Diabetes in Pregnancy in Korea: Prevalence, Clinical Characteristics, and Postpartum Comorbidities

Article information

Diabetes Metab J. 2026;50(2):280-290

Publication date (electronic) : 2026 March 1

doi : https://doi.org/10.4093/dmj.2025.1161

Joon Ho Moon^1,*, Han Na Jung^2,*, Bongseong Kim³, Seung-Hyun Ko⁴, Soo Heon Kwak⁵, Kyung-Do Han^,3, Sung Hee Choi^,1, on Behalf of the Committee of Public Relation of the Korean Diabetes Association

¹Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea

²Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Korea

³Department of Statistics and Actuarial Science, College of Natural Sciences, Soongsil University, Seoul, Korea

⁴Division of Endocrinology and Metabolism, Department of Internal Medicine, St. Vincent’s Hospital, College of Medicine, The Catholic University of Korea, Suwon, Korea

⁵Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea

Corresponding authors: Sung Hee Choi https://orcid.org/0000-0003-0740-8116 Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam 13620, Korea E-mail: shchoimd@gmail.com

Kyung-Do Han https://orcid.org/0000-0002-9622-0643 Department of Statistics and Actuarial Science, College of Natural Sciences, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Korea E-mail: hkd917@naver.com

*Joon Ho Moon and Han Na Jung contributed equally to this study as first authors.

Received 2025 November 16; Accepted 2026 February 10.

Abstract

GRAPHICAL ABSTRACT

Highlights

INTRODUCTION

Diabetes in pregnancy (DIP), encompassing both gestational diabetes mellitus (GDM) and pregestational diabetes mellitus (PGDM), represents an increasingly critical global health challenge. GDM now complicates an estimated more than 10% of pregnancies worldwide, though prevalence varies widely across regions and diagnostic approach [1-3]. Similarly, PGDM is rising globally in parallel with the growing prevalence of obesity and diabetes among women of reproductive age [4-6]. Both PGDM and GDM pose significant risks to maternal and perinatal outcomes, including preterm delivery, preeclampsia, cesarean birth, macrosomia, and neonatal morbidity, and are also linked to long-term maternal sequelae including cardiometabolic disease [7-9]. Furthermore, intrauterine exposure to maternal hyperglycemia is associated with adverse metabolic imprinting in offspring, predisposing them to obesity and type 2 diabetes mellitus (T2DM) in later life [7,8-12].

The rising prevalence of DIP is largely attributable to advancing maternal age, obesity, sedentary lifestyle, and unhealthy dietary factors [13-15]. Asian populations are particularly susceptible to DIP even with comparably lower body mass index (BMI), with recent increases in obesity accompanied by carbohydrate-rich diet and reduced physical activity [16]. Substantial evidence indicates that Asian women have a higher prevalence of GDM than those of European descent, underscoring their unique vulnerability to metabolic risk [14,17-19]. Nevertheless, contemporary data on the epidemiology and clinical characteristics of DIP in Asian populations, including Korea, remain understudied, with risk factor profiles more extensively documented in Western cohorts.

International guidelines recommend universal screening for GDM during pregnancy and subsequent postpartum screening for T2DM [20-22]. Women with a history of GDM have up to a tenfold higher risk of developing diabetes after delivery compared with those without GDM [3]. Multiethnic cohort studies have further demonstrated that Asian women are at particularly high risk of postpartum diabetes compared to women with European ancestry [23,24]. Despite these elevated risks, postpartum surveillance rates remain suboptimal, largely due to the demands of childcare and competing priorities during the postpartum period [25]. Moreover, women with prior GDM are at a two- to threefold higher risk of developing cardiovascular disease (CVD) later in life [3]. In Korea, however, the current rate and determinants of postpartum diabetes surveillance remain poorly characterized. These gaps highlight the need to assess nationwide practices of DIP management and their implications for long-term health outcomes. Therefore, this study aimed to examine clinical characteristics, maternal risk factors, and management of DIP, and subsequent cardiovascular risk in Korean women.

METHODS

RESULTS

Demographic and clinical characteristics

Baseline characteristics according to diabetes status in pregnancy are summarized in Table 1. Across the groups of no DIP, GDM, and PGDM, women were progressively older at delivery, had higher prepregnancy BMI, WC, blood pressure, and FPG, and showed a progressively less favorable lipid profile. The prevalence of current smoking and regular exercise before pregnancy was higher in women with GDM and PGDM compared with those without DIP. The prevalence of hypertension, dyslipidemia, and depression was higher in women with GDM and PGDM.

Table 1.

Characteristics according to diabetes status in pregnancy

Prevalence of diabetes in pregnancy

The prevalence of DIP was compared between 2014–2018 and 2019–2023 (Fig. 1, Supplementary Table 1) [27]. The average number of total deliveries decreased from 366,765 in 2014–2018 to 243,277 in 2019–2023. The absolute number of GDM cases declined from 32,400 to 29,003, whereas the proportion among total deliveries increased from 8.8% to 11.9%. By contrast, the prevalence of PGDM increased in both absolute number and proportion, from 3,959 (1.1%) to 4,134 (1.7%), despite the reduction in total deliveries. The majority of PGDM were T2DM, with T2DM accounting for 89.7%–94.9% of PGDM (0.97%–1.61% of all deliveries), whereas T1DM accounted for 5.1%–10.3% of PGDM (0.09%–0.11% of all deliveries).

Fig. 1.

Comparison of the prevalence of diabetes in pregnancy between 2014–2018 and 2019–2023. The mean annual numbers of women with gestational diabetes mellitus (GDM) and pregestational diabetes mellitus (PGDM) are presented as bars (left y-axis), and their corresponding prevalence rates (%) are shown as dots with connecting lines (right y-axis).

The prevalence of DIP according to maternal age at delivery for births between 2019 and 2023 showed that both GDM and PGDM were more common at older ages (Fig. 2). Among women <20 years, the prevalence was 5.5% for GDM and 0.6% for PGDM, whereas it was 18.6% and 3.9% among those ≥40 years, respectively. In women aged 30–34 years, who accounted for 43.4% of all deliveries, the prevalence was 10.7% for GDM and 1.3% for PGDM. The prevalence of DIP was higher in women with greater prepregnancy BMI and WC. Among women who were underweight (BMI <18.5 kg/m²) before pregnancy, 8.4% were diagnosed with GDM and 0.5% with PGDM, whereas in those with obesity (BMI ≥25 kg/m²), the prevalence was 19.2% and 5.2%, respectively. The corresponding prevalence in women with class 2 or 3 obesity (BMI ≥30 kg/m²) was 23.5% and 10.6%, respectively. Similarly, the prevalence of GDM and PGDM was 8.2% and 0.4% among women with a WC <65 cm, in contrast to 20.5% and 7.0% among those with abdominal obesity (WC ≥85 cm). Women with higher FPG levels before pregnancy were more frequently diagnosed with GDM, with a prevalence of 20.5% among those with impaired fasting glucose (FPG ≥100 mg/dL).

Fig. 2.

Prevalence of diabetes in pregnancy according to age and metabolic factors. (A) Age at delivery (years). (B) Prepregnancy body mass index (kg/m²). (C) Prepregnancy waist circumference (cm). (D) Prepregnancy fasting plasma glucose (mg/dL). All among women who delivered between 2019 and 2023. GDM, gestational diabetes mellitus; PGDM, pregestational diabetes mellitus.

The prevalence of PGDM was lower with higher income levels, whereas this pattern was not observed for GDM (Supplementary Fig. 2). However, the prevalence of GDM was highest at 12.4% among women in the lowest income quartile or receiving medical aid. Among all women, 3.1% had preexisting hypertension, of whom 16.5% were diagnosed with GDM and 9.7% with PGDM. In addition, 2.1% had preexisting dyslipidemia, with corresponding prevalences of 16.8% and 21.9%, respectively.

Diabetes management during pregnancy and postpartum

Patterns of diabetes management during pregnancy in women with DIP were compared between 2014–2018 and 2019–2023 (Fig. 3, Supplementary Table 2). The majority of women with GDM were treated with lifestyle modification alone, accounting for 91.8% in 2014–2018 and 90.7% in 2019–2023. The proportion receiving insulin therapy increased modestly from 8.1% to 9.2%. Only a small fraction received OAD, 0.3% in 2014–2018 and 0.1% in 2019–2023, with metformin comprising 94.0% and 99.4% of OAD prescriptions, respectively. In women with PGDM, the proportion managed with lifestyle modification alone decreased from 28.5% to 23.6%, whereas those treated with insulin increased from 67.3% to 70.9%. Use of OAD accounted for 4.2% and 5.5%, with metformin representing 96.9% and 97.7% of OAD prescriptions.

Fig. 3.

Comparison of glycemic management strategies during pregnancy for diabetes in pregnancy between 2014–2018 and 2019–2023. Stacked bar graphs show the distribution of management modalities: lifestyle modification, insulin only, oral antidiabetic drug (OAD) only, and insulin combined with OAD. GDM, gestational diabetes mellitus; PGDM, pregestational diabetes mellitus.

Rates of postpartum glycemic follow-up within 1 year after delivery increased progressively in women with DIP between 2018 and 2022 (Supplementary Fig. 3). Among deliveries in 2018, 32.0% of women with GDM and 61.1% with PGDM underwent follow-up testing, whereas the corresponding rates in 2022 were 42.9% and 68.1%, respectively. In women with GDM, follow-up testing was more frequently performed with plasma glucose than with HbA1c, whereas in women with PGDM the proportions were comparable.

Long-term risk of cardiovascular disease

CVD occurred in 32,747 (1.1%), 1,488 (1.4%), and 764 (4.1%) women with no DIP, GDM, and PGDM, respectively, during a median follow-up of 16.2 (interquartile range [IQR], 13.2 to 18.5), 13.4 (IQR, 11.5 to 16.3), and 14.7 (IQR, 12.1 to 17.2) years (Table 2). The incidence rates were 2.8 per 1,000 person-years for those with PGDM, in contrast to 0.7 for those without DIP. The risk of CVD was gradually higher in women with GDM and PGDM compared with those without DIP across all adjustment models (adjusted hazard ratio [aHR], 1.47; 95% CI, 1.40 to 1.55 for GDM; aHR, 3.04; 95% CI, 2.82 to 3.28 for PGDM in the fully adjusted model). Analyses of MI and ischemic stroke separately yielded similar results.

Table 2.

Risk of cardiovascular disease according to diabetes status in pregnancy (n=3,068,834 women who delivered between 2003 and 2013)

DISCUSSION

In this study, we investigated the clinical characteristics of DIP among Korean women using nationwide claims data linked to the national health screening program. In 2023, the prevalence of GDM and PGDM was 12.4% and 2.1%, respectively. The incidence of both GDM and PGDM increased with advancing maternal age, higher prepregnancy BMI, and greater WC. Women with pregestational hypertension and dyslipidemia had higher prevalence for both GDM and PGDM. Regarding glycemic management during pregnancy, approximately 90% of women with GDM were managed with lifestyle modification alone, while 10% required pharmacologic therapy, almost exclusively with insulin monotherapy. Among women with PGDM, about 70% were treated with insulin alone, whereas 5% used OAD. The rate of postpartum diabetes screening has shown an increasing trend in recent years; however, more than half of women with GDM did not undergo any follow-up testing after delivery. Among women with PGDM, approximately one-third did not receive postpartum surveillance either. Regarding long-term outcomes, a study published concurrently with the present work reported that women with GDM had a 6.07-fold higher risk of developing postpartum T2DM compared with those without GDM [27]. Likewise, the risks of cardiovascular and cerebrovascular diseases were elevated in DIP, being 1.47-fold higher in women with GDM and 3.04-fold higher in those with PGDM than in those without DIP, highlighting the need for improved postpartum surveillance and preventive care in this high-risk population.

Previous studies on the epidemiology of GDM in Korea have reported varying results [28-30]. In a prospective cohort study conducted at Korean hospitals between 2014 and 2016, the incidence of GDM ranged from 2.1% to 4.1% [28]. In contrast, a study using the Health Insurance Review and Assessment database, in which GDM was defined based on ICD-10 codes, demonstrated an increasing trend in prevalence from 5.7% in 2009 to 9.5% in 2011, consistent with the findings of the present study [29]. Meanwhile, the graded increase in the prevalence of DIP with advancing maternal age and adiposity observed in our study accords with evidence mainly from Western populations. A meta-analysis of more than 120 million pregnancies has shown that the risk of GDM increased linearly with maternal age, being approximately 4.9-fold higher in women aged ≥40 years compared with those aged <20 years [13]. The positive association of BMI with GDM prevalence is consistently robust across racial and ethnic groups [18]. Maternal abdominal obesity early in pregnancy also confers a 2.8- fold higher risk of GDM compared with normal WC in pooled cohort analyses [31]. Similarly, in UK population data, women with pregestational T2DM were on average 3 years older and had 6.5 kg/m² higher BMI than those without PGDM [32]. Of particular concern, obesity and abdominal obesity among Korean women of reproductive age have risen sharply over the past decade, nearly doubling in women in their twenties and increasing by approximately 1.5- to 1.7-fold in those in their thirties [33], implying that the burden of DIP in Korea is likely to continue increasing. Furthermore, in Korea, the mean maternal age at childbirth reached 33.5 years in 2022, which is 2.5 years higher than the Organisation for Economic Co-operation and Development (OECD) average, while the total fertility rate dropped to 0.72 in 2023, the lowest among OECD countries [34]. This phenomenon underscores the societal and healthsystem importance of preventing high-risk pregnancies including DIP. Collectively, these metabolic and demographic transitions highlight the growing urgency for preconception risk reduction and early pregnancy screening in high-risk Korean women.

Several studies have reported that Asian women have a relatively higher risk of GDM despite lower BMI compared with other ethnic groups, suggesting ethnic-specific susceptibility beyond adiposity alone [35,36]. In particular, impaired β-cell compensation relative to insulin resistance has been proposed as an underlying mechanism contributing to this increased risk in Asian populations [37]. Hedderson et al. [18] observed that Asian women had a higher prevalence of GDM than Caucasian women within similar BMI categories, consistent with a possible defect in β-cell compensation for insulin resistance in Asians. As recovery of β-cell function has been identified as a key determinant of prediabetes remission in GDM women [38], this mechanism may be especially important in Korean individuals, who generally exhibit reduced baseline β-cell function compared with Western populations, underscoring the need for careful surveillance and timely intervention.

Despite widely endorsed guidelines providing standardized recommendations, global real-world data indicate persistent heterogeneity in postpartum diabetes surveillance after GDM. A systematic review encompassing multiple ethnic groups reported that 34%–73% of women with GDM underwent postpartum glycemic testing, with a median completion rate of approximately 48% [39]. Likewise, in large integrated U.S. healthcare systems, only about half of women completed glycemic testing within 6 months postpartum [40]. Although our study reflects data collected nearly a decade more recent than earlier reports, the overall rate of postpartum surveillance in women with GDM remains comparably low, and follow-up remains strikingly inadequate even among those with PGDM. Notably, plasma glucose testing may occur for reasons other than diabetes surveillance, as Korea’s Universal National Health Screening Program and routine inpatient laboratory panels include glucose measurements. Considering this context, the finding that HbA1c follow-up in 2022 remained limited at 26.8% in GDM and 58.8% in PGDM underscores the need for nationally coordinated, system-level strategies to enhance continuity of postpartum diabetes care. Guideline publication alone has not translated into better practice, as illustrated by the experience in England, where the introduction of the national DIP guideline in 2008 had no measurable impact on long-term followup, with annual testing rates remaining around 20% [41]. Higher educational attainment has been identified as a predictor of better adherence to postpartum screening [39], suggesting that individualized education and active patient engagement are essential. For example, targeted interventions integrated with primary care, such as electronically generated reminders, automated phone or e-mail messages, and scheduled appointments before delivery discharge, could be embedded into national digital health systems to enhance follow-up.

In our cohort, both incidence and risk of CVD were substantially elevated after pregnancy complicated by diabetes, showing a stepwise increase from no DIP through GDM to PGDM. Among women with GDM, the absolute incidence rates were comparable to those reported in large Western population studies such as the nationwide Danish registry study and the U.S. Nurses’ Health Study II, which reported 0.6–1.7 and 0.5–1.0 per 1,000 person-years for MI and stroke, respectively [42,43]. Studies explicitly quantifying CVD risk in PGDM are limited, but our data reveal markedly higher incidence rates in PGDM, indicating an accelerated atherosclerotic burden associated with preexisting diabetes beyond that seen with GDM. The elevated CVD risk observed in our study aligns with a recent pooled analysis of 15 studies predominantly conducted in Western populations, showing a 45% higher risk of overall cardiovascular and cerebrovascular diseases in women with prior GDM [44]. Despite lower prevalence of obesity and insulin resistance among Asian women of reproductive age compared with their Western counterparts [45], the similarity in magnitude of incidence and risk elevation in our Korean cohort suggests an enhanced cardiovascular vulnerability once pregnancy-related hyperglycemia develops. Importantly, the adverse cardiometabolic trajectory remains evident from within 1 year postpartum through more than 10 years [8,46]. In addition, a sensitivity analysis limited to participants with available lifestyle and socioeconomic data demonstrated that the graded increase in CVD risk across no DIP, GDM, and PGDM remained consistent after additional adjustment for income, smoking, alcohol intake, and physical activity (data not shown). Taken together, these findings reinforce that postpartum monitoring should extend beyond glycemic testing to sustained cardiometabolic surveillance, early intervention, and integration into comprehensive CVD prevention frameworks in women with DIP. Future studies are warranted to identify factors that further stratify cardiovascular risk within DIP subgroups, including prepregnancy adiposity, metabolic profiles, and socioeconomic or lifestyle characteristics, to inform targeted postpartum prevention strategies.

The principal strengths of this study include its nationwide coverage and comprehensive longitudinal design, enabling precise estimation of the prevalence, clinical characteristics, and management of DIP across all deliveries in Korea. The large sample size allowed for robust comparisons of cardiovascular outcomes across diabetes status during pregnancy, which have a low incidence in young women. Furthermore, the study incorporated temporal analyses spanning a decade, offering contemporary insights into evolving demographic and metabolic patterns among women of reproductive age in Korea. However, several limitations should be considered. First, the possibility of misclassification bias cannot be ruled out, as the operational definitions used for DIP and outcomes relied on diagnostic codes and prescription-based algorithms that may not fully capture clinical diagnoses. Second, our dataset lacked several important clinical variables related to diabetes, such as educational level, dietary habits, family history of diabetes, and markers of insulin resistance. In addition, HbA1c values and data from oral glucose tolerance test were unavailable. Third, because analyses based on health examination data included only individuals who underwent the national screening program, selection bias may have occurred, as those more health-conscious or with greater access to healthcare could have been overrepresented. Nonetheless, this approach ensured standardized laboratory data acquisition and enabled reliable assessment of metabolic parameters at the population level. Fourth, postpartum surveillance in our study was assessed between 4 weeks and 1 year after delivery, whereas international guidelines recommend evaluation of glycemic status at 4 to 12 weeks postpartum. Although this approach captures glycemic testing performed within 1 year postpartum, surveillance rates based on strict adherence to guideline-recommended timing will be lower and therefore warrant cautious interpretation.

In conclusion, this nationwide study provides comprehensive and contemporary evidence on the prevalence, clinical characteristics, management, and long-term cardiovascular risk of DIP among Korean women. The findings highlight the need for strengthened preconception risk assessment and structured postpartum surveillance to reduce the burden of perinatal complications and future cardiometabolic diseases.

SUPPLEMENTARY MATERIALS

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