Confused about Blood Tests

[Nexus6]

Hello all,

Background - I am possibly in the pre-diabetes diagnosis area based on some previous random blood tests, and my doctor prescribed a follow up fasting test as well as adding a glucose tolerance test. Didn't include another A1C though.

After that initial diagnosis and finding this site, I have since gone pretty strict LCHF for the last couple months and done some intermittent fasting etc. Have since lost about 25 pounds (down to 200lbs). I also purchased a glucose meter and started testing (probably waaaaay too much) to determine trigger foods, patterns etc. One thing I noticed from testing (and this still continues) is that I definitely suffer from dawn/morning syndrome and or stress/hormone related glucose rises.

When I wake (and for the next couple hours) my glucose is almost always anywhere from 5.5 to 6.5. It also reads these levels when I am stressed etc. But, after relaxing, or 2-3 hours after waking (while remaining in a fasted state), my glucose will always drop back down to 4.3 - 4.6.

Problem is, I am still confused with is WHEN (what time of day) to go for my follow-up blood tests. Do I want to schedule the test for 8:00am, so the doctor sees the higher morning levels (and then explain to him afterwards my testing and dawn syndrome etc), or do I want to ignore the dawn syndrome numbers, and schedule my exam for around 11:00am (still fasted) where my glucose readings will be much lower (and then explain to him I also have higher waking reading?)

I've been tracking all my readings in the app with the meter so will provide him a longer term chart as well.

Note...since going LCHF, my A1C has dropped from close to 6% down to 5.1% in 2 months, so I will continue along that path (though my Dr's recommendation is the Canadian Diabetes diet, which is low fat, and much higher carbs).

Important...I am NOT trying to avoid any sort of diagnosis one way or the other...I am pretty sure I will "flunk" to the GTT test as from my testing, I always get a significant rise in glucose after ingesting even moderate amounts of carbs. Will be interest to see what happens after a GTT test. Is there any way to "simulate" that at home? I've seen some mention 15 teaspoons of sugar is somewhat similar.

Thanks all....

 

[Alison Campbell]

Well done for getting your numbers down, If you are having a GTT you need to carb up prior to the test to give comparable results. I have seen it recommended in low carb circles for people to eat at least 150g per day for 3 days before the test to allow the body to be prepared and produce normal levels of insulin to deal with the glucose challenge.

You can usually purchase the solution from medical suppliers that hospitals use for the test. A number of experienced members did home GTT and compared their results on the forum. I think @CherryAA collected and interpreted the results.

I would not be so concered about timing and fasting levels, when you HBA1C has improved so much. My priority would be to get the most realistic GTT as if you were eating normally.

Saying that I refused to have a second GTT as the first one I had was very uncomfortable.

 

[Bluetit1802]

Many doctors use Rapilose for the OGTT. The instructions on this (a drink of 75g of pure glucose) say:

The 75g Oral Glucose Tolerance Test (OGTT) is a relatively simple test, however, the following protocol should be complied with. The test is usually carried out to establish diabetes mellitus or impaired glucose tolerance when the fasting venous plasma glucose is <7.0mmol/l.

1. Patient Preparation The test should only be carried out on patients who are on a stable diet, at a constant weight and with no acute illness. The patient should have maintained an adequate carbohydrate intake (125- 150g/day) for three days prior to the scheduled OGTT.
The patient is required to fast overnight before the test for a minimum nine hours with nothing by mouth except water (no medications, caffeine or tobacco).
Other factors can weaken the diagnostic power of the test and should be avoided as far as possible. These include severe inactivity over the preceding weeks, bed rest for several days, medical or surgical stress, fear of venepuncture, smoking during the test and certain drugs including thiazides, ß-blockers, glucocorticoids and phenytoin.

http://penlanhealthcare.com/uploads/Rapilose-OGTT-Instructions-For-Use.pdf

The reason for the 150g carbs for 3 days beforehand is because if you are on a low carb diet of much less than this your pancreas will be used to producing insulin according to the amount of carbs it is expecting. If you then hit it with 75g pure glucose it may not produce an adequate amount of insulin to cover that glucose and you are very likely to fail the test.

The fasting test will just be to get a base line for the OGTT.

I bought a bottle of the Rapilose and did a test at home.

 

[Deleted member 308541]

Problem is, I am still confused with is WHEN (what time of day) to go for my follow-up blood tests.

I had a fasting blood test done yesterday morning at the pathology shop at the private hospital near me.

I always go around the 7:15 am time as the first rush of workers getting tested have started to go through. One women was into the bottle of glucose drink after she had the initial blood sample taken.

The blood taken is venous, not capillary, so the liver dump / dawn phenomenon should not effect the results.

 

[Bluetit1802]

The blood taken is venous, not capillary, so the liver dump / dawn phenomenon should not effect the results.

Oh but it will! On a fasting plasma glucose test, if the liver has dumped and the insulin hasn't done its job, the glucose will be in the blood stream and will be picked up. It won't affect the HbA1c but it will affect the Fasting plasma test.

 

[Deleted member 308541]

It won't affect the HbA1c but it will affect the Fasting plasma test.

You are most probably right on that.

I do not worry about LD /DP when I go for a fasting blood test, I am more concerned about getting black coffee and breakfast into me as soon as I have had my blood taken.

 

[Nexus6]

You are most probably right on that.

I do not worry about LD /DP when I go for a fasting blood test, I am more concerned about getting black coffee and breakfast into me as soon as I have had my blood taken.

Hehe...I hear you. Since dropping carbs from my diet, I can now easily fast all day if I choose to so the timing doesn't really matter to me in relation to hunger etc.

For the last few days, I've purposely fasted until 11:00am (except water) and can consistently map my glucose like this....

Wake up (7:00am) take shower, take blood glucose (almost always right around 6.0), drive to work for 8:00am and take blood glucose around 8:30am (always around 6.5), sit at desk and get to work (sip water) and around 11:00am take glucose reading - usually between 4.5 and 5.0). Every single day....like clockwork.

 

[Alison Campbell]

Hi @misha52, what type of diabetes do you have and are you taking any medications for diabetes?