I've downloaded the
trial and reviewed it:
Women with normal fasting blood sugar and elevated blood sugar
after eating (N=958) were randomly allocated to treatment or usual
care. As one would expect, women were mostly multiparous (75-79%)
and had high BMI (mean 30). To partially mask the control group,
investigators also included 931 women with normal glucose tolerance
matched for race and BMI above or below 27 in the control group.
Their outcomes were not reported, so I am not sure what effect
their inclusion had on the care of control group women.
Treated women were managed according to American Diabetes Assoc.
guidelines and were given insulin if blood sugars were not
normalized. Few women required insulin (8%). The short version of
the ADA recommendations (I obtained the guidelines the
investigators referenced) are essentially a healthy diet and
exercise, and while high BMI women should not be put on a
weight-loss diet, calories can be restricted somewhat to limit
weight gain with monitoring to ensure avoidance of low blood sugar.
No information is given on details of usual care.
No babies were stillborn or died neonatally, and birth trauma
rates were similar, but a much larger study would be needed to
detect differences between groups. Babies in the treatment group
wre less likely to weigh over 4000 g (8 lb 13 oz) (6% vs. 14%) and
to be in the upper 10% of weight for their gestational age (7% vs.
15%) without increasing likelihood of being small for gestational
age--an important point because aggressive sugar control can result
in more undersized babies.
Treated women gained less weight after trial enrollment
(mean 3 kg vs. 5 kg or 6.5 lb vs. 11 lb), had a lower BMI at
delivery (31 vs. 32), and their babies were less likely to
experience shoulder dystocia (head is born but shoulders hang up
behind the pubic bone) (1.5% vs. 4%). Treated women were less
likely to have c/secs both overall (27% vs. 34%) and after
excluding women with conditions unrelated to gestational diabetes
that would increase likelihood of c/sec such as prior c/secs
or abnormal presentation (13% vs. 20%). They were also less
likely to experience pregnancy hypertension (9% vs. 14%) and
preeclampsia (2.5% vs. 5.5%).
What do we learn from this? If you take a group of high-BMI
women, give them a strong motivation to eat right (probably under
the guidance of a registered dietician since these were academic
institutions) and exercise more, and monitor them closely, you will
see the benefits of that compared with when you don't. And if
their obstetricians both believe that treatment works and see
differences that support the belief that the baby will be
deliverable vaginally, such as less weight gain, they will be
less likely to operate. (Lord knows we have enough studies
showing that clinician belief is the primary factor affecting
c/sec rates.) So what's new? I have always maintained that if all
GD screening did was identify women with what should better be
called "carbohydrate intolerance" and helped them with diet and
lifestyle, it would be a good thing, and I would be all for
it. Kudos to these investigators for confirming that. I
maintain, though, first, that they probably could have accomplished
the same thing merely by treating women according to BMI, which
would also have benefited normoglycemic high BMI women, and second,
that a trial carried out in a group of academic institutions does
not reflect the way the typical community ob identifies and treats
GD--and probably not even academic institutions not participating
in a trial of GD treatment--to the detriment of women so