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Blood glucose numbers - what do they mean?

Quizzy said:
Yes millimoles per mole, thanks. Now I recall my O level chemistry. So that's 42 explained and another dear helper has disentangled HbA1c so my interpretation of H=hydrogen was totally up the creek, though I did realise that A was not arsenic but not that I was in the completely wrong field - it is BIOCHEMISTRY NOT CHEMISTRY!! Forgive me. Hope everyone had a good laugh!
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Nobody was laughing as it was actually a sensible question and I expect clarified it for others.
 
Hi there

Do I have to test sugar levels before and after each meal? New user so not quite sure
 
Hi @amapola and welcome to the forum - if you are testing it is recommended to do so before eating, and then 2hrs afterwards to see the effect that the food (and especially carbohydrates in the food) has had - this page from Diabetes UK explains about testing:

How to check your blood sugar levels

Knowing your blood sugar levels helps you manage your diabetes and reduces your risk of having serious complications – now and in the future. On this page:
www.diabetes.org.uk www.diabetes.org.uk

Hope that helps
 
amapola said:
Hi there

Do I have to test sugar levels before and after each meal? New user so not quite sure
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Only if you want to know how the meal affected your BG levels. Many of us have worked out our diets that way, eg cutting portion sizes or, in a worst case scenario, not having that meal again. Test just before you eat and then 2 hours later. Ideally you should be between 4 and 7 pre-meal and less than 8.5 post-meal, with a difference of less than 3 between the two readings.

Welcome to the forum.
 
amapola said:
Hi there

Do I have to test sugar levels before and after each meal? New user so not quite sure
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Nobody HAS to do anything, but when you test your levels depends upon what you want to gain from testing. If you want to know how your body reacts to different meals then testing just before and 2 hours after eating is the tried and tested way to understand that and adjust your diet in line with the results you get. The thing is that Blood Glucose (BG) goes up and down throughout the day and night in response to approx 42 known factors, food, exercise and medication are the main 3, but lots of other things affect it including stress and alcohol and temperature and hormones. Testing just before eating and 2 hours afterwards kind of isolates the response you have to the food from most of those other factors, so it gives you the clearest view of how your body is responding. You are looking for a rise of less than 3 whole mmols/l between the before and after reading. If you don't take the before reading, then you have no baseline to know how much it rose.
Once you are managing to keep your levels mostly in range, then just testing after meals and keeping the rise to less than 8.5 mmols is often enough but if you are newly diagnosed and your levels are already higher than 8.5 or perhaps even just 7, then you really need to have that baseline reading to be able to see how the meal impacted your levels.

Basically, in between meals your liver is trickling out glucose from it's stores to keep your body ticking over much like a back up battery. If you are stressed, your liver will usually pump out extra glucose, this can be mental/emotional stress or excitement or physical stress like high intensity exercise. If you do low intensity exercise for a decent length of time your muscles will start to suck glucose out of your blood stream to fuel the cells that are using it up. So if I do a fast walk for more than 40 mins my levels will start to drop a bit. That exercise will continue to have a lowering impact on my BG levels for up to 48 hours afterwards as the muscles replace their stores from the glucose in your blood stream. So levels are constantly being pushed up or reduced by different factors and this is why the pre meal test is as important as the post meal test. If you don't test you might be 4.5 before the meal and 8.5 after which is a rise of 4mmols which suggests the meal was too carby for your body to cope. Alternatively you might be 6.5 before the meal and 8.5 2 hours after which means that meal was probably fine for you. Hope that makes sense.
 
Docb said:
Hi @Peter 9611 and welcome to the forum. Just to add to @Leadinglights post.

Newbies are very often confused by the tests and the numbers produced. There are two types of measurement.....

  1. HbA1C. This is the test used for diagnostic purposes but does not measure blood glucose directly. It is a laboratory test done on a sample of blood taken from a vein. If you want to know what it actually measures then google it and get the details. The upshot is the result can be used to take a view on your overall blood glucose control. HbA1c changes slowly and so can be taken at any time with no advanced preparation. The result is usually given in mmol/mol although sometimes it is expressed as a percentage. The interpretation is as above.
  2. Blood glucose measurements. These directly measure the amount of glucose in your blood and is expressed in mmol/l. It is what you get from a hand held meter. Unlike the HbA1C it varies quite a lot in the short term, mostly depending on what you have eaten and how long before the test you ate it. As such, interpretation of the results is not straightforward. It is an excellent test if you are experimenting with diet and want rapid feedback to allow you to make adjustments. T1 diabetics can use them to adjust insulin doses and to cross check readings from continuous monitors.

View attachment 29069


So both tests tell you something about your diabetes and the picture above gives you an idea about how they are related. The blood glucose scale sort of represents the average blood glucose you might get at any given HbA1c.

We often, on the forum, get questions asked about converting the results of spot tests to an HbA1c result. There are ways of going about that but it requires a lot of analysis and for me is one for the nerds. What you can say is that if your Hba1c measurement is high, then this will be reflected in the range you get with spot readings.

So, as a rough rule of thumb, an HbA1c of 48 mmol/mol will result in an average of spot readings of around 8 mmol/l with individual readings ranging from lows around 5 mmol/l to highs around 10 mmol/l.

Hope that helps a bit. Don't worry if it doesn't, you will get the hang of it as time progresses!
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Some what confused with my mmol readings from a libre2. Went to bed on a glass of water no food for 2 hours prior reading 14.7 (yes very high) woke to 17.1 having seen a sharp rise in the hour before waking. What is going on
 
squidds said:
Some what confused with my mmol readings from a libre2. Went to bed on a glass of water no food for 2 hours prior reading 14.7 (yes very high) woke to 17.1 having seen a sharp rise in the hour before waking. What is going on
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Could be Dawn Phenomenon @squidds - a rise in blood sugar prior to getting up.
 
squidds said:
Some what confused with my mmol readings from a libre2. Went to bed on a glass of water no food for 2 hours prior reading 14.7 (yes very high) woke to 17.1 having seen a sharp rise in the hour before waking. What is going on
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The Libre tends not to be very accurate/reliable at higher or very low blood glucose levels so it is wise to check with a finger prick test.
But in the absence of food the liver releases glucose and that can increase blood glucose but in the morning many experience something referred to as Dawn Phenomenon or Foot on the Floor syndrome depending on when that increase happens.
But with just an isolated occurrence is not as easy to figure out.
 
Leadinglights said:
The Libre tends not to be very accurate/reliable at higher or very low blood glucose levels so it is wise to check with a finger prick test.
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Test strips aren't very accurate at those level either, so I think it's better to just treat that kind of reading as "way too high" rather than a number.
 
Leadinglights said:
Exactly the % allowable 'accuracy' is greater the higher the level.
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No it isn’t, it’s the same % isn’t it? Just that 15% of 20 is bigger than 15% of 5
 
Lucyr said:
No it isn’t, it’s the same % isn’t it? Just that 15% of 20 is bigger than 15% of 5
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Probably in this case, though in the quite narrow range (5-8, roughly, if I remember correctly) the percentage is smaller. I wouldn't be shocked to find the 15% is for some range that's not that big.
 
Can I advise a bit of caution when talking about "accuracy"? You can say something about the accuracy of a meter when you use it to test a standard, when you know what the answer should be. Very few of us actually do that, we just use it to test our blood levels.

A much more useful question to ask about a reading is, is it roughly what I might have expected? A second question good question is that posed by @Bruce Stephens - is it way too high and I would add, or way too low? Answering no to the first of those questions or yes to the second might trigger you to take steps to do something about it. Most likely thing it would trigger is to do a retest.

Usual caveat - thinking about T2 not on insulin. T1 is a whole different ball game.
 
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