Panel Calls for Lower Gestational Diabetes Cutoffs

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Lower glucose thresholds for gestational diabetes called for by an

international consensus panel may double the number of women diagnosed.

The new criteria require only a single measurement of fasting plasma glucose

of 92 mg/dl or higher or a glucose tolerance test level of at least 180

mg/dl at one hour or 153 mg/dl at two hours.

In high-prevalence countries like the U.S., all pregnant women should

undergo diagnostic 75-g oral glucose tolerance testing, the consensus panel

recommended in the March issue of *Diabetes Care*.

The recommendations are a sharp departure from guidelines in many countries.

Although uniform international standards have been lacking, these levels had

generally been considered safe and in the normal

range<http://www.medpagetoday.com/OBGYN/Pregnancy/9382>during

pregnancy.

The American Diabetes Association recommends risk-based screening only with

a typically two-step process for diagnosis: first a nonfasting glucose

challenge, then a formal glucose tolerance test for confirmation.

ADA diagnostic thresholds are 95 mg/dl for fasting glucose, 180 mg/dl for a

100-mg glucose tolerance test at one hour, and 155 mg/dl at two hours.

Although the difference from the new recommendations is small, the number of

women identified with gestational diabetes will be substantially greater,

said Boyd E. Metzger, MD, of Northwestern University in Chicago, who led the

consensus group.

Under current U.S. guidelines, just 5% to 8% of women receive a gestational

diabetes diagnosis, he noted in an interview.

In the large international Hyperglycemia and Adverse Pregnancy Outcome

(HAPO) trial -- also led by Metzger -- that formed the primary basis for the

group's deliberations, up to 16.1% of pregnant women met at least one of the

criteria.

The new thresholds were set to reflect risk of perinatal harm rather than

the mother's future risk of diabetes or derivation from nonpregnant

populations as has been the case in the past.

The HAPO trial had shown no glucose cutoff

<http://www.medpagetoday.com/MeetingCoverage/ADA/6003>for these risks, so

the panel set their diagnostic criteria at the level at which there was a

75% increased risk compared with the median for:

- Birth weight above the 90th percentile

- Cord C-peptide above the 90th percentile, a marker of the baby's

insulin levels

- Infant percent body fat above the 90th percentile

At these thresholds, the risk was doubled for a large-for-gestational-age

baby, preeclampsia, and toxemia of pregnancy and rose significantly for

cesarean delivery as well, Metzger told *MedPage Today*.

The good news is that trials have shown treating mild gestational

diabetes<http://www.medpagetoday.com/OBGYN/Pregnancy/16227>-- the

majority of cases likely added by the lower glucose criteria --

effectively reduced many of these risks with few women needing anything more

than lifestyle changes, he noted.

However, the proposed guidelines would have to be adopted by organizations

like the American Congress of Obstetricians and Gynecologists to benefit

women and children.

The American Diabetes Association has already started evaluating the

recommendations, although whether it will adopt them remains to be seen,

Metzger said.

One hurdle for adoption may be the increase in costs associated with the

additional diagnoses, cautioned G. Moses, MD, of the South Eastern

Sydney and Illawarra Area Health Service in Wollongong, Australia.

In his editorial in the same issue of *Diabetes Care*, Moses noted that

physicians may actually find the new guidelines more convenient and thus

improve adherence by eliminating the need to get women to return for a

second glucose tolerance test.

*Primary source: *Diabetes Care

Source reference:

Metzger BE, et al " International association of diabetes and pregnancy study

groups recommendations on the diagnosis and classification of hyperglycemia

in pregnancy " * Diabetes Care* 2010; 33: 676-82.

*Additional source:* Diabetes Care

Source reference:

Moses RG " New consensus criteria for GDM: Problem solved or a Pandora's

box? " *Diabetes Care* 2010; 33: 690-91.

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--

Ortiz, MS, RD

Registered Dietitian Day is Wednesday, March 10, 2010

" Nutrition is a Science, Not an Opinion Survey "