Glucose intolerance test

My wife had a glucose intolernace test a few weeks ago and the result
came back negative.

However, because the baby is looking large for dates, the doctor has
sent her for another one (the same 2 hr test).

Just wondering - how accurate is the test in the first instance ? Is
there a possibility that the second one will be positive ?

From what I've read, the oral glucose tolerance test is relatively
unreliable. I "failed" the test and because I have most of the risk
factors for diabetes anyway, I'm going along with the diet and daily
blood glucose testing.

I have the impression that the body's ability to process glucose is
highly variable (what is eaten, how much, in what combination, when,
amount of exercise, the price of rice in China, sunspots, amount of
sleep, whatever), so the OGTT results are sort of a snapshot rather than
a long-running film of what's going on. Your wife could just have
lucked out an had the first test on a "good" day. Alternately, she
could take the second test on a "bad" day.

Also, remember that late term ultrasounds tend to be less accurate about
size estimates.

Gestational diabetes is caused by hormones secreted by the placenta that
reduce the effectiveness of the body's own insulin. This is true of all
pregnant women. The question with GD is, can the body produce enough
insulin to compensate? The further into her pregnancy your wife is (and
the bigger (? more efficient?) her placenta is), the higher chance there
is of her testing positive. Then you have to decide whether you want to
follow the diet and what-all.

Most of the info you'll find in the US plays up the risks and dangers
without really telling you what's going on and why (imagine that!). I
found the chapter on GD in Henci Goer's _Obstetrical Myths vs. Research
Realities_ to be vastly reassuring.

Valerie

paul williams wrote:

My wife had a glucose intolernace test a few weeks ago and the result
came back negative.

However, because the baby is looking large for dates, the doctor has
sent her for another one (the same 2 hr test).

Just wondering - how accurate is the test in the first instance ? Is
there a possibility that the second one will be positive ?

paul williams wrote:

My wife had a glucose intolernace test a few weeks ago and the result
came back negative.

However, because the baby is looking large for dates, the doctor has
sent her for another one (the same 2 hr test).

Just wondering - how accurate is the test in the first instance ? Is
there a possibility that the second one will be positive ?


IIRC, the two hour test is not as inaccurate as
the one hour test (which has lousy reliability), but isn't
the gold standard like the three hour test is.
How far along is your wife? Personally, I'd be very
skeptical about going down this road. Late term ultrasounds
are notoriously bad at estimating birthweight (the margin
of error is generally a good pound and a half either way),
and as soon as they start believing the baby is big it
can put you on the road to all sorts of unnecessary
interventions. Most large babies are born to mothers without
GD and most women with GD have normal sized babies, so
even if the baby really is on the large side, that isn't a
terribly strong indicator of GD. The best predictor of
birthweight is maternal weight plus length of gestation
plus maternal weight gain. And even if she has GD, as
long as she's not diabetic when not pregnant, there's
very little evidence to show that treating GD improves
outcomes anyway.

Best wishes,
Ericka

Ericka Kammerer wrote:

paul williams wrote:

My wife had a glucose intolernace test a few weeks ago and the result
came back negative.

However, because the baby is looking large for dates, the doctor has
sent her for another one (the same 2 hr test).

Just wondering - how accurate is the test in the first instance ? Is
there a possibility that the second one will be positive ?


IIRC, the two hour test is not as inaccurate as
the one hour test (which has lousy reliability), but isn't
the gold standard like the three hour test is.

Though my understanding (mostly from Goer) is that as "gold standards"
go, even the 3-hour test has a fair bit of dross, IYKWIM. Apparently
depends a lot on which set of "ranges" your particular lab uses to
establish a normal reaction.

VSR

How far along is your wife? Personally, I'd be very
skeptical about going down this road. Late term ultrasounds
are notoriously bad at estimating birthweight (the margin
of error is generally a good pound and a half either way),
and as soon as they start believing the baby is big it
can put you on the road to all sorts of unnecessary
interventions. Most large babies are born to mothers without
GD and most women with GD have normal sized babies, so
even if the baby really is on the large side, that isn't a
terribly strong indicator of GD. The best predictor of
birthweight is maternal weight plus length of gestation
plus maternal weight gain. And even if she has GD, as
long as she's not diabetic when not pregnant, there's
very little evidence to show that treating GD improves
outcomes anyway.

Best wishes,
Ericka

paul williams writes:
: My wife had a glucose intolernace test a few weeks ago and the result
: came back negative.

: However, because the baby is looking large for dates, the doctor has
: sent her for another one (the same 2 hr test).

How large for dates? More than 2 weeks? More than 4 weeks?

: Just wondering - how accurate is the test in the first instance ? Is
: there a possibility that the second one will be positive ?

Accurate enough that I would consider the second test both unnecessary
and a bit of scare mongering.

Larry

GTT proved negative for the second time, so no worries there. (as expected).

"Larry McMahan" wrote in message
...
paul williams writes:
: My wife had a glucose intolernace test a few weeks ago and the result
: came back negative.

: However, because the baby is looking large for dates, the doctor has
: sent her for another one (the same 2 hr test).

How large for dates? More than 2 weeks? More than 4 weeks?

: Just wondering - how accurate is the test in the first instance ? Is
: there a possibility that the second one will be positive ?

Accurate enough that I would consider the second test both unnecessary
and a bit of scare mongering.

Larry