ABSTRACT
Aims/Introduction
We evaluated a simple diagnostic gestational diabetes mellitus (GDM) strategy (Japanese COVID‐19 GDM strategy) published by the Japanese Society of Diabetes and Pregnancy using GDM group data from the Diabetes and Pregnancy Outcomes for Mother and Baby (DREAMBee) study.
Materials and Methods
The study included 803 mothers with GDM diagnosed after 24 gestational weeks using an oral glucose tolerance test and 1,356 with normal glucose tolerance (NGT) from the DREMBee study. They were reclassified by the Japanese COVID‐19 GDM strategies (COVID‐19 GDM and COVID‐19 NGT) using glycated hemoglobin (HbA1c) and random plasma glucose or fasting plasma glucose (FPG) levels. We evaluated the usefulness of the Japanese COVID‐19 GDM strategy and investigated the parameters for diagnosing GDM managed with insulin therapy.
Results
Participants (n = 2,159) were assigned to COVID‐19 GDM (n = 413) and COVID‐19 NGT (n = 1,746) groups. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the Japanese COVID‐19 GDM strategy were 35.4, 90.5, 68.9, and 70.3%, respectively. When the risk factors for insulin therapy were analyzed using a regression model, HbA1c and FPG levels were risk factors for GDM with insulin therapy (P < 0.0001). The cut‐off value of HbA1c was 5.4% (sensitivity, 0.69; specificity, 0.66; PPV, 0.11; NPV, 0.97), and that of FPG was 86 mg/dL (sensitivity, 0.60; specificity, 0.77; PPV, 0.16; NPV, 0.96).
Conclusions
The Japanese COVID‐19 GDM strategy for GDM diagnosis after 24 weeks of gestation might be useful in emergency situations. However, further analysis of GDM outcomes diagnosed using this approach is necessary.
Keywords: COVID‐19, Gestational diabetes mellitus, HbA1c
Participants (2,159) were assigned to COVID‐19 GDM (n = 413) and COVID‐19 NGT (n = 1,746) groups. The sensitivity, specificity, positive predictive value, and negative predictive value of the Japanese COVID‐19 GDM strategy were 35.4, 90.5, 68.9, and 70.3%, respectively.
INTRODUCTION
During the COVID‐19 pandemic, several perinatal complications were influenced. For example, the incidence rates of maternal death, stillbirth, ruptured ectopic pregnancies, and maternal depression increased 1 . Gestational diabetes mellitus (GDM) was influenced by COVID‐19, and the incidence of GDM increased in several countries due to reduced maternal activity and stressful conditions 2 , 3 . For GDM diagnosis, mothers undergo an oral glucose tolerance test (OGTT), and they spend at least 2 h at the hospitals and meet several medical staff members. Therefore, mothers may contract COVID‐19 at the hospitals. Simple diagnostic criteria for GDM were published during the COVID‐19 pandemic in several countries 4 , 5 , 6 . These criteria can improve the identification of low‐risk GDM complications in pregnant women by reducing patient burden and healthcare expenses 7 . However, mean birthweight, the need for cesarean section (CS), large for gestational age (LGA: birthweight ≥90th percentile), neonatal respiratory distress, and admission to the neonatal intensive care unit increased in Australia during the COVID‐19 pandemic due to changes in the GDM criteria 7 . The Japanese Society of Diabetes and Pregnancy (JSDP) published a simple diagnostic GDM strategy on April 10, 2020 (Japanese COVID‐19 GDM strategy) 8 , 9 . This strategy for diagnosing GDM after 24 gestational weeks was established to identify severe GDM without requiring 75 g OGTT. Glycated hemoglobin (HbA1c) and random plasma glucose or fasting plasma glucose (FPG) levels were used to diagnose GDM. However, this strategy did not classify most mothers with GDM as having impaired glucose tolerance group 8 , 9 . Additionally, the Canadian modified GDM strategy during the COVID‐19 pandemic reduced the incidence of GDM but increased the incidence of LGA 10 , 11 . Thus, this strategy was not widely adopted by Japanese institutions 12 . However, to prepare for potential infectious disease outbreaks or natural disasters, more effective and simplified GDM diagnostic criteria must be considered. Therefore, we evaluated the Japanese COVID‐19 GDM strategy published by the JSDP using larger datasets.
We evaluated the Japanese COVID‐19 GDM strategy using GDM group data from the Diabetes and Pregnancy Outcomes for Mother and Baby (DREAMBee) study.
MATERIALS AND METHODS
The DREAMBee Study is a prospective cohort study on impaired glucose tolerance during pregnancy conducted by the JSDP. The study group involved 280 institutions. The details of the DREAMBee study have been described in previous reports 13 , 14 . In the DREAMBee Study GDM group, GDM was diagnosed according to the Japan Society of Obstetrics and Gynecology (JSOG) criteria modified by the International Association of Diabetes and Pregnancy Study Group criteria using a 75 g OGTT 15 . Therefore, the cut‐off values were 92 mg/dL (FPG), 180 mg/dL (1‐h plasma glucose level: 1 h‐PG), and 153 mg/dL (2‐h plasma glucose level: 2 h‐PG). Based on the JSOG criteria, a two‐step procedure was performed to diagnose GDM during the second trimester. The first step is a random plasma glucose test (random PG) with a cut‐off of ≥95 mg/dL or 100 mg/dL or a 50 g glucose challenge test with a cut‐off of ≥140 mg/dL; patients with positive results at the first step receive a 75 g OGTT as the second step. Therefore, some mothers with normal glucose tolerance (NGT) do not receive the 75 g OGTT usually. However, in the DREAMBee Study, all participants, including NGT mothers, received the 75 g OGTT. Furthermore, in Japan, GDM is diagnosed in early gestation using the same 75 g OGTT cut‐off values as in the second trimester. Then, the Japanese COVID‐19 GDM strategy includes criteria for early gestation 9 . However, most institutions participating in the DREAMBee study did not assess first‐trimester HbA1c levels (Figure S1). Therefore, we excluded cases of GDM diagnosed before 20 gestational weeks. In this study, we excluded the following patients according to a previous study: type 1 or 2 diabetes mellitus diagnosed before pregnancy, unknown pregnancy outcomes, NGT diagnosis after 33 gestational weeks, GDM diagnosis after 33 gestational weeks, miscarriage, missing data, NGT diagnosis during early gestational periods using OGTT, and multifetal pregnancy (Figure 1). The participants in the DREAMBee Study GDM group were reclassified using the Japanese COVID‐19 GDM strategy (Figure 2) 12 . The COVID‐19 GDM group comprised patients who were diagnosed with GDM using the Japanese COVID‐19 GDM strategy, while the COVID‐19 NGT group comprised patients who had NGT according to the Japanese COVID‐19 GDM strategy.
Figure 1.
Flow diagram of the study.
Figure 2.
Flow diagram of the simple diagnostic GDM after 24 gestational weeks strategy published on April 10, 2020, by the Japanese Society of Diabetes and Pregnancy.
All the patients provided written informed consent for participation in this study. This study was approved by the ethics committees of the National Center for Child Health and Development and each institution's ethics committee (August 1, 2015; UMIN0000023420).
Study design and participants
Data are presented as numbers (%) and medians (range). Categorical data were analyzed using the chi‐squared or Fisher's exact tests. Continuous data were analyzed using the Mann–Whitney U test. In this study, we aimed to identify pregnant women at high risk by predicting GDM requiring insulin therapy. Therefore, we compared the GDM with insulin therapy group to both the GDM without insulin therapy and NGT groups. Furthermore, we assessed the predictive value of glycemic parameters for GDM requiring insulin therapy using multiple logistic regression and receiver operating characteristic (ROC) analyses. The DeLong test was used to compare the area under the curve (AUC) from ROC. Statistical analysis was performed using JMP Pro software (ver. 17, SAS Institute, Cary, NC, USA), and P‐values <0.05 were considered statistically significant.
RESULTS
A total of 2,159 participants (803 with GDMs and 1,356 with NGTs) were re‐categorized into COVID‐19 GDM (n = 413) and COVID‐19 NGT (n = 1,746) groups using the Japanese COVID‐19 GDM strategy. Among the 803 mothers with GDM, 284 were re‐categorized into the COVID‐19 GDM group and 519 into the COVID‐19 NGT group. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the Japanese COVID‐19 GDM strategy were 35.4, 90.5, 68.9, and 70.3%, respectively. Some mothers in the COVID‐19 GDM group had HbA1c ≥5.7% (n = 212), random PG ≥162 mg/dL (n = 96), and FPG ≥92 mg/dL (n = 188; Table 1). However, among the COVID‐19 NGT group, 1,448 had no data on random PG. Comparisons of maternal characteristics and perinatal outcomes between COVID‐19 GDM and COVID‐19 NGT groups are shown in Table 2. There were no differences in the incidence of family history of diabetes or perinatal outcomes between the two groups. However, maternal age at delivery, pre‐pregnancy body mass index (BMI), FPG, 1 h‐PG, and 2 h‐PG in the COVID‐19 GDM group were significantly higher than those in the COVID‐19 NGT group (P < 0.05).
Table 1.
Results of the Japanese COVID‐19 GDM strategy published by the Japan Diabetes and Pregnancy Society
| COVID‐19 GDM (n = 413) | COVID‐19 NGT (n = 1,746) | |
|---|---|---|
| HbA1c ≥ 5.7% | 212 (51%) | 0 (0%) |
| Random plasma glucose level ≥ 162 mg/dL | 96 (23%) | 0 (0%) |
| Unknown | 258 (62%) | 1,448 (83%) |
| Fasting plasma glucose level ≥ 92 mg/dL | 188 (46%) | 0 (0%) |
Data are n (%). GDM, gestational diabetes mellitus; NGT, normal glucose tolerance.
Table 2.
The comparisons of maternal and perinatal outcomes between COVID‐19 GDM and COVID‐19 NGT
| COVID‐19 GDM (n = 413) | COVID‐19 NGT (n = 1,746) | P‐value | |
|---|---|---|---|
| Maternal age at delivery | 37 (21–51) | 36 (17–53) | <0.01 |
| Pre‐pregnancy BMI (kg/m2) | 22.9 (16.8–42.5) | 20.7 (14.1–43.0) | <0.0001 |
| Pre‐pregnancy BMI ≥25.0 kg/m2 | 129 (31.4%) | 218 (12.5%) | <0.0001 |
| Family history of diabetes | 116 (28.2%) | 429 (24.6%) | 0.15 |
| 75 g OGTT | |||
| Fasting glucose level (mg/dL) | 89 (61–202) | 80 (44–91) | <0.0001 |
| 1‐h glucose level (mg/dL) | 173 (78–282) | 152 (63–237) | <0.0001 |
| 2‐h glucose level (mg/dL) | 141 (69–288) | 127 (62–229) | <0.0001 |
| Gestational weeks at delivery (weeks) | 39 (25–42) | 39 (27–42) | 0.11 |
| Birthweight (g) | 3,104 (268–4,922) | 3,033 (685–4,478) | 0.10 |
| Macrosomia | 6 (1.5%) | 20 (1.2%) | 0.61 |
| Low birthweight | 39 (9.7%) | 170 (9.8%) | 1 |
| Large for gestational age | 68 (17.0%) | 250 (14.7%) | 0.25 |
| Small for gestational age | 27 (6.8%) | 107 (6.3%) | 0.73 |
| Female | 192 (46.9%) | 834 (48.3%) | 0.17 |
| Hypertensive disorder of pregnancy | 20 (7.0%) | 31 (6.0%) | 0.55 |
| Apgar score 1 min | 8 (1–10) | 8 (0–10) | 0.28 |
| Apgar score 5 min | 9 (3–10) | 9 (0–10) | 0.92 |
Data are median (range) or n (%). BMI, body mass index; GDM, gestational diabetes mellitus; OGTT, oral glucose tolerance test.
We compared maternal and perinatal characteristics between mothers with GDM in the COVID‐19 GDM and COVID‐19 NGT groups (Table 3). Pre‐pregnancy BMI, FPG, 1 h‐PG, the number of abnormal values in the diagnostic OGTT, the need for insulin therapy, and birthweight in the COVID‐19 GDM group were significantly higher than those in the COVID‐19 NGT group (P < 0.05). However, 2 h‐PG in the COVID‐19 NGT group was significantly higher than that in the COVID‐19 GDM group (P < 0.05). There were no significant differences in other perinatal outcomes between the two groups.
Table 3.
The comparisons of maternal and perinatal outcomes between COVID‐19 GDM and COVID‐19 NGT in GDM mothers
| COVID‐19 GDM (n = 284) | COVID‐19 NGT (n = 519) | P‐value | |
|---|---|---|---|
| Maternal age at delivery | 37 (21–51) | 36 (24–53) | 0.39 |
| Pre‐pregnancy BMI (kg/m2) | 23.3 (17.3–42.5) | 20.6 (14.9–40.6) | <0.0001 |
| Pre‐pregnancy BMI ≥25.0 kg/m2 | 102 (36.0%) | 65 (12.6%) | <0.0001 |
| Family history of diabetes | 87 (30.6%) | 139 (26.8%) | 0.25 |
| Gestational weeks diagnosed GDM (weeks) | 27 (24–32) | 27 (24–32) | 0.07 |
| 75 g OGTT | |||
| Fasting glucose level (mg/dL) | 93 (68–202) | 81 (44–91) | <0.0001 |
| 1‐h glucose level (mg/dL) | 184 (89–282) | 182 (87–237) | <0.0001 |
| 2‐h glucose level (mg/dL) | 152 (69–288) | 159 (76–229) | <0.0001 |
| Abnormal values of diagnostic OGTT | |||
| Fasting glucose level (≥92 mg/dL) | 186 (65.5%) | 0 (0%) | <0.0001 |
| 1‐h glucose level (≥180 mg/dL) | 165 (58.1%) | 300 (57.8%) | 0.94 |
| 2‐h glucose level (≥153 mg/dL) | 139 (48.9%) | 395 (76.1%) | <0.0001 |
| Number of abnormal values in diagnostic OGTT | |||
| 1 point | 140 (49.3%) | 343 (66.1%) | <0.0001 |
| 2 points | 82 (28.9%) | 176 (33.9%) | |
| 3 points | 62 (21.8%) | 0 (0%) | |
| Insulin therapy | 82 (28.9%) | 66 (12.7%) | <0.0001 |
| Gestational weeks at delivery (weeks) | 39 (27–41) | 39 (29–42) | 0.59 |
| Birthweight (g) | 3,107 (928–4,922) | 3,018 (783–4,192) | 0.01 |
| Macrosomia | 3 (1.1%) | 5 (1.0%) | 1 |
| Low birthweight | 24 (8.5%) | 67 (13.2%) | 0.05 |
| Large for gestational age | 47 (16.9%) | 73 (14.6%) | 0.41 |
| Small for gestational age | 15 (5.4%) | 37 (7.4%) | 0.30 |
| Female | 130 (46.1%) | 255 (50.2%) | 0.20 |
| Apgar score 1 min | 8 (1–10) | 8 (1–10) | 0.93 |
| Apgar score 5 min | 9 (3–10) | 9 (0–10) | 0.87 |
Data are median (range) or n (%). BMI, body mass index; GDM, gestational diabetes mellitus; OGTT, oral glucose tolerance test.
Comparisons of maternal characteristics between GDM with insulin therapy and GDM without insulin therapy and NGT groups are shown in Table 4. Maternal age at delivery, pre‐pregnancy BMI, incidence of obesity, and HbA1c and FPG levels in the GDM with insulin therapy group were significantly higher than those in the GDM without insulin therapy and NGT groups (P < 0.05). However, random PG in the GDM with insulin therapy group was lower than that in the GDM without insulin therapy and NGT groups (P < 0.05). When the risk factors for insulin therapy were analyzed using a regression model, HbA1c and FPG levels were found to be significant risk factors for insulin therapy (P < 0.0001). The cut‐off value of HbA1c was 5.4% (sensitivity, 0.69; specificity, 0.66; PPV, 0.11; NPV, 0.97), and that of FPG was 86 mg/dL (sensitivity, 0.60; specificity, 0.77; PPV, 0.16; NPV, 0.96). The greatest AUC was observed for the combination of HbA1c, FPG, and obesity (pre‐pregnancy BMI ≥25.0 kg/m2; Table 5; Figure S2). However, AUCs for predicting the need for insulin therapy using a combination of HbA1c and FPG, regardless of obesity, were equivalent according to the DeLong test (P = 0.89). Random PG was not a risk factor for the need for insulin therapy (P = 0.05). When we used HbA1c ≥ 5.4% or FPG ≥ 86 mg/dL to diagnose GDM with insulin therapy, the sensitivity, specificity, PPV, and NPV were 0.81, 0.57, 0.12, and 0.98, respectively.
Table 4.
The comparison of maternal characteristics between gestational diabetes mellitus with insulin therapy and gestational diabetes mellitus without insulin therapy and normal glucose tolerance
| GDM with insulin therapy (n = 145) | GDM without insulin therapy and NGT (n = 2,014) | P‐value | |
|---|---|---|---|
| Maternal age at delivery (age) | 36.3 ± 4.5 | 35.4 ± 5.0 | 0.04 |
| Pre‐pregnancy BMI (kg/m2) | 23.4 ± 4.7 | 21.8 ± 3.8 | <0.0001 |
| Pre‐pregnancy BMI≥25 kg/m2 | 48 (33%) | 299 (15%) | <0.0001 |
| HbA1c (%) | 5.5 ± 0.3 | 5.2 ± 0.3 | <0.0001 |
| Unknown | 28 (19%) | 119 (6%) | |
| Random plasma glucose level (mg/dL) | 130.5 ± 38.6 | 140.5 ± 30.1 | 0.049 |
| Unknown | 105 (72%) | 1,604 (80%) | |
| Fasting plasma glucose level (mg/dL) | 87.9 ± 10.4 | 81.5 ± 7.4 | <0.0001 |
Data are average ± standard deviation or n (%). BMI, body mass index.
Table 5.
Predictive values of clinical characteristics for the risk of insulin therapy in gestational diabetes
| AUC | Cut‐off | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | |
|---|---|---|---|---|---|---|
| HbA1c | 0.74 | 5.4 | 69 | 66 | 11 | 97 |
| FPG | 0.74 | 86 | 60 | 77 | 16 | 96 |
| HbA1c + FPG | 0.78 | – | 62 | 80 | 16 | 97 |
| HbA1c + FPG + obesity | 0.78 | – | 66 | 77 | 14 | 97 |
AUC, area under the curve; CI, confidence interval; FPG, fasting plasma glucose level; NPV, negative predictive value; PPV, positive predictive value.
DISCUSSION
We confirmed the Japanese COVID‐19 GDM strategy of diagnosing after 24 weeks of gestation using the DREAMBee study data. Since the Japanese COVID‐19 GDM strategy had higher specificity, it was a good diagnostic criterion for diagnosing NGT as COVID‐19 NGT. Furthermore, because the incidences of obesity and insulin therapy during pregnancy in COVID‐19 GDM were significantly higher than those in COVID‐19 NGT among mothers with GDM, the Japanese COVID‐19 GDM strategy can be used to diagnose high‐risk mothers. HbA1c and FPG levels might be good predictors for diagnosing GDM requiring insulin therapy.
As in previous reports, the diagnostic rate of GDM using the Japanese COVID‐19 GDM strategy was not so high 8 , 9 , 16 . During emergency situations such as infectious disease pandemics or natural disasters, it is important to avoid treating pregnant women who do not require treatment to save medical resources. Considering the results of this study, the Japanese COVID‐19 GDM strategy may be useful in emergency situations because of its high specificity. Although the DREAMBee was a prospective study, the present study is a retrospective study that evaluated the Japanese COVID‐19 GDM strategy. Therefore, perinatal outcomes could not be evaluated in pregnant women diagnosed using the Japanese COVID‐19 GDM strategy. While a simple modified diagnostic strategy during the COVID‐19 pandemic has been proposed to identify patients with adverse complications, the incidence of neonatal hypoglycemia or need for CS between the false‐negative and true‐positive groups was not different when classified using the Canadian and British diagnostic criteria 10 . Further research is required to evaluate perinatal outcomes after diagnosis using the Japanese COVID‐19 GDM strategy.
To save medical resources, the criteria for investigating high‐risk mothers with GDM should be considered. Among mothers with GDM, incidences of obesity, insulin therapy, and birthweight in the COVID‐19 GDM group were higher than those in the COVID‐19 NGT group. Therefore, the Japanese COVID‐19 GDM strategy may be a good criterion for high‐risk mothers with GDM during emergencies. However, mothers with GDM receiving insulin therapy had a higher risk of adverse outcomes. In Japanese women, the risk factors for insulin therapy were pre‐pregnancy obesity, family history of diabetes, and abnormal FPG, 1 h‐PG, and 2 h‐PG in previous reports 17 , 18 . Furthermore, insulin therapy during pregnancy is a risk factor for neonatal hypoglycemia 19 . In this study, the HbA1c and FPG levels were good predictors of GDM in patients treated with insulin therapy. According to a comparison between insulin and diet therapy in patients with GDM, the insulin therapy group had several adverse perinatal outcomes 19 . A previous report stated that the sensitivity of the modified GDM criteria during COVID‐19 by the French‐speaking Society of Diabetes using HbA1c and FPG levels was 57%, and the criteria could not identify patients with adverse perinatal complications 17 . When we used HbA1c ≥ 5.4% or FPG ≥86 mg/dL to diagnose GDM with insulin therapy in this study, the sensitivity was 81%. However, adding obesity to the diagnostic criteria may yield greater diagnostic accuracy. Our recommendation might be a good cut‐off to diagnose GDM during any emergency situations.
This study has some limitations. In Japan, there are two opportunities for diagnosing GDM: less than 20 gestational weeks (early GDM) and after 24 gestational weeks (late GDM) 20 . Since the Japanese COVID‐19 GDM strategy indicated early GDM, we aimed to evaluate its usefulness using the DREAMBee study data. However, HbA1c levels in the first trimester were not assessed in most institutions that participated in the DREAMBee study (Figure S1). Therefore, we could not evaluate the Japanese COVID‐19 GDM strategy for GDM diagnosis before 20 weeks of gestation. Second, the sample size was not large enough to suggest new criteria for GDM in other emergency situations. Third, the management of GDM was not the same in each institution, and there were some missing data, such as HbA1c. In particular, many patients did not undergo random PG testing (Table 1). If all patients were checked for random PG, some might have been categorized into another group. Fourth, HbA1c and FPG levels are good parameters for diagnosing late GDM treated with insulin therapy. However, the incidence of insulin therapy and obesity in early GDM is higher than that in late GDM 14 , 21 . Since we were unable to evaluate early GDM in this study, there might be some biases.
The Japanese COVID‐19 GDM strategy for GDM diagnosis after 24 weeks of gestation may be useful in emergency situations, and HbA1c and FPG might be good predictors to diagnose GDM with insulin therapy. However, adjusting the cut‐off values may improve diagnostic accuracy. To evaluate the effectiveness of the Japanese COVID‐19 GDM strategy, further analysis of GDM outcomes diagnosed using this approach is necessary.
DISCLOSURE
The authors declare no conflicts of interest. Hiroto Sone is an Editorial Board member of the Journal of Diabetes Investigation and a co‐author of this article. To minimize bias, he was excluded from all editorial decision‐making related to the acceptance of this article for publication.
Approval of the research protocol: The protocol for this research project was approved by the National Center for Child Health and Development and each institution's ethics committee (approval No. 868, August 1, 2015). The study conforms to the provisions of the Declaration of Helsinki.
Informed consent: Written informed consent was obtained from all patients.
Approval date of registry and the registration no. of the study/trial: UMIN0000023420, August 2016.
Animal Studies: N/A.
Supporting information
Figure S1. Flow diagram of the simple diagnostic GDM before 24 gestational weeks strategy published on April 10, 2020 by the Japanese Society of Diabetes and Pregnancy.
Figure S2. Receiver operating characteristic (ROC) curve analyses for insulin therapy. (a) A cut‐off value of HbA1c at 5.4%, with an area under the ROC curve of 0.74. (b) A cut‐off value of a fasting plasma glucose level at 86 mg/dL, with area under the ROC curve of 0.74.
Appendix S1. DREAMBee Study Gestational Diabetes Mellitus Group.
ACKNOWLEDGMENTS
We thank the medical staff for caring for expectant mothers at each institution. We also thank Editage (www.editage.jp) for English language editing.
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Associated Data
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Supplementary Materials
Figure S1. Flow diagram of the simple diagnostic GDM before 24 gestational weeks strategy published on April 10, 2020 by the Japanese Society of Diabetes and Pregnancy.
Figure S2. Receiver operating characteristic (ROC) curve analyses for insulin therapy. (a) A cut‐off value of HbA1c at 5.4%, with an area under the ROC curve of 0.74. (b) A cut‐off value of a fasting plasma glucose level at 86 mg/dL, with area under the ROC curve of 0.74.
Appendix S1. DREAMBee Study Gestational Diabetes Mellitus Group.