key: cord-0871233-77v1c6kz authors: Sugiyama, Kazutoshi; Saisho, Yoshifumi; Kasuga, Yoshifumi; Ochiai, Daigo; Itoh, Hiroshi title: Clinical utility of 1‐month postpartum random plasma glucose and glycated hemoglobin combined with pre‐pregnancy body mass index for detecting postpartum glucose intolerance in Japanese women with gestational diabetes date: 2021-07-28 journal: J Diabetes Investig DOI: 10.1111/jdi.13612 sha: 48c089c521b7518a08faf50ab049772dd08c4e10 doc_id: 871233 cord_uid: 77v1c6kz During the coronavirus disease 2019 pandemic, the Japanese Society of Diabetes and Pregnancy proposed the use of random plasma glucose and glycated hemoglobin measured 1 month after delivery combined with pre‐pregnancy body mass index to detect postpartum glucose intolerance instead of carrying out the oral glucose tolerance test in women with gestational diabetes. We retrospectively evaluated the clinical utility of this strategy to detect postpartum glucose intolerance evaluated by the oral glucose tolerance test after delivery. A total of 275 Japanese women with gestational diabetes were included in the present study. The specificity of 1‐month postpartum random plasma glucose and glycated hemoglobin combined with pre‐pregnancy body mass index to predict postpartum glucose intolerance was 98.0%, with a negative predictive value of 72.6%. However, sensitivity was 6.4%, with a positive predictive value of 55.6%. In conclusion, this Japanese Society of Diabetes and Pregnancy strategy showed high specificity, but low sensitivity, for detecting glucose intolerance postpartum. Women with gestational diabetes mellitus (GDM) are at high risk of developing glucose intolerance after delivery. Approximately 20% of women with GDM have impaired glucose tolerance (IGT) during the early postpartum period 1 . In the long term, women with GDM have a nearly 10-fold higher risk of developing type 2 diabetes mellitus than women with normoglycemic pregnancies 2 . Therefore, medical societies recommend that women with GDM undergo a 75-g oral glucose tolerance test (OGTT) between 6 and 12 weeks postpartum, and periodically thereafter 3, 4 . Because of the coronavirus disease 2019 (COVID-19) pandemic, the Japanese Society of Diabetes and Pregnancy (JSDP) proposed a modified postpartum screening method, aiming at reducing the risk of COVID-19 infection by shortening the time spent in the hospital. Specifically, at the 1-month postpartum obstetric checkup, measurement of random plasma glucose (PG) and glycated hemoglobin (HbA1c) was recommended. Patients with random PG ≥200 mg/dL or HbA1c ≥6.5% were treated as having type 2 diabetes mellitus. Patients with HbA1c of 5.7-6.4% and pre-pregnancy body mass index (BMI) ≥25 kg/m 2 were rechecked with either an OGTT or fasting PG and HbA1c at 6 months. The remainder of the patients were re-checked with either an OGTT or fasting PG and HbA1c at 12 months. However, this modified strategy (hereinafter, referred to as the JSDP criteria) has not been clinically validated. Thus, this current study aimed to evaluate the clinical utility of the JSDP criteria to detect postpartum glucose intolerance based on OGTT carried out within 6 months after delivery. Among Japanese women who gave birth at Keio University Hospital (Tokyo, Japan) between July 2012 and September 2020, those with GDM who had random PG and HbA1c measured within 45 days after delivery, and subsequently underwent an OGTT within 180 days after delivery were included in the present retrospective study. Women underwent two-step screening for GDM with random PG and 1-h 50-g oral glucose challenge test in early and mid-pregnancy, respectively, based on the recommendations of the Japan Society of Obstetrics and Gynecology 5 . Women with a positive screen underwent a diagnostic 75-g OGTT using the International Association of Diabetes and Pregnancy Study Group criteria; that is, fasting PG ≥92 mg/dL, 1-h PG ≥180 mg/dL or 2-h PG ≥153 mg/dL 6 . Those with overt diabetes in pregnancy (fasting PG ≥126 mg/dL or HbA1c ≥6.5%) and pre-pregnancy diabetes were excluded from the present study. In addition, those treated with glucocorticoids or ritodrine hydrochloride at the time of GDM diagnosis, and those with multiple pregnancy were also excluded. Glucose tolerance status in the postpartum OGTT was defined according to the World Health Organization criteria 7 . Normal glucose tolerance was defined as fasting PG <110 mg/dL and 2-h PG <140 mg/dL, impaired fasting glucose was defined as fasting PG 110-125 mg/dL and 2-h PG <140 mg/dL, IGT was defined as fasting PG <126 mg/dL and 2-h PG 140-199 mg/dL, and type 2 diabetes mellitus was defined as fasting PG ≥126 mg/dL or 2-h PG ≥200 mg/dL. Glucose intolerance was defined as impaired fasting glucose, IGT or type 2 diabetes mellitus.The protocol for this research project has been approved by a suitably constituted ethics committee of the institution and it conforms to the provisions of the Declaration of Helsinki. Ethics Committee of Keio University School of Medicine, Approval No. 20110321 (approval date 9 March 2012). A waiver of informed consent was approved because of the retrospective nature of the study. Sensitivity, specificity and predictive value of the JSDP criteria to detect postpartum glucose intolerance based on OGTT after delivery were evaluated. All statistical analyses were carried out using the Statistical Package for the Social Sciences software for Windows version 27.0 (IBM Corp., Armonk, NY, USA). A total of 721 Japanese women were diagnosed as having GDM during the study period. Among them, 362 (50.2%) underwent OGTT within 180 days after delivery, of whom 312 had random PG and HbA1c measured within 45 days after delivery. Of these women, 37 were excluded as follows: 23 were treated with glucocorticoids or ritodrine hydrochloride at the time of GDM diagnosis, and 14 had multiple pregnancy. As a result, 275 women were included in the final analysis (Figure 1) . Table 1 presents the characteristics of the study patients. At the 1-month postpartum checkup, no patient had random PG ≥200 mg/dL or HbA1c ≥6.5%. Nine (3%) patients had HbA1c of 5.7-6.4% and pre-pregnancy BMI ≥25 kg/m 2 , of whom four (44%) patients were diagnosed as having normal glucose tolerance, and five (56%) as having IGT based on the postpartum OGTT (median 98 days after delivery). A total of 266 (97%) patients did not meet either of the aforementioned criteria, of whom 193 (73%) were diagnosed as having normal glucose tolerance and 73 (27%) as having glucose intolerance based on the postpartum OGTT ( Table 2) . Table 3 presents the sensitivity, specificity and predictive value of the JSDP criteria for detecting glucose intolerance based on the postpartum OGTT. Specificity was 98.0%, with a negative predictive value of 72.6%. However, sensitivity was 6.4%, with a positive predictive value of 55.6%. In the current study, the JSDP criteria showed high specificity, but low sensitivity, for detecting glucose intolerance. The JSDP states that women negative for these criteria should be rechecked in 12 months during the COVID-19 pandemic. Based on the present results, this strategy is likely to be beneficial in reducing the number of non-urgent postpartum OGTTs and shortening the time spent in hospital. However, the importance of carrying out postpartum OGTT in women with GDM should be noted, because lifestyle intervention for women with glucose intolerance detected by OGTT has been shown to be effective in reducing the progression to type 2 diabetes mellitus 8, 9 . A meta-analysis of 95,750 women with GDM found that high BMI, family history of type 2 diabetes mellitus, nonwhite ethnicity, advanced maternal age, early diagnosis of GDM, high PG levels in OGTT, high HbA1c, use of insulin, multiparity, hypertension and preterm delivery were significant risk factors for progression to type 2 diabetes mellitus 10 . We 11 and others 12,13 have reported 2-h PG in antepartum OGTT to be a risk factor for postpartum glucose abnormalities in Japanese women with GDM. Lower insulin secretion (i.e., insulinogenic index) and b-cell function (i.e., insulin secretion-sensitivity index 2) have also been shown to be associated with an increased risk of postpartum glucose abnormalities 11, 14, 15 . Therefore, incorporating the aforementioned risk factors in determining when each individual woman should receive postpartum OGTT might be a reasonable strategy. In addition, a recent study showed that 2-day postpartum OGTT during hospitalization for delivery had similar diagnostic value to 4-to 12-week postpartum OGTT in predicting glucose abnormalities at 1 year after delivery 16 . As testing adherence of nearly 100% can be achieved during hospitalization, and postpartum hospital visits can be minimized, this approach might be especially beneficial during the COVID-19 pandemic. There were several limitations to the current retrospective study. First, the study was carried out at a single university hospital in Tokyo, and the sample size was small. In 17 . Second, the rate of postpartum OGTT carried out within 6 months after delivery was 50.2%, which might have caused selection bias. Third, information on breast-feeding, which might have a protective effect on the development of glucose abnormalities [18] [19] [20] , was lacking. In conclusion, the 1-month postpartum random PG and HbA1c combined with pre-pregnancy BMI showed high specificity, but low sensitivity, for detecting glucose intolerance. As women with GDM often discontinue checkups after delivery 21 , it remains important to state that efforts should be focused on preventing missed opportunities for postpartum OGTT during the COVID-19 pandemic. Incorporating risk factors associated with the development of type 2 diabetes mellitus and utilizing postpartum OGTT during hospitalization for delivery might be valuable options, so that women with GDM do not miss the opportunity for early lifestyle intervention, while minimizing the risk of COVID-19 infection. Glucose intolerance was defined as impaired fasting glucose, impaired glucose tolerance or type 2 diabetes mellitus. Gestational diabetes after delivery. 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Annual Report on the Declining Birthrate 2020 Lactation intensity and postpartum maternal glucose tolerance and insulin resistance in women with recent GDM: the SWIFT cohort Lactation and progression to type 2 diabetes mellitus after gestational diabetes mellitus: a prospective cohort study The effect of highintensity breastfeeding on postpartum glucose tolerance in women with recent gestational diabetes Postpartum glucose intolerance: an updated overview The authors thank Wendy Gray, self-employed, for English editing. The authors declare no conflict of interest.