HypoGlycemia and Plasma meters

[Oldvatr]

I was recently on another thread that was becoming sidetracked into a discussion centered around having to replace my bgl meter for one that is calibrated for Plasma Equivalent. In the interest of science I am moving that discussion here for further discussion, I have researched this quite extensively, but so far I remain confused. I do NOT have an answer yet,

When bgl meters first came out they were calibrated for use with capilliary blood, and this was termed Whole Blood (WB) calibration. Recently ALL new meters are required to be calibrated differently, called Plasma Equivalent (PE), and these meters now display results that are some 12 to 15% higher than the older WB meters. So PL= WB x 1.12, or WB = PE x 0.88. There is a section on the Home page of this site describing this with a convertor tool.

How do we tell what our meter is calibrated to? The answer is generally in the blurbsheet that comes with the strips. In the ones I have for my meters there is a section on accuracy or performance which describes how the strips compared to a YSI Blood Analyser used during the ISO certification testing. If there is mention of an adjustment of 1.12 to the readings before comparison was done, then the strips go in a meter that measures Whole Blood. If the comparison is direct, then the strips are PE. Note the YSI is a lab instrument used for analysing venous blood, and gives results as Plasma.

So my NEO meter is WB and my SD Codefree and CareSense Dual are both PE. I am now certain of this, so next month when I am forced by my CCG to ditch my trusty NEO, then I will have a meter that reads 12% higher than I am used to. So what adjustments will I have to make?

Firstly the target ranges for BGL control. I have found that the Joslin Centre in USA has recently updated their advice to be PE compatible, and they no longer support WB meters. So going by their 2hr PP range for a diabetic this is 5.0 to <10 mmol/l in UK values. As it happens the ADA and the Mayo Clinic also have these same figures, as well as other US sites and magazines. (but in mg/dl). So it seems they are all PE now, But in the UK, NICE, DCUK and DUK are all reporting this same upper linit as being 7,8 to 8,5 mmol/l for a T2 diabetic, or 7,8 to 9 for a T1D. Now a PE value if 180 mg/dl becomes 8.8 mmol/l in uk money, which is close to the range given by @daisy1 to newbies. So it strongly suggests that the UK data is still in Whole Blood terms.

I have to go visit my OH in hospital now, so will pick this up when I get back. I need to discuss the effect of this on hypo readings, and also on DVLA advice.

 

[tim2000s]

I need to discuss the effect of this on hypo readings, and also on DVLA advice.

I don't think you have anything to worry about. Quoting from this study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1838950/

The sequence of responses to falling plasma glucose concentrations (1) is illustrated in Figure Figure1.1. Initially, declining plasma glucose levels activate defenses against hypoglycemia. Physiological defenses normally include decrements in pancreatic β cell insulin secretion as glucose levels decline within the physiological postabsorptive plasma glucose concentration range (approximately 3.9–6.1 mmol/l [70–110 mg/dl]). The glycemic threshold for decreased insulin secretion is approximately 4.5 mmol/l (81 mg/dl). Increments in pancreatic β cell glucagon and adrenomedullary epinephrine secretion (among other neuroendocrine responses) normally occur as glucose levels fall just below the physiological range (threshold equal to approximately 3.8 mmol/l [68 mg/dl]). If these defenses fail to abort the hypoglycemic episode, lower glucose levels trigger a more intense sympathoadrenal response that causes neurogenic (or autonomic) symptoms; neuroglycopenic symptoms occur at about the same glucose level (threshold equal to approximately 3.0 mmol/l (54 mg/dl). The perception of symptoms, particularly neurogenic symptoms, prompts the behavioral defense, the ingestion of food.

Therefore a plasma calibrated meter is correctly reflecting what will happen in the case of hypoglycaemia and there is no need for change. Whilst you may have thought yourself hypo, when looking at a whole blood meter, physiologically, you were not. Meters have generally moved to Plasma calibration so it's unusual to find a whole blood meter and I believe all the ISO 2013 compliant meters are plasma.

The Optium Neo is not a Whole Blood calibrated meter, but a Plasma Calibrated meter, as detailed in the tests done here, where it states:

Comparative Methods
The YSI 2300 Stat Plus glucose analyser served as the comparative method in the clinical and laboratory studies. The YSI whole blood glucose results were multiplied by 1.12 to obtain plasma equivalent glucose values for comparison with the test strip results. The YSI glucose analyser has metrological traceability to NIST certified reference material.

Many Abbott Freestyle Libre users state that the Optium test strips, used with the Libre (a plasma calibrated glucose monitor) regularly report lower glucose levels than other meters.

So what does this mean?

• For hypo readings? They are now more accurately reflecting hypos when using plasma.
• For the DVLA? The meters are accurately reflecting hypos, and their guidance is good.
• For you? I postulate that your trusty Neo always read slightly lower, as is consistent with Optium strip models.
• What adjustments do you need to make? Given your physiology is dependent on diffusion of glucose from plasma not whole blood, treat plasma readings as reasonable. That you have variation across meters is not attributable to Plasma or Whole Blood.

 

[Oldvatr]

I don't think you have anything to worry about. Quoting from this study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2903977/



Therefore a plasma calibrated meter is correctly reflecting what will happen in the case of hypoglycaemia and there is no need for change. Whilst you may have thought yourself hypo, when looking at a whole blood meter, physiologically, you were not. Meters have generally moved to Plasma calibration so it's unusual to find a whole blood meter and I believe all the ISO 2013 compliant meters are plasma.

The Optium Neo is not a Whole Blood calibrated meter, but a Plasma Calibrated meter, as detailed in the tests done here, where it states:


Many Abbott Freestyle Libre users state that the Optium test strips, used with the Libre (a plasma calibrated glucose monitor) regularly report lower glucose levels than other meters.

So what does this mean?

• For hypo readings? They are now more accurately reflecting hypos when using plasma.
• For the DVLA? The meters are accurately reflecting hypos, and their guidance is good.
• For you? I postulate that your trusty Neo always read slightly lower, as is consistent with Optium strip models.
• What adjustments do you need to make? Given your physiology is dependent on diffusion of glucose from plasma not whole blood, treat plasma readings as reasonable. That you have variation across meters is not attributable to Plasma or Whole Blood.

I feel that you have just patted me on the head, and told me not to worry my pretty little head over this. I have read your post, and I do not think it answers any of my concerns at all.

Fitstly, the first link you provide takes me to a scientific treatise on AST and CGM, which actually have no relevance to my situation. It discusses interstitial fluid and subcutaneous issues that are nothing to do with the capilliary blood that is involved in a fingerprick test, so you cannot draw the same conclusions,

The section you have extracted into your post is something I have seen before, and understand, but this is often trotted out by well meaning T1D's when a T2D asks about hypo's. The conclusion drawn is that T2D will not experience hypoglycemia since the body has protection mechanisms that kick automatically into place, Unfortunately, as a T2D I have an endocrine system that is damaged and is not functioning in the way that scientists postulate for a healthy person, So I do not necessarily react as described. Also I am on a hypoglycemic type of medication that is noted for being able to cause hypo episodes, and this appears to be responsible in my case. Whilst I agree that my episodes are not as severe as an insulin-caused hypo, and I am able to control them well as a result, I nonetheless DO suffer the effects of low bgl, and there are times when I MUST NOT DRIVE or operate machinery. Eating a small amount of carbs is sufficient to cancel these symptoms, so a sponful of sugar most certainly makes the wheels go round.

At the moment, I am hypo aware, but there may come a day when I lose this ability, and this is why I am concened about the meter performance issue. The dilemma I have is that no one so far has been able to declare with authority (and in writing) either the basis for the published bgl limits for DVLA or hypo events, and even the UK treatment target ranges are suspect. I do not have a defined goal to meet at the moment, and this is a dilemma.

When I lose my meter next week, I am taking on a replacement meter that reads higher than what I am used to, and this is worrying since it will no longer reflect the way I feel physically. My hypo's are NOT psychosomatic, The symptoms come first, the test follows. In future I will be getting results that will allow me to drive and any post accident investigation will show I 'followed' DVLA requirements to the letter since my recorded bgl at start may well be over 5,0 mmol/l. If I am not hypo aware at the time, then I could be unknowingly placing myself and other road users in danger.

Personally I am not concerned about my low bgl levels. It is my choice to run with a daily average of around 5.9 tp 6.2 mmol.l, and whilst I usually maintain my swings between 4.7 and 7.4 mmol/l, there are occasions when I go outside this comfort zone. Obviously I could give up taking Gliclazide (and that is a design aim I have one day this coming year) but then I lose my strips on scrip so I need to feel secure before that happens. OR, I could up my daily carb intake, come out of ketosis, and push my daily average above 7.5 mmol.l But this will increase risk of complications long term. If my hypo's were deep, then that too would be detrimental long term, so I need a meter I can rely on to fine tune my treatment.

At the moment I feel like an army sniper where someone (CCG) has stepped on my glasses and trashed them.

Moving swiftly to your last point, about the NEO being Plasma Equivalent, that may b true of brand new ISO )2013) compliant machines, but mine is definitely acting like a whole blodd machine. For 13 months it has consistenly been measuring between 1 and 3 mmol/l lower than my SD Codefree meter. When I have gad a point sample where the Codefree reads lower than the Neo, then I retest, and so far I have not had any instance where it ahs remained lower than the NEO. the lowest Codefree reading in 13 months has been 4,3 mmol/l, and the lowest NEO reading has been 2.1 mmol/l. Given that each meter is allowed 0.83 mmol error at this range, then it is difficult to say which meter is wrong since a difference of 1.66 is within specification. So far neither supplier has offered to replace their meter since both say theirs is meeting spec if they pass the calibration fluid check, which they do. I have asked Abbott Customer care to confirm that my meter should be plasma equivalent, as stated in your post, Aftey a discussion in their office they came back that the meter probably is Plasma, but they cannot find any official statement to this fact in the literature, so are not able to provide me with written evidence, It is not mentioned anywhere that I can see.

As regards certification evidence, I do not take this as being foolpoof. We have had experiences ( Challenger O rings, VW emissions, et al) where evidence can be misrepresented or covered over, and as a former aerospace Engineer, I too have seen many attempts to cook the books during qualification, so I am naturally sceptic. I note that the ISO test results reports for the SD Codfree and the Caresense Dual do not mention adjusting either sets of results before comparison, so appear to have been made on a direct 1:1 basis. Of course, it may be a different lab, so this is not a definitive conclusion. The YSI 2900D can present either whole blood or plasma readings by simple menu selection.

 

[tim2000s]

@Oldvatr You've misunderstood the point that I have made. The first link contains the clear statement about hypo levels and that they are measured according to plasma glucose levels (which is the point I was making with the quotation from the article). As a result, a meter calibrated to plasma is reflecting fairly on what your glucose levels are in terms of physiological effect on the brain. This is directly relevant to your situation, regardless of the remainder of the topic under discussion in the paper.

Physical hypos effects are a different matter, and if you have been observing hypo sensations at levels that are effectively 12% higher than plasma, that's also normal and no bad thing.

If your concern is loss of hypo symptoms, as long as you are not having many, and deep hypos, it's unlikely that you would lose them. Your target glucose range seems ideally suited for maintaining your pre-warnings.

I think you are worrying untowardly over plasma or whole blood readings, when the research shows hypoglycaemia levels measured according to plasma data. Any value shown as a whole blood value at the same level would therefore show as ~12% lower but still be considered safe, and as plasma level is the important level in terms of hypos, you can "trust" the plasma calibration.

 

[Oldvatr]

When I decided to take back control of my condition some 18 months ago, I was blissfully unaware of the term PE Calibrated. I knew nothing. But I found several posters here that were reporting that their SD Codefree appeared to be reading higher compared to other meters. Since this was something that I too was observing in my own readings, I decided to do research into it,

I found the Accucheck notice on their website about the changes to the strips, but precious little else on this subject. When I looked into the meter manuals etc, the SD stated upfront that it was PE equivalent, but there was nothing in the other meters manuals for them. So I went back to the supplier but they too were unable (and still are to this day) to give me any formal statement in regard to this. I found the Joslin site that mentioned the -12% difference. There was no handy reference to look up and identify which meters were WB or PE, and no indication on NICE or DVLA or DUK of DCUK as to which scaling to apply to the target recommendations, apart from Joslin who have now updated their web info in line with PE.

So, am I trying to control my bgl to meet limits that are 12% lower than they need to be? Does a reading of 10 mmol/l on my meter actually mean 12? Likewise, is a reading of 28 (which I was getting) actually equate to 24 instead? Or are my meters both up the duff? Then I looked at the DVLA guidelines, and being a conscientous driver, I take them seriously even though I am not ID. If my NEO reads below 3.9 but my Codefree reads above 5, then should I get behind the wheel? What if I have an accident, what would the courts think of these 2 readings if it comes to that? My meter's readings take on a legal status that could be used against me in a court of law, so YES It is important to understand where I stand.

I have recently managed to order a replacement to my NEO from Abbott, but I am running short of strips to evaluate it to see if my previous NEO was giving low readings falsely.

I think the hypo problem will resolve soon since my latest research is showing that we may well reach consensus on PE, but so far I have nothing in writing on this, and it comes down to a 'reasonableness' test by me only. Why can no one actually state it with some authority? That is all I ask. I have asked my GP, my DCN, the DCE in the local hospital, I have made enquiries from DVLA, DCUK, DUK, NICE, and the firm that prepared the study that the DVLA guidelines are derived from, and also the firm that wrote the T2D guidelines for NICE. I have now asked 4 pharmacists and raised queries on 2 forums and several different threads.

So far none has been able to answer this simple question, so I am still in the foggy foggy dew-oh. Even the introduction of PE was largely unreported, and something this fundamental to my care should be made clear and not hidden under the carpet.

 

[JohnEGreen]

It makes me think of the off set between magnetic north and true north if you did not calibrate your navigational system to account for that you would end up off course mind you that was true in the old days before GPS and such like not sure if it is still the case the meter may be calibrated for PE but could be programmed to give a reading equivalent to whole blood if it was desired by the manufacturer.

 

[Oldvatr]

It makes me think of the off set between magnetic north and true north if you did not calibrate your navigational system to account for that you would end up off course mind you that was true in the old days before GPS and such like not sure if it is still the case the meter may be calibrated for PE but could be programmed to give a reading equivalent to whole blood if it was desired by the manufacturer.

The secret lies in the strips. Accuchek changed theirs unilaterally but apparently did not warn users about the shift in scaling. I have not used Accuchek for many years now, so I am not sure what warning or advice they give now accompanying their products.

 

[phoenix]

Accu chek flagged it in advance on the internet (and diabetes.uk) It was included in information on the pack inserts. The strips also looked different. https://www.accu-chek.co.uk/gb/news/14april10.html. They were the last on the UK market to change.
But of course people don't necessarily read the information or notice the difference in the strips. http://www.diabetes.co.uk/forum/threads/accu-chek-aviva.17291/

 

[Oldvatr]

The

Accu chek flagged it in advance on the internet (and diabetes.uk) It was included in information on the pack inserts. The strips also looked different. https://www.accu-chek.co.uk/gb/news/14april10.html. They were the last on the UK market to change.
But of course people don't necessarily read the information or notice the difference in the strips. http://www.diabetes.co.uk/forum/threads/accu-chek-aviva.17291/

thread is interesting since it shows our NICE targets were not changed when this was introduced. I see ADA in US has updated their info. but UK seems to be dragging its feet.

Thank you for sharing these nuggets of info. We were here before, and we are here again 8 years later.

 

[Oldvatr]

I have now received a replacement NEO meter from Abbott to compare to my current NEO meter, which is suspected as reading too low for a Plasma meter to ISO (2013). So far I have only done 6 samples, using the same pak of test strips in both meters. If ether of these meters is actually a plasma calibrated meter, then it should only give occasional misreads when compared to an average sample value which includes my 2 declared PE meters.
I attach a graph showing how all 4 meters have compared, and the results show that the new NEO is actually worse than the older meter, and is showing a -36% error which indicates that it is probably not meeting ISO (2013). Since I do not have a YSI Analyser to hand then these results are only indicative, not conclusive, but I do get very good results from my new CareSense Dual meter.

Both Abbott meters are consistently reading lower than my PE meters.

EDIT to Correct: Since doing the graph I have discovered that in fact the large eror shown by the NEO#2 meter was a definite misread, which I have now discounted. In fact the NEO#2 does follow the CaeSense Dual and the largest error seen so far is <10%, so it is still meeting its ISO (2013) spec. The other thing to bear in mind is that when a reading is in hypoland (3,5) then an error of 0.9 mmol.l resolves as a 20% error (of reading) whilst only just being over the 0.83 allowance

 

[Bluetit1802]

How do you know which are errors and which are correct without a lab test at the same time, and are your very good readings from the Caresensor only good because you like them better?

When I do comparison tests the differences are very noticeable but which ones are correct, who knows.

 

[Oldvatr]

I agree it is not conclusive, The best I can do is to take the average of 4 meters that are all supposed to meet the latest ISO standard for accuracy, therefore they should tend to agree with each other certainly over time. The meter manufacturers have relied on us not having access to lab standards, and this is why it has taken me 13 months to establish that at least one of my meters is probably duff/ Unfortunately its replacement seems to be even more duff.

The worst case error between two meters allowed by the ISO is 30%, so a difference od 36% is gross indeed. Certainly below 5.5 mmol/l all 4 meters are required to meet < 0.83mmol/l error absolute. and only 1 meter seems to meet this.

I was myself surprised to find only one meter was better than the others - it is a new attraction, but in fact until I did the graphs today I favoured a different meter, so No, it was not my favourite even though it was the trigger that made me do the evaluation.

 

[Bluetit1802]

The worst case error between two meters allowed by the ISO is 30%, so a difference od 36% is gross indeed. Certainly below 5.5 mmol/l all 4 meters are required to meet < 0.83mmol/l error absolute. and only 1 meter seems to meet this.

This is what I cannot understand. How do you know these meters failed to meet the <0.83 error requirement, and that one of them did meet it?

 

[tim2000s]

The meter manufacturers have relied on us not having access to lab standards, and this is why it has taken me 13 months to establish that at least one of my meters is probably duff

I think you'll find it's more of a case that people don't care. WHen you consider the variation between glucose in arterial, venous, capillary and pulmonary glucose levels, it really doesnt' matter that much. Which of these last four is most important for the brain?

 

[Oldvatr]

This is what I cannot understand. How do you know these meters failed to meet the <0.83 error requirement, and that one of them did meet it?

I go by the method of majority voting in that if 4 meters are certified to fall within a certain band 95% of the time, then I would expect more than one to agree somewhat with the average value obtained from all 4 meters. Yes we can argue the toss on this forever, and it is quite clear neither of us has the means to prove anything. As I stated twice now, my results are indicative only.

Many posters on this Forum have stated that they think their SD Codefree is reading high, and others that the Freestyle strips appear to read low. This is what I have found, and an average of 30 successive samples over a couple of weeks has shown to me that my Codefree is showing an overall bias that is +3.0 mmol/l high. and my original NEO is -3.0 low, as evidenced over 13 months of previous testing, so my recent evaluation confirms what I have also observed over a significant period of testing. The only other possible check that I have made is that the venous blood samples taken by the doctor have in the past come roughly halfway between these two meters (i,e, averaged value as measured in surgery at time of blood test). Again, this is not offered as PROOF, but is indicative that we are at least in a similar ball park. The fact that one meter consistently agrees within 0.83 mmol/l of the averaged value, with only 1 of the 30 samples exceeding this is I think quite significant. I would have expected all of them should have been close if they all met the same standard, with only the occasional misread. By averaging, I am removing some of the jitter and noise.

 

[Oldvatr]

, it really doesnt' matter that much. Which of these last four is most important for the brain?

I need a meter I can trust, Tonight my pre meal on the PE meters was both over 7.2, and both my NEO's are below 5. I am about to drive round the area picking up band members, then driving them to the gig, Then I help unload and set up, before playing our set which normally lasts about 3 hours. Then we do this in reverse and come home.

I have just eaten an LC meal that experience tells me will normally drop my bgl between 2 and 3 points. So I had a slice of bread to keep me rockin'/ So which meters do I use to tell me I',m ok to drive? I have a legal requirement to take reasonable steps. I have a set of meters results for 3 months that show I get technical hypo's, and other meter readings that contradict that, but which would carry more weight in court? When dare I test when playing? When do I stop the set for a reading break? Obviously it would benefit me to use the meters that give a false high value and put my head in the clouds and plead ignorance. Or I can put my head between my knees and kiss it all goodbye.

As I said, I am currently hypo aware, but there is no guarantee that that will continue. If I believe my NEO's then I would treat before I really need to so its safer by default. But next week both NEO;s go in the bin as I am forced to change meter to a new one. So my problem will go away won't it? Then I can stop worrying my head over it, and plead blissful ignorance.

Meanwhile I think there will be others here who are using incorrect limits or are unaware that their meter may be deceiving them. Are they controlling tighter than they need to? Or finding these targets impossible to achieve?
EDIT to add: Well I survived the drive tonight, but the guy in front of ua wrapped his car around some street furniture after sliding on ice. I was able to stop in time. Thankfully it was a dry gig, so I was not breathalysed, and we got home late. No injuries of note.

 

[Oldvatr]

OK I have finally found a definition statement for hypoglycemia being <3.9 mmol/l (<70 mg/dl) based on Plasma scaling.
It is in Wikipedia in the section pasted as follows

Method of measurement (2017)

Blood glucose levels discussed in this article are venous plasma or serum levels measured by standard, automated glucose oxidase methods used in medical laboratories. For clinical purposes, plasma and serum levels are similar enough to be interchangeable. Arterial plasma or serum levels are slightly higher than venous levels, and capillary levels are typically in between.[17] This difference between arterial and venous levels is small in the fasting state but is amplified and can be greater than 10% in the postprandial state.[18] On the other hand, whole blood glucose levels (e.g., by fingerprick meters) are about 10%-15% lower than venous plasma levels.[17] Furthermore, available fingerstick glucose meters are only warranted to be accurate to within 15% of a simultaneous laboratory value under optimal conditions,[citation needed] and home use in the investigation of hypoglycemia is fraught with misleading low numbers.[19][20] In other words, a meter glucose reading of 39 mg/dL could be properly obtained from a person whose laboratory serum glucose was 53 mg/dL; even wider variations can occur with "real world" home use

I was given a clue earlier when it occurred to me that when Joslin (USA) updated their target levels on their website to plasma equivalent, that they did not change the Hypo guidelines values. This adds weight to the Wiki.statement, so I thought a bit further:
My question is - who needs hypo as plasma, and who needs it in whole blood? The definition if Hypo is required by GP's, Hospital staff, Laboratory technicians, the legal profession, and most HCP's. and these all work from venous blood samples as prima facie evidence. It is only users of the older bgl monitors that may have a requirement for WB values. So it makes perfect sense that the definition of clinical hypo was always based on plasma. BUT (see following>)

Further to this, I found a copy of a 2005 wiki text that was the first time they mention plasma values. A previous year text has different values, and no mention of plasma.

Definition from Dec 2004
Research in healthy adults shows that mental efficiency declines measurably as blood glucose falls below 65 mg/dl. Hormonal defense mechanisms (adrenaline and glucagon) are activated as it drops below 55. Furthermore, surveys of children and young adults show that fasting blood glucoses below 60 or above 100 mg/dl are uncommon in the healthy population. On the other hand, individuals vary and not everyone with a blood sugar below 60 will have symptoms, let alone a disease.

Note: 65 mg/d; == 3.6 mmol/l
55 mg/dl == 3.0 mmol/l
So it would seem that the wiki definition of 2004 was probably WB based but this could have been the medical opinion at that time.

I concede on this point, and accept the current definition as being plasma based..

I still have a problem in that I have two meters that read consistently higher than the other two, 3 of these meters are brand new (post 2016) so should meet ISO (2013), but it seems at least 2 are 'faulty'. They are the same model, so it points to a systemic error, not component malfunction.

Edit: I still think the treatment targets as published in the UK are WB based, and lower than the USA plasma levels

 

[Oldvatr]

As some of you are aware, I have recently been mandated by my CCG to select an 'authorised' bgl meter to replace my trusty NEO bgl meter to reduce NHS costs. To this end i have done a short trial with 4 different meters to see which one I should choose for my own use. I will shortly be reporting my findings in the thread 'Has Anuone Used Any of These Meters?' since it is not really relevant to this topic here.

However, the performance of the new meter is different to that of my NEO meter that I had com to trust, and I find that I may still have a problem interpreting the readings wrt hypo's.

I have gone back over the last year's database looking at how my SD Codefree compared to my NEO where I recorded physical symptoms of hypo that I needed to take action over. I can include some events where I had 4 meters monitoring in parallel during the trial/

So, checking my recorded results, my NEO correlated to my symptoms with readings in the range 3,1 to 3,7 mmol.l. The SD Codefree in this period had a range 4.3 to 5.3, and during thr trial period my new Caresense Dual read 4.1 to 4.8. So it seems that my new meter is reading 1 mmol/l higher than my older NEO at this critical point so for me I can expect to be close to hypo when either of my meters reads below 4,9, not 3,9 as per the guidelines. I need to bear this in mind when I am trying to meet DVLA guidelines, or if I start to become less aware of hypo's.

 

[tim2000s]

I need to bear this in mind when I am trying to meet DVLA guidelines, or if I start to become less aware of hypo's.

The DVLA guidelines state that you need to do a "blood test" and not "you need to do a whole blood test" or "you need to do a plasma test". Based on the fact that you feel hypo at around 4-5 on the known plasma meters (which is very typical for most that are not long term insulin users), then there is nothing to think about regarding the DVLA guidelines. Simply five to drive is enough.

So it seems that my new meter is reading 1 mmol/l higher than my older NEO at this critical point so for me I can expect to be close to hypo when either of my meters reads below 4,9, not 3,9 as per the guidelines.

Not really. What you know is when you get symptoms of becoming hypo. Technically, you can only know if your meter is reading you being hypo correctly by comparing it to a properly calibrated lab machine, not by guessing based on how you feel and what a meter with a 0.83mmol/l variance below 4mmol/l, or whatever it is, shows.

OK I have finally found a definition statement for hypoglycemia being <3.9 mmol/l (<70 mg/dl) based on Plasma scaling.

As per this point, made right at the start of this thread.

 

[Oldvatr]

The DVLA guidelines state that you need to do a "blood test" and not "you need to do a whole blood test" or "you need to do a plasma test". Based on the fact that you feel hypo at around 4-5 on the known plasma meters (which is very typical for most that are not long term insulin users), then there is nothing to think about regarding the DVLA guidelines. Simply five to drive is enough.


Not really. What you know is when you get symptoms of becoming hypo. Technically, you can only know if your meter is reading you being hypo correctly by comparing it to a properly calibrated lab machine, not by guessing based on how you feel and what a meter with a 0.83mmol/l variance below 4mmol/l, or whatever it is, shows.


As per this point, made right at the start of this thread.

View attachment 21761

I started this thread, and you are missing the point I am trying to make. I have never had a hypo in the sense that you seem bent on describing, simply because I take steps to avoid getting to that stage Unlike you I am unable to apply dose correction, so I rely on getting warnings so I can take in carbohydrate to raise a low bgl. As a driver, it is important that I react to warnings, and my meters have in the past given me confirmation that my body is reacting to low bgl. Having experienced bgl drops of around 3 mmol.l in one hour due to my meds, I have to have headroom that I can rely on, So I am reliant on my meters to tell me, since my body can be fooled.

My NEO may be a bum steer or whole blood. It does not matter since I was able to trust it. Now I have a meter that seems to read higher at the point where it matters. I have a second meter but it is too erratic and misreading to be relied on. This is my concern, that my meters will give me readings above the magic 5, so I would feel justified in getting behind the wheel. I have had this many times now with my SD meter (PE), and yet it was clear to me that I should not drive without taking action.

I notice that the diagram and the article both show symptoms starting at about 2,9 mmol/l, but my body tells me different to this. Maybe having strokes has made me more sensitive but we are not all the same anyway.