2
7.30am 4.4 4.9
7.56am 5.3 5.0 DID NOT inject insulin BECAUSE FASTING BLOOD TESTS. (Drove to town after BGL reached 5.0.)
8.34am 6.0 6.5 (Test Prior) Blood Test Before Blood Tests
8.41am 6.2 7.2 (Test After) 8.2 After Blood Tests 22
9.11am 5.9 6.0 Chicken Pie & Peas 5
10.29am 9.3 Normal Food
3.46pm 8.9 28
6.07pm 2.5 2.2 Dextrose 15 15
6.21pm 4.0 4.4
8.08pm 6.1 Normal Meal 5

There were only a few occasions when BGL were between 8 – 10mmol/L and the Performa read higher then the Optium. Blood tests came back between the meter readings but much closer to the Performa result.
I have written to both Roche and Abbott but neither company addressed the variations that occur between different makes of meters.
I know the only ways to obtain a true and precise Glucose readings from a blood sample is first to deproteinize the sample (perchloric acid has been used for this purpose) then using HPLC (High Performance Liquid Chromatography ) to determine the Glucose level. The other way to obtain correct Glucose level is by titration. This would also would be complex but a simple reducing sugar titration would detect all other simple sugars (Fructose, Fucose, Glactose,Mannose, Xylose) that could be in the blood. A fasting Blood Test would all but eliminate these other simple sugars as the liver would by then be the only supply of energy, namely alpha Glucose. Compared to Glucose Meters, titration is still a very slow process.
Personal Glucose Monitors are the best technology available because they are affordable, give instant results and are accurate, giving good repeatability of tests WHEN EVERY THING IS IN A STEADY STATE AND BLOOD GLUCOSE LEVELS ARE WITHIN THE NORMAL RANGE.
Even the good brands of meters rely on enzymes as a component in their technology to deliver the Blood Glucose reading. I will not go into the chemistry of simple sugars but will say, even the glucose we can metabolize, D (+) Glucose comes in two forms called anomers; α- and β-glucose which mutarotate through the open chain aldehyde form and enzymes favour different structures of a molecule and react differently under different concentrations. Because each company use slightly different combinations of reagents and obtain enzymes by different methods, you may see variations between two different makes of meters even from the same drop of blood.
If your doctor orders a Random Blood Glucose which comes from the same vial involving protein tests, this Blood Glucose Test may not be accurate. For a Blood Glucose Test to be 100% accurate you have to be fasting and the sample has to be immediately deproteinized then the correct analysis of the blood has to be followed.
Before you call you meter “Liar” then throw it and bounce it off the wall because you do not believe the reading, remember these meters are the best, cheapest and quickest method to obtain BGL’s but they have their limitations.
It took me over 3 years of recorded data before I worked out why the meters that I use gave different readings. I now use the variations between meter readings to change my daily insulin injections.
I know this is a controversial subject and I hope I have not confused people more about the accuracy of Blood Glucose readings and which are the best meters. I repeat again, all good makes of Glucose Meters will give similar readings if every thing is normal. If BGL are outside of the preferred range, only trial and error and following the correct set of procedures for that set of circumstances can get levels under control. Having faith in your meter reading is a must if you are going to stabilize the unusual events that occur in the management of your diabetes.
Sorry I don’t think the data section copied across correctly.

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This post was my first with a topic that I had created and did not see the complete page layout before I sent the article. The spreadsheets were completely scrambled. Here are the before and after as well as the blood tests results.

Fri 27th Feb 2015
Performa Optium Blood Test Result
11.59am 3.9 3.0 Test Prior 2.9
12.03pm 4.2 3.4 Test After

Thu 28th April 2016
Performa Optium Blood Test Result
8.34am 6.0 6.5 Test Prior 8.2
12.03pm 6.2 7.2 Test After

I checked one of my meters against another and got similar but different numbers. I had my BG checked by the nurse at the Doctors office. A third similar but different number. I just don’t sweat it. It is not a big deal.

Rice is dangerous. Lettuce is almost negligible. Good luck.

Yes, I agree with you Robert17 if the variations are small. It maters to me if BGL’s are close to 5 and I have to drive; the Performa at 5.4mmol/L (97mg/dL) and I am OK and the Optium 4.1mmol/L (74mg/dL)and I can not as would be breaking the Australian Law.

I have had a Blood Test come back at 8.2 with prior and after readings from 6.0 to 7.2.

Knowing that from my blood tests that a Optium reading of 10mmol/L and a Performa reading of 8mmol/L means that my true level could be 11mmol/L does worry me if I had only testing with the Performa. A 3mmol/L (54mg/dL) discrepancy from what could be the true reading is of concern for me especially if I have been at this level for hours while asleep.

I start sweating at 60 mg/dL. And right now I am working everyday (Retirement = March 31 ) so I need to keep my glucose at or near 140 mg/dL. As I work, the numbers descend toward 99 mg/dL. Lunch and then I try again to get the glucose to 140 mg/dL. Then it will slowly descend to 99 mg/dL.

If I forget to use my insulin, the glucose soars to 200 + mg/dL. A forgiveable disaster. Use insulin; get back on track.

I suggest that you pick one meter and work with it. Give yourself a range that you like and aim for it. And if you feel yourself going low, with sweating and strong hunger and shakes, then treat it with glucose tablets and change your range. In other words, use your meter EVEN THOUGH you don’t believe it at face value.

Experiment and tell me how it works. Use the meter as a tool.

I turned 65 during the first week of January this year but I am a primary producer so I will not be retiring just yet.

I do not know if you have a chemistry background Robert17, but a way to describe how most enzymes work is, only one key will only open one lock e,g; an enzyme will only attach or react with one molecular structure.

Below is a quick explanation of my theory why different meters give different readings when there are changers happening quickly in the blood: Bolus Insulin on Board, Physical Activity, Fight or Flight, Hypo Correction or a status quo scenario that has existed for a period time and BGL start to rise; DP (Dawn Phenomenon).

From my chemistry, I knew that the Glucose anomers were α- and β-glucose which mutarotate through the open chain aldehyde form, in aqueous solutions with a neutral pH. At equilibrium the α- and β ratio is about 36:64 at room temperature.

This made me wonder if this was the reason behind the different readings I was seeing from the meters. From my research, I also knew that it is only the liver that can return Glucose back into the blood and only in the form of alpha Glucose.

I mixed my own Glucose solutions and was surprised to see (although not the same ratio) the Optium reflected the α Glucose ratio with a lower reading and the Performa, the β Glucose ratio with a higher reading.

I use the Performa as my main meter, but if BGL’s are higher then normal then I will do a follow up test with the Optium.

My Hypo awareness is 2.8mmol/L (50mg/dL) and I rarely fall below this level. I just can not drive a tractor straight or ensure that the cane goes in the bin when I am harvesting cane if I reach this level. My Doctor is not impressed with this level but I have never gone into a coma and it is quite a while since I have seen a reading below 2.0mmol/L (36mg/dL) and these levels are due to me for ignoring the Hypo signals.

Forgive this question. What “glucose solution” are you mixing ?

For the first 20 years I didn’t test my glucose. It wasn’t in my budget until 1990ish. My only option was peeing on a stick that turned color to help me guess how much sugar had been spilled from my bloodstream to my urine over the last 2 / 3 / 4?? hours. The meters are great. I check how close they are when I have blood work done. If there is a significant difference I get a new meter the next time I purchase test strips. Then I compare old and new for accuracy. This will always be more accurate than peeing on a stick :slight_smile: I am happy with my A1C so it works for me.

I use Dextrose which is Glucose monohydrate, which is D (+) Glucose and a water molecule. I had the solution checked at the local sugar mill lab and it mutarotates. To make alpha Glucose you have to crystallize it using Methanol as a solvent and beta Glucose the solvent is Acetic Acid.

My Performa meter is 4 years old and still reading true. The way I test it is against another Performa meter using the same drop of blood.

I quickly gave up comparing before and after readings with Blood Tests because they only matched when BGL’s were normal and both the Performa and Optium read the same.

We are almost there… You are making such a solution for what ? What use is alpha Glucose to a diabetic ?

Google Glucose and Glucose Transporters, this will help you.

I use Dextrose to treat Hypos, one tablespoon is 10-12 grams. It is a very cheep Hypo fix, it stores well in a container and I am not tempted to finish an open packet of Glucojels.

When you dissolve crystalline Glucose in water be it alpha Glucose, beta Glucose or Glucose monohydrate when equilibrium is reached, the α- and β ratio is about 36:64 at room temperature. With Dextrose it takes about 3 hours for equilibrium to be reached and this ratio difference is what I am recording with the Performa and Optium meters.

Cellulose, starch and glycogen are all the same molecules, Glucose.

Glucose is the most important monosaccharide( Also falls in to the classification of a Carbohydrate), also called dextrose because the form which occurs naturally is optically active and dextrorotatory (Positive) (Rotates plane polarized light to the right.) The blood of mammals consists of about 0.1% glucose and is essential for their life. Glucose, either free or combined with other molecules is probably the most abundant organic compound. There are two pure crystalline forms of Glucose, Alpha and Beta. When Glucose, in its alpha or beta form, is dissolved in water, the equilibrium is about 36% alpha and 64% beta with less than 0.2% of the open chain aldehyde. Starch is from alpha Glucose which is the Carbohydrate reserves in many plants; e.g. Cereals, Rice, Sweet Potato, Potato, Yams and Corn. Cellulose is from beta Glucose and is the main structural material of plants. The most complex Carbohydrate that we can effectively digest is starch. It is hydrolyzed (broken down) into separate glucose molecules by enzymes through the digestive process and the Glucose is absorbed from the intestine into the blood. The blood transports Glucose to the liver, muscles and other sites where it is converted to GLYCOGEN which is our Carbohydrate reserve. Glycogen is the analog of starch and sometimes is called animal starch. Glycogen resembles starch but is more ball like and structured in appearance than starch and Glycogen has a lower molecular weight. Like starch, Glycogen is made from alpha Glucose.

Glycogen is made and stored mainly in the cells of the liver (up to 8% by weight) and muscles (1 to 2%) but the muscles can store more because of there larger mass. The amount of Glycogen stored in the body mainly in the liver, muscles and red blood cells mostly depends on physical activity, basal metabolic rate and eating habits. Muscle cell Glycogen appears to function as an immediate reserve source of available glucose for muscle cells and the glucose can not pass back into the blood. In contrast the liver can break down Glycogen into glucose to be sent via the blood to where ever it is required.