Point/Counterpoint – Should the IADPSG criteria for diagnosing gestational diabetes be adopted now worldwide?

POINT: Preventing adverse outcomes in newborns is imperative.

In March 2013, an independent panel at a National Institutes of Health consensus development conference recommended against adopting the one-step approach to diagnosis of gestational diabetes mellitus (GDM) that was recommended in 2008 by the International Association of Diabetes and Pregnancy Study Groups (IADPSG) and adopted by the American Diabetes Association, the World Health Organization, and organizations in other countries. The NIH panel voiced concerns about costs and interventions that would accompany an increased prevalence of GDM, as well as uncertainties about the benefits of identifying and treating so many additional new cases of GDM.

The panel’s recommendation is inconsistent with available data. There is more than sufficient evidence that the one-step approach should be used worldwide – without waiting for more research.

The study on which the IADPSG criteria were based – the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Study (N. Engl. J. Med. 2008;358:1991-2002) – involved more than 23,000 pregnancies in nine different countries. All of the adverse pregnancy outcomes evaluated were related directly and significantly, and in a continuous fashion, to glucose concentrations at the fasting, 1-hour, and 2-hour points in a single 75-g, 2-hour oral glucose tolerance test (OGTT).

The IADPSG recommended that GDM be diagnosed when one or more of the plasma glucose values were met or exceeded: fasting, 92 mg/dL; 1-hour, 180 mg/dL; 2-hour, 153 mg/dL. According to the HAPO study data, patients with GDM have an approximate doubling of the likelihood of a birth weight above the 90th percentile compared to those without GDM, as well as a near-tripling of the likelihood of fetal hyperinsulinemia, twice the likelihood of preeclampsia, and a 50% increase in primary cesarean section, among other increased complication rates (Diabetes Care 2010;33:676-82).

The IADPSG diagnostic criteria are based on a predictive value of a 1.75 odds ratio above the mean for large for gestational age (LGA), neonatal body fat greater than 90th percentile, and cord blood hyperinsulinemia. This is equivalent to a doubling in the likelihood of these outcomes, because the 1.75 odds ratio is compared to the mean rather than to everyone without GDM.

HAPO was indeed an observational study, but we have solid data from other randomized trials demonstrating that intervention for mild GDM will prevent excess adverse outcomes.

In one of two recent randomized single-blinded trials on identifying and treating GDM, mild GDM was defined as a 2-hour, 75-g OGTT value between 140 and 198 mg/dL with a fasting plasma glucose value less than 140 mg/dL (mean, 86 mg/dL) – diagnostic criteria that, if anything, are lower than the IADPSG criteria. Patients randomized for intervention had a 66% reduction in "serious complications." Macrosomia was reduced by 50%, and preeclampsia by 30%. The cesarean rate was unchanged between the 1,000 women in the intervention and routine care groups (N. Engl. J. Med. 2005:352:2477-8).

In the second study of 958 women, identification and treatment lowered by half the rates of macrosomia, preeclampsia, and shoulder dystocia. There were other significant reductions in complications, and no difference in the rate of small-for-gestational-age infants (N. Engl. J. Med. 2009;361:1339-48). The criteria used to define mild GDM in this study meet the lower of two alternative sets of criteria recommended by the American College of Obstetricians and Gynecologists, but with a normal fasting plasma glucose concentration of 95 mg/dL or less.

Critics of the recommendations in the United States who say it is unreasonable and too expensive for such a large proportion of pregnant women to be identified as having a disease – 16%-18% in the HAPO population – need to look at the big picture.

Among women in the United States aged 18-44 years, 5% had diabetes and 26% had prediabetes from 2005 to 2008. Why, then, is 16%-18% called outrageously high, when the rate of prediabetes/diabetes outside of pregnancy is almost twice as high?

Undoubtedly, an increase in the number of mild GDM cases will increase costs – just as the broader epidemic of diabetes and prediabetes is increasing health care costs. Cost and resource issues are insufficient reasons, however, not to identify high-risk pregnancies in which adverse outcomes can be prevented with relatively simple interventions.

Indeed, we must develop more efficient ways to care for patients with GDM, but this is within our reach. We know from the trials of identifying and treating mild GDM that diet treatment is largely effective; only 8% and 20% women in these studies required insulin. This is reassuring. Group patient education may be helpful, and we have evidence that less frequent glucose monitoring – every second or third day, rather than daily – may be feasible.

We also must improve our level of postdelivery care; a cost-effectiveness analysis of the IADPSG criteria demonstrated that the new one-step approach will not be cost-effective without it. This is not surprising. Moreover, it’s a logical imperative: In addition to preventing adverse outcomes in newborns, an important benefit of diagnosing GDM is the opportunity to prevent diabetes in the future.

Dr. Coustan is professor of obstetrics and gynecology at the Warren Alpert Medical School of Brown University in Providence, R.I.

COUNTERPOINT: Not yet.

Diagnosing GDM with a single-step approach – rather than a two-step approach – is a positive change. The problem lies not with the one-step 75-g OGTT, but largely with the new diagnostic threshold values for GDM proposed by the IADPSG as part of this new one-step approach.

The HAPO study – the international observational study on which the IADPSG based its recommendations – was a beautiful study. It provided valuable data on the relationship between OGTT values and adverse perinatal outcomes. Unfortunately, but not surprisingly, there was a continuous linear relationship among fasting, 1-hour, and 2-hour glucose values and the frequency of adverse outcomes.

With this linear relationship and no clear-cut off values for normal and abnormal test results, the threshold values are by definition arbitrary. The IADPSG chose to base its diagnostic thresholds on a 1.75-fold increase in the incidence of fetal macrosomia. Using these criteria, approximately 18% of pregnant women worldwide, and 17%-25% of pregnant women in the United States, would be diagnosed as having GDM.

At the current time, there is insufficient evidence that the benefits of such an enormous increase in GDM patients would outweigh the disadvantages.

Two randomized studies have shown that treatment of GDM improves outcomes – lowering the incidence of fetal macrosomia, mortality, birth trauma, and in one study, cesarean delivery – but we do not have strong evidence yet that diagnosing and treating minor glucose abnormalities in all women will significantly improve outcomes.

There also is a real risk of "overmedicalization." A recent article that details driving factors – technological changes detecting even smaller abnormalities, for instance, and conflicted panels writing expanded disease definitions (BMJ 2012;344:e3502) – is acutely applicable to GDM. With lower thresholds, we run the risk of overdiagnosis, which could result in increases in labor inductions and in elective and secondary cesarean deliveries – without proven benefit.

This is starting to happen in Belgium: Data that are as yet unpublished in the medical literature show that the number of labor inductions in women with GDM – women whose diagnoses were made using lower thresholds than previously employed – has been rising. The interventions are driven by concern about presumed large babies, but thus far, signs are lacking of adverse effects in the babies.

With respect to prevention of childhood obesity, we need to consider the fact that while GDM is related to obesity in the offspring, this appears to be mainly in the case of coexisting maternal obesity.

A study from Finland showed that overweight and abdominal obesity in adolescents was associated with maternal obesity, and even more so with the combination of obesity and GDM, but not with GDM itself (Diabetes Care 2010:33;1115-21). Similar U.S. data on childhood metabolic syndrome have been published (Pediatrics 2005:115;e290-6), and a recent meta-analysis has shown that the relationship between diabetes in pregnancy and childhood obesity disappeared after adjustment for maternal BMI (Diabetologia 2011;54:1957-66).

We know from HAPO data too that GDM and obesity are independent risk factors with synergistic effects on short-term outcomes such as preeclampsia, primary cesarean deliveries, macrosomia, increased cord C-peptide levels, and newborn body fat.

As my colleague Dr. Harold W. de Valk and I point out in a recent article, it might be best to use stricter diagnostic thresholds for obese women rather than for all women, given what we know thus far about these synergistic effects and the possibility of a larger effect of obesity on long-term development of offspring (Am. J. Obstet. Gynecol. 2013:208;260-4).

This principle is part and parcel of the so-called Ryan recommendations, which may provide a more sensible alternative to the IADPSG approach. Dr. Ryan proposes that we use a threshold based on a twofold increase in large for gestational age (for an overall incidence of GDM around 10% instead of 18%), that we consider evidence insufficient for the treatment of very mild increases of glucose, except for increases in obese women, and that we continue to collect data and study outcomes (Diabetologia 2011;54:480-6).

A randomized controlled trial stratified for maternal BMI, in which half of the women with OGTT results in between the two proposed diagnostic threshold values are treated, is mandatory.

Dr. de Valk and I have reviewed the published arguments for and against changing the diagnostic criteria for GDM now, and we have other concerns, including the timing and poor reproducibility of the OGTT, the reliance on large for gestational age as an endpoint for setting diagnostic criteria, and the increase in use of oral antidiabetic drugs that could result from a vast increase in GDM.

Overall, we agree with the National Institutes of Health panel that real evidence for change is lacking, and that there is a lot to be done before we significantly expand GDM.

Dr. Visser is professor of obstetrics and gynecology at University Medical Center in Utrecht, the Netherlands.

Based on presentations made at the annual meeting of the Diabetes in Pregnancy Study Group of North America, Washington. Both Dr. Coustan and Dr. Visser reported that they had no conflicts of interest to disclose.

POINT: Preventing adverse outcomes in newborns is imperative.

In March 2013, an independent panel at a National Institutes of Health consensus development conference recommended against adopting the one-step approach to diagnosis of gestational diabetes mellitus (GDM) that was recommended in 2008 by the International Association of Diabetes and Pregnancy Study Groups (IADPSG) and adopted by the American Diabetes Association, the World Health Organization, and organizations in other countries. The NIH panel voiced concerns about costs and interventions that would accompany an increased prevalence of GDM, as well as uncertainties about the benefits of identifying and treating so many additional new cases of GDM.

The panel’s recommendation is inconsistent with available data. There is more than sufficient evidence that the one-step approach should be used worldwide – without waiting for more research.

The study on which the IADPSG criteria were based – the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Study (N. Engl. J. Med. 2008;358:1991-2002) – involved more than 23,000 pregnancies in nine different countries. All of the adverse pregnancy outcomes evaluated were related directly and significantly, and in a continuous fashion, to glucose concentrations at the fasting, 1-hour, and 2-hour points in a single 75-g, 2-hour oral glucose tolerance test (OGTT).

The IADPSG recommended that GDM be diagnosed when one or more of the plasma glucose values were met or exceeded: fasting, 92 mg/dL; 1-hour, 180 mg/dL; 2-hour, 153 mg/dL. According to the HAPO study data, patients with GDM have an approximate doubling of the likelihood of a birth weight above the 90th percentile compared to those without GDM, as well as a near-tripling of the likelihood of fetal hyperinsulinemia, twice the likelihood of preeclampsia, and a 50% increase in primary cesarean section, among other increased complication rates (Diabetes Care 2010;33:676-82).

The IADPSG diagnostic criteria are based on a predictive value of a 1.75 odds ratio above the mean for large for gestational age (LGA), neonatal body fat greater than 90th percentile, and cord blood hyperinsulinemia. This is equivalent to a doubling in the likelihood of these outcomes, because the 1.75 odds ratio is compared to the mean rather than to everyone without GDM.

HAPO was indeed an observational study, but we have solid data from other randomized trials demonstrating that intervention for mild GDM will prevent excess adverse outcomes.

In one of two recent randomized single-blinded trials on identifying and treating GDM, mild GDM was defined as a 2-hour, 75-g OGTT value between 140 and 198 mg/dL with a fasting plasma glucose value less than 140 mg/dL (mean, 86 mg/dL) – diagnostic criteria that, if anything, are lower than the IADPSG criteria. Patients randomized for intervention had a 66% reduction in "serious complications." Macrosomia was reduced by 50%, and preeclampsia by 30%. The cesarean rate was unchanged between the 1,000 women in the intervention and routine care groups (N. Engl. J. Med. 2005:352:2477-8).

In the second study of 958 women, identification and treatment lowered by half the rates of macrosomia, preeclampsia, and shoulder dystocia. There were other significant reductions in complications, and no difference in the rate of small-for-gestational-age infants (N. Engl. J. Med. 2009;361:1339-48). The criteria used to define mild GDM in this study meet the lower of two alternative sets of criteria recommended by the American College of Obstetricians and Gynecologists, but with a normal fasting plasma glucose concentration of 95 mg/dL or less.

Critics of the recommendations in the United States who say it is unreasonable and too expensive for such a large proportion of pregnant women to be identified as having a disease – 16%-18% in the HAPO population – need to look at the big picture.

Among women in the United States aged 18-44 years, 5% had diabetes and 26% had prediabetes from 2005 to 2008. Why, then, is 16%-18% called outrageously high, when the rate of prediabetes/diabetes outside of pregnancy is almost twice as high?

Undoubtedly, an increase in the number of mild GDM cases will increase costs – just as the broader epidemic of diabetes and prediabetes is increasing health care costs. Cost and resource issues are insufficient reasons, however, not to identify high-risk pregnancies in which adverse outcomes can be prevented with relatively simple interventions.

Indeed, we must develop more efficient ways to care for patients with GDM, but this is within our reach. We know from the trials of identifying and treating mild GDM that diet treatment is largely effective; only 8% and 20% women in these studies required insulin. This is reassuring. Group patient education may be helpful, and we have evidence that less frequent glucose monitoring – every second or third day, rather than daily – may be feasible.

We also must improve our level of postdelivery care; a cost-effectiveness analysis of the IADPSG criteria demonstrated that the new one-step approach will not be cost-effective without it. This is not surprising. Moreover, it’s a logical imperative: In addition to preventing adverse outcomes in newborns, an important benefit of diagnosing GDM is the opportunity to prevent diabetes in the future.

Dr. Coustan is professor of obstetrics and gynecology at the Warren Alpert Medical School of Brown University in Providence, R.I.

COUNTERPOINT: Not yet.

Diagnosing GDM with a single-step approach – rather than a two-step approach – is a positive change. The problem lies not with the one-step 75-g OGTT, but largely with the new diagnostic threshold values for GDM proposed by the IADPSG as part of this new one-step approach.

The HAPO study – the international observational study on which the IADPSG based its recommendations – was a beautiful study. It provided valuable data on the relationship between OGTT values and adverse perinatal outcomes. Unfortunately, but not surprisingly, there was a continuous linear relationship among fasting, 1-hour, and 2-hour glucose values and the frequency of adverse outcomes.

With this linear relationship and no clear-cut off values for normal and abnormal test results, the threshold values are by definition arbitrary. The IADPSG chose to base its diagnostic thresholds on a 1.75-fold increase in the incidence of fetal macrosomia. Using these criteria, approximately 18% of pregnant women worldwide, and 17%-25% of pregnant women in the United States, would be diagnosed as having GDM.

At the current time, there is insufficient evidence that the benefits of such an enormous increase in GDM patients would outweigh the disadvantages.

Two randomized studies have shown that treatment of GDM improves outcomes – lowering the incidence of fetal macrosomia, mortality, birth trauma, and in one study, cesarean delivery – but we do not have strong evidence yet that diagnosing and treating minor glucose abnormalities in all women will significantly improve outcomes.

There also is a real risk of "overmedicalization." A recent article that details driving factors – technological changes detecting even smaller abnormalities, for instance, and conflicted panels writing expanded disease definitions (BMJ 2012;344:e3502) – is acutely applicable to GDM. With lower thresholds, we run the risk of overdiagnosis, which could result in increases in labor inductions and in elective and secondary cesarean deliveries – without proven benefit.

This is starting to happen in Belgium: Data that are as yet unpublished in the medical literature show that the number of labor inductions in women with GDM – women whose diagnoses were made using lower thresholds than previously employed – has been rising. The interventions are driven by concern about presumed large babies, but thus far, signs are lacking of adverse effects in the babies.

With respect to prevention of childhood obesity, we need to consider the fact that while GDM is related to obesity in the offspring, this appears to be mainly in the case of coexisting maternal obesity.

A study from Finland showed that overweight and abdominal obesity in adolescents was associated with maternal obesity, and even more so with the combination of obesity and GDM, but not with GDM itself (Diabetes Care 2010:33;1115-21). Similar U.S. data on childhood metabolic syndrome have been published (Pediatrics 2005:115;e290-6), and a recent meta-analysis has shown that the relationship between diabetes in pregnancy and childhood obesity disappeared after adjustment for maternal BMI (Diabetologia 2011;54:1957-66).

We know from HAPO data too that GDM and obesity are independent risk factors with synergistic effects on short-term outcomes such as preeclampsia, primary cesarean deliveries, macrosomia, increased cord C-peptide levels, and newborn body fat.

As my colleague Dr. Harold W. de Valk and I point out in a recent article, it might be best to use stricter diagnostic thresholds for obese women rather than for all women, given what we know thus far about these synergistic effects and the possibility of a larger effect of obesity on long-term development of offspring (Am. J. Obstet. Gynecol. 2013:208;260-4).

This principle is part and parcel of the so-called Ryan recommendations, which may provide a more sensible alternative to the IADPSG approach. Dr. Ryan proposes that we use a threshold based on a twofold increase in large for gestational age (for an overall incidence of GDM around 10% instead of 18%), that we consider evidence insufficient for the treatment of very mild increases of glucose, except for increases in obese women, and that we continue to collect data and study outcomes (Diabetologia 2011;54:480-6).

A randomized controlled trial stratified for maternal BMI, in which half of the women with OGTT results in between the two proposed diagnostic threshold values are treated, is mandatory.

Dr. de Valk and I have reviewed the published arguments for and against changing the diagnostic criteria for GDM now, and we have other concerns, including the timing and poor reproducibility of the OGTT, the reliance on large for gestational age as an endpoint for setting diagnostic criteria, and the increase in use of oral antidiabetic drugs that could result from a vast increase in GDM.

Overall, we agree with the National Institutes of Health panel that real evidence for change is lacking, and that there is a lot to be done before we significantly expand GDM.

Dr. Visser is professor of obstetrics and gynecology at University Medical Center in Utrecht, the Netherlands.

Based on presentations made at the annual meeting of the Diabetes in Pregnancy Study Group of North America, Washington. Both Dr. Coustan and Dr. Visser reported that they had no conflicts of interest to disclose.

POINT: Preventing adverse outcomes in newborns is imperative.

In March 2013, an independent panel at a National Institutes of Health consensus development conference recommended against adopting the one-step approach to diagnosis of gestational diabetes mellitus (GDM) that was recommended in 2008 by the International Association of Diabetes and Pregnancy Study Groups (IADPSG) and adopted by the American Diabetes Association, the World Health Organization, and organizations in other countries. The NIH panel voiced concerns about costs and interventions that would accompany an increased prevalence of GDM, as well as uncertainties about the benefits of identifying and treating so many additional new cases of GDM.

The panel’s recommendation is inconsistent with available data. There is more than sufficient evidence that the one-step approach should be used worldwide – without waiting for more research.

The study on which the IADPSG criteria were based – the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Study (N. Engl. J. Med. 2008;358:1991-2002) – involved more than 23,000 pregnancies in nine different countries. All of the adverse pregnancy outcomes evaluated were related directly and significantly, and in a continuous fashion, to glucose concentrations at the fasting, 1-hour, and 2-hour points in a single 75-g, 2-hour oral glucose tolerance test (OGTT).

The IADPSG recommended that GDM be diagnosed when one or more of the plasma glucose values were met or exceeded: fasting, 92 mg/dL; 1-hour, 180 mg/dL; 2-hour, 153 mg/dL. According to the HAPO study data, patients with GDM have an approximate doubling of the likelihood of a birth weight above the 90th percentile compared to those without GDM, as well as a near-tripling of the likelihood of fetal hyperinsulinemia, twice the likelihood of preeclampsia, and a 50% increase in primary cesarean section, among other increased complication rates (Diabetes Care 2010;33:676-82).

The IADPSG diagnostic criteria are based on a predictive value of a 1.75 odds ratio above the mean for large for gestational age (LGA), neonatal body fat greater than 90th percentile, and cord blood hyperinsulinemia. This is equivalent to a doubling in the likelihood of these outcomes, because the 1.75 odds ratio is compared to the mean rather than to everyone without GDM.

HAPO was indeed an observational study, but we have solid data from other randomized trials demonstrating that intervention for mild GDM will prevent excess adverse outcomes.

In one of two recent randomized single-blinded trials on identifying and treating GDM, mild GDM was defined as a 2-hour, 75-g OGTT value between 140 and 198 mg/dL with a fasting plasma glucose value less than 140 mg/dL (mean, 86 mg/dL) – diagnostic criteria that, if anything, are lower than the IADPSG criteria. Patients randomized for intervention had a 66% reduction in "serious complications." Macrosomia was reduced by 50%, and preeclampsia by 30%. The cesarean rate was unchanged between the 1,000 women in the intervention and routine care groups (N. Engl. J. Med. 2005:352:2477-8).

In the second study of 958 women, identification and treatment lowered by half the rates of macrosomia, preeclampsia, and shoulder dystocia. There were other significant reductions in complications, and no difference in the rate of small-for-gestational-age infants (N. Engl. J. Med. 2009;361:1339-48). The criteria used to define mild GDM in this study meet the lower of two alternative sets of criteria recommended by the American College of Obstetricians and Gynecologists, but with a normal fasting plasma glucose concentration of 95 mg/dL or less.

Critics of the recommendations in the United States who say it is unreasonable and too expensive for such a large proportion of pregnant women to be identified as having a disease – 16%-18% in the HAPO population – need to look at the big picture.

Among women in the United States aged 18-44 years, 5% had diabetes and 26% had prediabetes from 2005 to 2008. Why, then, is 16%-18% called outrageously high, when the rate of prediabetes/diabetes outside of pregnancy is almost twice as high?

Undoubtedly, an increase in the number of mild GDM cases will increase costs – just as the broader epidemic of diabetes and prediabetes is increasing health care costs. Cost and resource issues are insufficient reasons, however, not to identify high-risk pregnancies in which adverse outcomes can be prevented with relatively simple interventions.

Indeed, we must develop more efficient ways to care for patients with GDM, but this is within our reach. We know from the trials of identifying and treating mild GDM that diet treatment is largely effective; only 8% and 20% women in these studies required insulin. This is reassuring. Group patient education may be helpful, and we have evidence that less frequent glucose monitoring – every second or third day, rather than daily – may be feasible.

We also must improve our level of postdelivery care; a cost-effectiveness analysis of the IADPSG criteria demonstrated that the new one-step approach will not be cost-effective without it. This is not surprising. Moreover, it’s a logical imperative: In addition to preventing adverse outcomes in newborns, an important benefit of diagnosing GDM is the opportunity to prevent diabetes in the future.

Dr. Coustan is professor of obstetrics and gynecology at the Warren Alpert Medical School of Brown University in Providence, R.I.

COUNTERPOINT: Not yet.

Diagnosing GDM with a single-step approach – rather than a two-step approach – is a positive change. The problem lies not with the one-step 75-g OGTT, but largely with the new diagnostic threshold values for GDM proposed by the IADPSG as part of this new one-step approach.

The HAPO study – the international observational study on which the IADPSG based its recommendations – was a beautiful study. It provided valuable data on the relationship between OGTT values and adverse perinatal outcomes. Unfortunately, but not surprisingly, there was a continuous linear relationship among fasting, 1-hour, and 2-hour glucose values and the frequency of adverse outcomes.

With this linear relationship and no clear-cut off values for normal and abnormal test results, the threshold values are by definition arbitrary. The IADPSG chose to base its diagnostic thresholds on a 1.75-fold increase in the incidence of fetal macrosomia. Using these criteria, approximately 18% of pregnant women worldwide, and 17%-25% of pregnant women in the United States, would be diagnosed as having GDM.

At the current time, there is insufficient evidence that the benefits of such an enormous increase in GDM patients would outweigh the disadvantages.

Two randomized studies have shown that treatment of GDM improves outcomes – lowering the incidence of fetal macrosomia, mortality, birth trauma, and in one study, cesarean delivery – but we do not have strong evidence yet that diagnosing and treating minor glucose abnormalities in all women will significantly improve outcomes.

There also is a real risk of "overmedicalization." A recent article that details driving factors – technological changes detecting even smaller abnormalities, for instance, and conflicted panels writing expanded disease definitions (BMJ 2012;344:e3502) – is acutely applicable to GDM. With lower thresholds, we run the risk of overdiagnosis, which could result in increases in labor inductions and in elective and secondary cesarean deliveries – without proven benefit.

This is starting to happen in Belgium: Data that are as yet unpublished in the medical literature show that the number of labor inductions in women with GDM – women whose diagnoses were made using lower thresholds than previously employed – has been rising. The interventions are driven by concern about presumed large babies, but thus far, signs are lacking of adverse effects in the babies.

With respect to prevention of childhood obesity, we need to consider the fact that while GDM is related to obesity in the offspring, this appears to be mainly in the case of coexisting maternal obesity.

A study from Finland showed that overweight and abdominal obesity in adolescents was associated with maternal obesity, and even more so with the combination of obesity and GDM, but not with GDM itself (Diabetes Care 2010:33;1115-21). Similar U.S. data on childhood metabolic syndrome have been published (Pediatrics 2005:115;e290-6), and a recent meta-analysis has shown that the relationship between diabetes in pregnancy and childhood obesity disappeared after adjustment for maternal BMI (Diabetologia 2011;54:1957-66).

We know from HAPO data too that GDM and obesity are independent risk factors with synergistic effects on short-term outcomes such as preeclampsia, primary cesarean deliveries, macrosomia, increased cord C-peptide levels, and newborn body fat.

As my colleague Dr. Harold W. de Valk and I point out in a recent article, it might be best to use stricter diagnostic thresholds for obese women rather than for all women, given what we know thus far about these synergistic effects and the possibility of a larger effect of obesity on long-term development of offspring (Am. J. Obstet. Gynecol. 2013:208;260-4).

This principle is part and parcel of the so-called Ryan recommendations, which may provide a more sensible alternative to the IADPSG approach. Dr. Ryan proposes that we use a threshold based on a twofold increase in large for gestational age (for an overall incidence of GDM around 10% instead of 18%), that we consider evidence insufficient for the treatment of very mild increases of glucose, except for increases in obese women, and that we continue to collect data and study outcomes (Diabetologia 2011;54:480-6).

A randomized controlled trial stratified for maternal BMI, in which half of the women with OGTT results in between the two proposed diagnostic threshold values are treated, is mandatory.

Dr. de Valk and I have reviewed the published arguments for and against changing the diagnostic criteria for GDM now, and we have other concerns, including the timing and poor reproducibility of the OGTT, the reliance on large for gestational age as an endpoint for setting diagnostic criteria, and the increase in use of oral antidiabetic drugs that could result from a vast increase in GDM.

Overall, we agree with the National Institutes of Health panel that real evidence for change is lacking, and that there is a lot to be done before we significantly expand GDM.

Dr. Visser is professor of obstetrics and gynecology at University Medical Center in Utrecht, the Netherlands.

Based on presentations made at the annual meeting of the Diabetes in Pregnancy Study Group of North America, Washington. Both Dr. Coustan and Dr. Visser reported that they had no conflicts of interest to disclose.