Recurrent gestational diabetes 179

Recurrent gestational diabetes 179

tified for the first time in pregnancy and be classified as GDM. Table 2 Risk Factors for Gestational Diabetes Mellitus and However, if not tested after delivery, a second pregnancy may

Recurrence

be incorrectly classified as recurrent GDM instead of preges- Previous history of gestational diabetes tational DM. These epidemiologic trends suggest that diabe-

Previous diagnosis of GDM before 24 weeks tes, GDM, and recurrent GDM will likely complicate a greater

Insulin requirement in previous pregnancy number of pregnancies in the next few decades.

Previous GDM and weight gain of >15 lbs between In a cross-sectional sample of U.S. adults over the age of 40

pregnancies

tested between 1988 and 1994, 33.8% had an impaired fast- Previous GDM and interval between pregnancies <24 ing glucose (IFG; which is currently defined as a plasma

months

glucose of 100-125 mg/dL after an overnight fast). A total of Previous history of macrosomia (birth weight >9 lbs or

4100 grams)

15.4% had impaired glucose tolerance (IGT), currently de- Previous history of adverse pregnancy outcome (not fined as 140 to 199 mg/dL after a 2-hour oral glucose toler-

clearly attributable to a condition other than diabetes

ance test with 75 g of oral glucose solution. 16 When percent-

during pregnancy)

ages were applied to the entire U.S. population in 2000, an Ethnic group with an elevated risk of gestational and type estimated 41 million adults had prediabetes. Data are not

2 diabetes

readily available for the reproductive age female population

Hispanic

with regard to the prevalence of prediabetes, although in-

African

creasing overweight, obesity, and ethnicity trends suggest

Native American

that a rising prevalence may be occurring.

South or East Asian Pacific Island Ancestry

First degree relative with diabetes

Diagnosis of GDM

Advanced maternal age

Obesity (BMI >30-35 kg/m 2 )

GDM is a condition that lacks international consensus con-

Glucosuria

cerning the method of choice for screening and specific cri-

Metabolic syndrome

teria for diagnosis. The Fourth International Workshop-Con-

Insulin resistance (eg, PCOS)

ference on Gestational Diabetes in 1998 recommended a screening strategy based on risk assessment for detecting ges- tational diabetes and that risk assessment for GDM should be

7 undertaken at the first prenatal visit. are “no data from clinical trials to determine which is superior.” Women can then be Nevertheless, it is important to remember that, similar to other classified as either low-risk, average-risk, or high-risk. High-

screening tests, those for GDM may have problems with repro- risk women should be screened for GDM as soon as feasible

ducibility. 18

during pregnancy. If high-risk women are found not to have As with other high-risk groups, ADA guidelines for the detec- GDM at initial screening, they should be retested between 24

tion of GDM indicate that glucose testing for women with a

history of prior GDM should occur “as soon as feasible,” with linked with GDM include a previous macrosomic infant, obe-

and 28 weeks of gestation. 1 Risk factors most consistently

re-screening, between 24 and 28 weeks if the initial screen is sity, suspected glucose intolerance when not pregnant, glu-

negative. Maser and coworkers 19 evaluated medical records for cosuria, a strong immediate family history of type 2 diabetes

60 women enrolled in a GDM management program that pre- or GDM, history of unexplained fetal demise and, especially,

sented with 2 subsequent pregnancies with GDM to determine women with a history of GDM in a prior pregnancy ( Table 2 ).

whether more specific guidelines for detection are needed. Over

A diagnosis of GDM is based on a positive OGTT (ⱖ2 abnor- half (55%) of these women required insulin during both preg- mal values) most commonly performed after an abnormal

nancies, and 16.7% (10) required insulin during the second 1-hour plasma glucose screen with a 50-g oral glucose load (the

enrollment for GDM, but not the first. For those subjects who “two-step” approach). Diabetes mellitus in pregnancy can also

required insulin during both pregnancies, 88% (29 of 33) were

be diagnosed if the fasting plasma glucose is ⱖ126 mg/dL or a started earlier during the subsequent pregnancy (21.6 ⫾ 8.4 casual plasma glucose is ⱖ200 mg/dL, but these criteria may be

weeks of gestation versus 31.5 ⫾ 2.7 weeks of gestation, P ⬍ less reliable since they are mostly applicable to nonpregnant

0.001). During the subsequent pregnancy, approximately one- adults. Guidelines issued by the Fourth International Workshop

half of the women requiring insulin needed it before 24 weeks,

Conference on Gestational Diabetes Mellitus, 7

the American Di-

whereas a third required it by week 15. Therefore, it seems

abetes Association (ADA-2004), 1

and American College of Ob-

reasonable to perform the initial screen by 15 weeks in women

stetricians and Gynecologists 17

in 2001 lean toward recom-

with a previous history of GDM.

mending the use of the Carpenter-Coustan criteria for the diagnostic 3-hour, 100-g glucose OGTT. However, these orga- nizations also recognize the alternative use of the single-step,

Gestational

2-hour, 75-g glucose OGTT in certain high prevalence popula-

Diabetes Management,

tions (threshold values of 95 mg/dL fasting, 180 mg/dL at 1

General and Recurrent

hour, and 155 mg/dL at 2 hours). ACOG also acknowledges that expert panels have supported both the Carpenter-Coustan and

Despite the debate over screening strategies, there is a clear the National Diabetes Data Group criteria and report that there

association between maternal carbohydrate intolerance and association between maternal carbohydrate intolerance and

tal outcomes. 20 Women with GDM were compared with a cohort of 3637 women with singleton pregnancies that did not have GDM. The study found a direct relationship be- tween OGTT values and multiple adverse outcomes, includ- ing preeclampsia, macrosomia, and operative delivery in

women without frank GDM. Saks and coworkers 21 found a

positive relationship between OGTT results and fetal birth weight in approximately 3500 pregnant women undergoing

screening. Langer and Mazze, 22 in a large prospective study

designed to determine optimal levels of glycemic control for treatment of women with GDM, demonstrated in 246 women with GDM that the women who achieved the lowest range of blood glucose values throughout pregnancy had a significantly lower incidence of LGA and macrosomic in-

fants. In 1994, Langer and coworkers 23 compared intensive

to conventional therapy in 2500 women with GDM. Women in the intensive therapy group had a significantly lower inci- dence of macrosomic and LGA infants. These infants also had lower rates of admission to the neonatal intensive care unit, fewer metabolic complications, and less need for respiratory

support. Langer and coworkers 24 compared 555 gravidas

with GDM diagnosed after 37 weeks with 1110 subjects treated for GDM and 1110 nondiabetic subjects matched from the same delivery year for obesity, parity, ethnicity, and gestational age at delivery. They found a composite adverse outcome rate of 59% for untreated, 18% for treated, and 11% for nondiabetic subjects. A 2- to 4-fold increase in metabolic complications and macrosomia/LGA was found in the un- treated group with no difference between nondiabetic and treated subjects. A 2- to 3-fold higher morbidity rate for the untreated groups was found compared with the other groups. They also concluded that untreated GDM confers significant risks of perinatal morbidity at all disease severity levels.

The Australian Carbohydrate Intolerance Study (ACHOIS) was a large randomized multicenter trial for the treatment of gestational diabetes. 25 The criteria used in this study for the diagnosis of GDM were based on the 75-g OGTT between 24 and 34 weeks gestation. Those with values below 140 mg/dL (7.8 mmol/L) after an overnight fast and between 140 and 198 mg/dL (7.8-11.0 mmol/L) at 2 hours were eligible for randomization. The 490 women assigned to the intervention group had premeal glucose levels below 99 mg/dL and 2- hour postprandial levels that did not exceed 126 mg/dL. The 510 women assigned to the control group received routine care that was consistent with care provided in other facilities in which screening for GDM was not standard. The rate of serious perinatal complications (which was defined as death, shoulder dystocia, bone fracture, and nerve palsy) was sig- nificantly lower among infants of the women in the interven- tion group (self-monitoring of blood glucose levels, individ- ualized medical nutrition therapy counseling and insulin); however, more infants of women in the intervention group

were admitted to the neonatal ICU. Women in the interven- tion group had a higher rate of induction of labor than women in the routine care group, although the rates of ce- sarean delivery were similar at 31% and 32%, respectively. At

3 months postpartum, follow-up data were available for 573 women and revealed lower rates of depression and better quality of life scores, consistent with improved health status in the intervention group.

The above data suggest that making a diagnosis of GDM and identifying effective interventions have the potential to reduce morbidities associated with GDM and improve preg- nancy outcomes. However, it is not clear which management strategies might be most effective for women with recurrent GDM. It seems likely given the probable greater degree of glucose intolerance and onset or diagnosis earlier in gestation that a need for more aggressive use of medications (oral an- tidiabetic agents or insulin) should be anticipated.