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I have noticed a phenomenon....
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<blockquote data-quote="Oldvatr" data-source="post: 2061433" data-attributes="member: 196898"><p>I think I have found a couple of clues to assist in resolving this observation of mine.</p><p></p><p>BGL meters that use test strips actually measure electrical conductivity in the blood sample. The test strip uses an enzyme film that reacts to the presence of glucose by reducing its resistivity, and this is what the meter is calibrated to measure. With no strip inserted, the meter sees very high impedance so switches off. Insertion of the strip into the meter will present a 'known' impedance that the meter can measure and recognise as a valid strip insertion. The meter can also detect a used strip since that has a different resistance, as does a partial misread due to inadequate sample size.</p><p></p><p>So the meter measures the drop in resistance as the enzyme gets converted by the blood sample.</p><p></p><p>But other things in the blood also alter conductivity. We know pure water is a non conductor, but adding impurities such as salt (sodium chloride) will affect the result. This is why we need to wash our fingers before testing since our fingertips do exude sweat (aka salty water) and natural oils too, but can also be contaminated by contact with other impurities such as food.</p><p></p><p>Haematocrit is a measure of how much haemoglobin is present in the blood. Now haemoglobin contains heme iron in small quantities and this is also a conductor. This may explain the sensitivity to haematocrit.</p><p></p><p>But there is another conductor or two in the blood drop that may also be affecting the readings. One of these is sodium, and others are magnesium and potassium, all classed as electrolytes because they conduct charge. The one I noticed recently is sodium since my blood composition recently suffered a severe drop in level to below the danger mark.</p><p></p><p>Unfortunately I was not in nerdy scientist mode. being somewhat ill at the time, so I did not keep records. But I can trace some erratic bgl levels as possibly being correlated to said sodium levels.</p><p>My sodium dropped to 121 mmol/l and my bgl at the time was winging around in the 20's. I was also seeing more than 3 mmol/l difference between my meter readings, where under more sane conditions the difference is usually around 1.2 quite consistently (for me at least).</p><p></p><p>Obviously I took umbrage at this loss of vital substances, and took steps to rectify the situation. I drank Marmite, ate Bovril on Toast, and upped my salt sprinkles. I suffered a dilemma where the GP said stop the diuretics, and the hospital consultant said put them back in. I am on half measures now which is a compromise, but seems to be working.</p><p></p><p>Now as my sodium levels improved, my bgl levels also dropped, Not only that but the difference between them narrowed as well. Then I noticed that if I drank a Marmite before my evening blood sample, then the difference was consistently lower than if I drank a coffee instead. Initially I blamed the lactose in the milk, until I noticed that Marmite is actually quite high in carbs, and should have been giving me higher readings, not lower. Recently my sodium levels tested at 136, which is Normal. My sugars have dropped back down to the 4's and 5's that I had been used to pre op, and the diffference between the meters is less than 0,9 mmol/l so they are tracking much better now,</p><p></p><p>So my theory is that sodium intake may be affecting our meter accuracy, and it may be strip technology dependant too, so different meters will be affected differently. This is an effect that so far is not covered by the ISO tests, and may explain why the SD Codefree is often reported as being reading high.</p><p></p><p>I also wonder about if this plays into the Dawn Phenomenonon that I mentioned in my OP. What if sodium gets filtered out during he night in readiness for the morning pee session, then maybe this is artificially raising the resistance (ie, less conduction) of the blood so we get a morning bump? Just a thought.</p><p></p><p>I need some engineering/ scientific support in this, so I am tagging [USER=496333]@Jim Lahey[/USER] and [USER=209498]@Prem51[/USER] in the hope of extending the research a bit further. Please invite anyone else you know who may be ble to join in this discussion.</p></blockquote><p></p>
[QUOTE="Oldvatr, post: 2061433, member: 196898"] I think I have found a couple of clues to assist in resolving this observation of mine. BGL meters that use test strips actually measure electrical conductivity in the blood sample. The test strip uses an enzyme film that reacts to the presence of glucose by reducing its resistivity, and this is what the meter is calibrated to measure. With no strip inserted, the meter sees very high impedance so switches off. Insertion of the strip into the meter will present a 'known' impedance that the meter can measure and recognise as a valid strip insertion. The meter can also detect a used strip since that has a different resistance, as does a partial misread due to inadequate sample size. So the meter measures the drop in resistance as the enzyme gets converted by the blood sample. But other things in the blood also alter conductivity. We know pure water is a non conductor, but adding impurities such as salt (sodium chloride) will affect the result. This is why we need to wash our fingers before testing since our fingertips do exude sweat (aka salty water) and natural oils too, but can also be contaminated by contact with other impurities such as food. Haematocrit is a measure of how much haemoglobin is present in the blood. Now haemoglobin contains heme iron in small quantities and this is also a conductor. This may explain the sensitivity to haematocrit. But there is another conductor or two in the blood drop that may also be affecting the readings. One of these is sodium, and others are magnesium and potassium, all classed as electrolytes because they conduct charge. The one I noticed recently is sodium since my blood composition recently suffered a severe drop in level to below the danger mark. Unfortunately I was not in nerdy scientist mode. being somewhat ill at the time, so I did not keep records. But I can trace some erratic bgl levels as possibly being correlated to said sodium levels. My sodium dropped to 121 mmol/l and my bgl at the time was winging around in the 20's. I was also seeing more than 3 mmol/l difference between my meter readings, where under more sane conditions the difference is usually around 1.2 quite consistently (for me at least). Obviously I took umbrage at this loss of vital substances, and took steps to rectify the situation. I drank Marmite, ate Bovril on Toast, and upped my salt sprinkles. I suffered a dilemma where the GP said stop the diuretics, and the hospital consultant said put them back in. I am on half measures now which is a compromise, but seems to be working. Now as my sodium levels improved, my bgl levels also dropped, Not only that but the difference between them narrowed as well. Then I noticed that if I drank a Marmite before my evening blood sample, then the difference was consistently lower than if I drank a coffee instead. Initially I blamed the lactose in the milk, until I noticed that Marmite is actually quite high in carbs, and should have been giving me higher readings, not lower. Recently my sodium levels tested at 136, which is Normal. My sugars have dropped back down to the 4's and 5's that I had been used to pre op, and the diffference between the meters is less than 0,9 mmol/l so they are tracking much better now, So my theory is that sodium intake may be affecting our meter accuracy, and it may be strip technology dependant too, so different meters will be affected differently. This is an effect that so far is not covered by the ISO tests, and may explain why the SD Codefree is often reported as being reading high. I also wonder about if this plays into the Dawn Phenomenonon that I mentioned in my OP. What if sodium gets filtered out during he night in readiness for the morning pee session, then maybe this is artificially raising the resistance (ie, less conduction) of the blood so we get a morning bump? Just a thought. I need some engineering/ scientific support in this, so I am tagging [USER=496333]@Jim Lahey[/USER] and [USER=209498]@Prem51[/USER] in the hope of extending the research a bit further. Please invite anyone else you know who may be ble to join in this discussion. [/QUOTE]
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