# Can I do my own oral glucose tolerance test?



## imac (Apr 12, 2016)

I was diagnosed as pre-diabetes about 18 months ago. I got a FreeStyle Libre in order to see what food causes me grief and what doesn't.

I've cut down on diet, increased exercise and gone from an obese BMI to only an "overweight" BMI, (and hope to go further). Following a fairly unforgiving diet, according to the Freestyle, my A1c is 5.3% or 34. By that measure I don't think I'd even be diagnosed as being a pre-diabetic now.

This weekend, (and I knew that I was being bad), I had two large croissants for breakfast with jam. In one hour, my blood sugar went from 5.8, (fasting level) to 14.4. This suggests that whatever my A1c is, I need to tread very carefully indeed in respect of diet.

Given with a Freestyle I have real time glucose monitoring, would it be possible for me to do my own oral glucose tolerance test and if so, how would I go about doing it?

Thanks in advance.


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## Lindarose (Apr 12, 2016)

I'd be interested to know a bit about glucose tolerance testing. I had one fine whilst pregnant (a lot of years ago) and it was ok. But since diagnosis it's never been suggested. Why is it done? Presumably from the name its to see how your body copes with glucose but what does it show that a BG test doesn't? Who has them apart from pregnant women? If there is a diy one I might have a go if I knew what I'm looking for.


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## FergusC (Apr 12, 2016)

* Pinched from another site:*
*Oral Glucose Tolerance Test *
Diagnosis of type 2 diabetes is often done through either an HbA1c test, or through two consecutive fasting blood capillary tests. This is not always a safe way of testing to see if your blood sugar levels are normal, particularly for those who may already be low-carbing. If results are not convincing, an Oral Glucose Tolerance Test may paint a useful picture. A proper clinical test, following NHS procedures, can easily be self-administered at home following the correct procedure, as described below.

You MUST eat at least 150 grams a day of carbs in the 2 to 3 days leading up to the test.  See the article below from Dr Eades on why youneed to carb up before an OGTT

Buy a 500 ml bottle of ORIGINAL flavour lucozade.

The night before, pour out 394 mls (the amount needed for the test) and leave in a jug to go flat. (makes it easier to drink quickly and put it in the fridge to chill it as this will reduce the sickly sweet taste)

Fast for 12 hours, starting the night before the test. The test itself should be carried out in the morning.

Take a BG reading, and note the reading and the time when it was taken. Official advice is to abandon the test if the pre-test reading is 6.1 mmols or higher, but meaningful results can be obtained even if readings are higher.

Drink the lucozade in 5 minutes, and start testing every 15 minutes if you can afford the strips, or at least every 30 mins if not. Make notes of all your results together with the times when they were taken. Keep testing up to 3 hours after drinking.

During the period of the test, you must eat and drink nothing, and must just sit down. No exercise.

*Analysing the Results*


Official advice is that:-



A reading above 11.1 at the two hour stage is a diagnosis of diabetes.
A reading at that stage between 7.8 and 11.1 is indicative of glucose intolerance – pre diabetes.
A reading below 7.8 at two hours is "normal"

It is stated that individuals can vary, but experience suggests that these figures are too high and interpretation would allow some to go undiagnosed.
Some of those on this forum underwent self-administered OGTT's, and would have been declared either prediabetic or normal as a result of their readings at two hours, even though they were, and still are, fully diagnosed diabetics.
More prudent observations can be made by comparing your readings to those of a true non-diabetic.



Their results are likely to reflect the following:-


At no time would they be likely to exceed a reading of 7.8 mmols.
After 45 minutes, their BGs would be starting to head back to more normal levels.
At the two hour stage, they would be unlikely to be above 5.5 mmols. Indeed, before then, they may experience a low blood sugar episode (perhaps as low as in the 2's)
This is because after fasting and then drinking a sudden influx of glucose, their insulin response would be very quick and very large, and could lead to an over correction of BG.

A reading above 11.1 at ANY TIME during the test is more likely to be indicative of full diabetes.

If you administer a test on yourself, share your results (possible in a nice graph form if it's easier for you, if not just list the times and BG's) with the forum, where experienced members may be able to help you analyse your results.


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## Lindarose (Apr 12, 2016)

Thankyou for your reply Fergus.
 It seems a bit pointless to do it if already diagnosed as type 2 so I don't think Ile bother. But sure it would be useful for some people.


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## AndBreathe (Apr 12, 2016)

imac said:


> I was diagnosed as pre-diabetes about 18 months ago. I got a FreeStyle Libre in order to see what food causes me grief and what doesn't.
> 
> I've cut down on diet, increased exercise and gone from an obese BMI to only an "overweight" BMI, (and hope to go further). Following a fairly unforgiving diet, according to the Freestyle, my A1c is 5.3% or 34. By that measure I don't think I'd even be diagnosed as being a pre-diabetic now.
> 
> ...



I think it's entirely your choice whether you do a home-style OGTT or not, but certainly doing it whilst wearing a Libre sensor would give you an excellent insight into your blood score movements.  I've thought about it and rejected the idea, just from the standpoint of the front end carb loading to ensure my body would be carb adjusted, the I've never really cared for Lucozade, so I haven't done one.

When did you last have a lab HbA1c test done, and what was that score?  I only ask because my own home finger prick testing, and Libre HbA1c estimations are always well adrift of my lab results.  My home tests always suggest a lower result than the lab returns.  For irrelevant reasons, my bloods have been done in 3 different labs, that I know of, and are utterly consistent in the differential, so if you're due a lab test, please try to approach the with an open mind.  Others find, in their own experience, their home and lab tests can be pretty close.

One final point I would make though, is if your croissants were very much out of the ordinary, then your body may have been caught on the hop.  Our bodies like to work to a routine, and that includes how we deal with digestion.  It almost lines up the digestive juices and enzymes it's expecting it will need to deal with your more usual meals.  When you do something extraordinary there can be extraordinary results - and with a big carb hot that can mean extra high readings.

If you wanted to learn more about it, you could ask Dr Google about "Last meal effect blood sugars" or similar.  If you repeated the experiment within a day or two of the first time (in the name of science, obviously  ), you may find the results to be a bit better second time around.  That isn't to say that if you kept doing it, the results would get better every single time.  It's all very personal to your body.

Whatever the answers to these points, well done on trimming up.  That's highly likely to have improved things, it's just a matter of scale.  Well done!


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## FergusC (Apr 12, 2016)

Lindarose said:


> Thankyou for your reply Fergus.
> It seems a bit pointless to do it if already diagnosed as type 2 so I don't think Ile bother. But sure it would be useful for some people.


I found that for me, as a diagnosed T2, by mapping my BG over time, I could check my primary and secondary responses.
(M primary response is shot, I peak @ ~50 min at ~10.5 from fasting of ~5.0, and my secondary response is strong enough that @ 120 min I am at ~4.1 before rising slightly to~4.6 by 180 minutes)


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## Lindy77 (Aug 28, 2017)

FergusC said:


> * Pinched from another site:*
> *Oral Glucose Tolerance Test *
> Diagnosis of type 2 diabetes is often done through either an HbA1c test, or through two consecutive fasting blood capillary tests. This is not always a safe way of testing to see if your blood sugar levels are normal, particularly for those who may already be low-carbing. If results are not convincing, an Oral Glucose Tolerance Test may paint a useful picture. A proper clinical test, following NHS procedures, can easily be self-administered at home following the correct procedure, as described below.
> 
> ...




I have completed a glucose tolerance test at home. 

Here are my figures
Fasting blood. 6.5
Half hour later 14.1
One hour later 14.4
One and half hour later 15.3
Two hours later 15.4


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## Ljc (Aug 28, 2017)

Hi @Lindy77 Welcome.  Feel free to ask questions.  What did your test show.


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## Lindy77 (Aug 28, 2017)

Ljc said:


> Hi @Lindy77 Welcome.  Feel free to ask questions.  What did your test show.




My test results are as follows

Fasting 6.5
Half hour reading 14.1
One hour reading 14.4
One and half hour reading 15.3
Two hours reading 15.4


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## Ljc (Aug 28, 2017)

Hi again. They do seem rather high, did you fast for 12 hrs and wash your hands before each test. 
I am assuming that you have not been diagnosed but do have some symptoms ?  The best thing for you to do now is arrange an appointment with gp , so s/he can arrange blood tests. 
The sooner you have a diagnosis the better.


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