Indications for the Postpartum Oral Glucose Tolerance Test

Data from the GestDiab registry

Background: Gestational diabetes mellitus (GDM) affects more than 50 000 pregnant women in Germany every year. In postpartum diabetes screening, a 75 g oral glucose tolerance test (OGT) is recommended. This is time-consuming and can have side effects, and only 40% of mothers take it. The determination of pre-test probabilities might obviate the need for OGT except in women who are at particular risk.

Methods: We analyzed 5444 cases of GDM from the GestDiab registry over the period 2015–2019. The pretest probabilities of a postpartum diagnosis of diabetes mellitus (DM) or prediabetes were calculated on the basis of clinical variables including postpartum venous fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c).

Results: In 0.77% of mothers with a history of GDM in whom DM was not detected by FPG or HbA1c, postpartum DM was diagnosed on the basis of the 2-hour value in the OGT. Individual estimation of the pre-test probability of a diagnosis by OGT of postpartum DM or prediabetes was possible with the aid of the FPG and HbA1c values and clinical predictors including insulin treatment during pregnancy, obesity, GDM diagnosed before 24 weeks of gestation, age over 35, and a 1-hour value in the diagnostic OGT during pregnancy of 180 mg/dL (10.0 mmol/L) or above. The pretest probability of postpartum DM in the study group ranged from 0.11% to 4.17%, and that of postpartum prediabetes from 6.4% to 16.3%.

Conclusion: The probability of a diagnosis of postpartum diabetes by OGT after GDM can be estimated in postpartum screening on the basis of various parameters. This enables risk-adapted counseling of the affected women along with a long-term strategy for diabetes prevention and follow-up. The findings of our study should be verified by further research.

Postpartum diabetes screening for gestational diabetes mellitus (GDM) includes postpartum diagnostic tests, informing the mother regarding her long-term cardiovascular prognosis and risk for diabetes mellitus (DM), and her transition to long-term follow-up. On the one hand, this is to detect the development of DM in a timely manner, and on the other, to provide mothers with ongoing and targeted motivation to maintain a healthy lifestyle in the long term, based on their individual risk and clinical findings. Behavioral changes—in particular weight reduction, sufficient physical activity, and a healthy diet—reduce the risk of cardiovascular disease and DM in this risk group as well (1).

According to the GDM guideline of the German Association of Scientific Medical Societies (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften, AWMF), an oral glucose tolerance test (OGT) is indicated in all women 6–12 weeks postpartum following a pregnancy with GDM (2). “In this case, the normal values for the OGT outside pregnancy with blood glucose determinations while fasting and 2 h after exercise in accordance with the WHO guidelines apply” (3). According to the German Institute for Quality Assurance and Transparency in the Healthcare Sector (Institut für Qualitätssicherung und Transparenz im Gesundheitswesen, IQTIG), this applied to 51,147 (6.81%) of a total of 750,996 pregnancies in Germany in 2019 (4).

Postpartum OGT is intended to determine whether DM or prediabetes, that is, impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG), is present. In addition, long-term follow-up and prevention should be discussed with affected women, since they have a significantly higher risk for developing DM and cardiovascular disease in the future (5, 6, 7, 8, 9, 10, 11). However, not only in our registry but also internationally and consistently over the years, only around 40% of affected women take up the offer of postpartum diabetes screening (12, 13, 14, 15).

This is possibly due to the fact that patients need to spend a significantly longer period of time in the physician’s practice for an OGT, meaning that a lot of resources are used by the families concerned and the practices. On the other hand, the test can cause significant circulatory stress, vomiting, and reactive hypoglycemia (12%) (16). Furthermore, during the pandemic, it was clear that several people staying in one room for a long period of time posed an avoidable risk of infection. It is possible that the risks and the time involved could reduce mothers’ acceptance of the postpartum OGT.

Therefore, the question arises as to whether a proportion of mothers can be offered an alternative approach that saves resources and reduces the number of OGTs.

The determination of hemoglobin A1c (HbA1c) alone 6–12 weeks postpartum is not recommended for screening (2, 3). Blood loss and the high proportion of younger erythrocytes following childbirth can result in falsely low HbA1c levels, meaning that a low HbA1c cannot rule out DM. Nevertheless, an HbA1c ≥ 6.5% (≥ 48 mmol/mol) and/or a fasting plasma glucose (FPG) ≥ 126 mg/dL (≥ 7.0 mmol/L) establishes the diagnosis of DM (3, 17).

The question also arises regarding the extent to which the detection of IGT is necessary for screening following a pregnancy with GDM. On the one hand, this has high predictive value for conversion to DM, while on the other, the risk of diabetes in subsequent years can already be estimated on the basis of the previous GDM, breastfeeding behavior, and an assessment of additional parameters (12, 18, 19).

Methods

GestDiab is an ongoing registry study conducted by winDiab, the scientific institute of office-based diabetologists in Germany (13). Between 2008 and 2023, it documented the data for 60,000 pregnancies with GDM or DM. The data taken from routine care were pseudonymously entered in an online database by the participating study centers (German diabetes specialized practices and diabetes outpatient departments). Written consent was obtained from the women involved.

In the period 2015–2019, 3,739,874 pregnancies in Germany were included in the national obstetrics evaluation conducted by the IQTIG, of which 220,132 (5.9%) had GDM (4, 20, 21). For the same period, 25,500 cases of GDM were documented Germany-wide in the GestDiab registry (11.6%).

In 1,350 of these, manifest DM had already been diagnosed during pregnancy (5.3%) and were excluded from further analysis. For the current research question, data from 24,150 GDM pregnancies from 2015 to 2019 were examined. A total of 9538 (39.5%) women presented for postpartum diabetes screening.

Further cases were excluded due to incomplete data sets with regard to the research question (n = 3954) and due to the diagnosis of DM based on FPG or HbA1c (n = 140).

Finally, the data of 5444 mothers were analyzed (Figure 1). This involved determining the frequency and probability of a pathological OGT result, differentiated according to relevant registry variables. When selecting these variables, which we refer to here as predictors, we considered the literature with related research questions as well as availability in routine care and in the registry data (Table 1) (12, 22, 23, 24). The pre-test probability for the diagnosis of DM by OGT was calculated for the following five predictors: insulin therapy during pregnancy, obesity, GDM diagnosis before the 24th week of gestation (GW), age over 35, 1-h value in the diagnostic OGT during pregnancy ≥ 180 mg/dL/≥ 10.0 mmol/L—and for the number of these present in each patient.

Figure 1

A selection of cases for this analysis

Table 1

OGT pre-test probabilities of DM or IGT (with or without IFG) based on parameters during pregnancy

The relative risk (RR) was calculated as a quotient of pre-test probabilities. Confidence intervals were calculated using the Wilson interval.

In this way, we assessed the constellation in which an OGT is particularly important due to the high pre-test probability or in which it may be obviated.

We also determined pre-test probabilities taking into consideration FPG and HbA1c levels measured at postpartum presentation (Tables 2 and 3).

Results

An analysis of the data sets on postpartum screening showed that manifest DM had already been diagnosed in 2.5% of mothers (140/5584) based on FPG (≥ 126 mg/dL/≥ 7.0 mmol/L) or HbA1c (≥ 6.5%/≥ 48 mmol/mol) (2, 3). These were excluded from further calculations, meaning that the following analyses are based on 5444 data sets.

A further 42/5444 (0.77%) of the mothers were diagnosed with DM based only on the 2-h level in the OGT (≥ 200 mg/dL/≥ 11.1 mmol/L), while 534/5 444 (9.8%) were diagnosed with IGT (2-h glucose in the OGT of 140–199 mg/dL/7.8–11.0 mmol/L) (Table 1).

The probability that manifest DM is diagnosed during postpartum diabetes screening by OGT in the case of normal FPG (< 100 mg/dL/< 5.6 mmol/L) and normal HbA1c (< 5.7%/< 39 mmol/mol) (2-h level in the OGT ≥ 200 mg/dL/≥ 11.1 mmol/L) is 0.33%. For isolated impaired glucose tolerance (2-h value in the OGT of 140–199 mg/dL/7.8–11.0 mmol/L), it is 6.5%. In the case of an FPG of 100–125 mg/dL/5.6–6.9 mmol/L and/or an HbA1c of 5.7–6.4%/39–47 mmol/mol, that is to say, in the prediabetic range, the probability of DM ranges between 0.84% and 2.18% and the IGT probability between 12.0% and 22.8% (Table 2). To expand on this estimate, we investigated which other factors effect the result of the OGT (Table 3).

Table 2

OGT pre-test probabilities of DM or IGT (with or without IFG) with postpartum measurements and information on breastfeeding

Table 3

OGT pre-test probability of DM or IGT (with or without IFG) in postpartum diabetes screening depending on number of predictors and fasting plasma glucose (FPG), number (% and 95% confidence interval)

The following parameters have proved not only to be particularly informative but are also always available in routine care: insulin therapy during pregnancy (RR 3.64 compared to no insulin therapy), a body mass index (BMI) of over 30 kg/m² (RR 1.58 compared to normal weight), GDM diagnosis before the 24th GW (RR 1.57 compared to diagnosis in the 24th–28th GW), 1-h value in the diagnostic OGT of ≥ 180 mg/dL/≥ 10.0 mmol/L (RR 8.27 compared to < 180 mg/dL/< 10.0 mmol/L), and age over 35 years (RR 1.50 compared to under 35). Therefore, these are referred to below as predictors for the diagnosis of DM by postpartum OGT.

Figure 2a shows how frequently zero to five predictors are seen in the women examined: Almost 50% have no or only one predictor. The pre-test probabilities of additional influencing factors are given in Tables 1 and 2.

Figure 2

Predictors for the diagnosis of manifest DM in the postpartum OGT (n = 5444, GestDiab 2015–2019)

The probability of identifying DM or IGT by OGT increases with the number of these predictors and can already be estimated at the end of pregnancy and before the postpartum OGT (Table 1 and Figure 2b). If no predictors are present, the probability of DM is 0.22%, with two predictors 0.70%, and with five predictors 4.17% (Figure 2b).

Finally, we calculated a combination of the number of predictors with the FPG. At an FPG of < 100 mg/dL (< 5.6 mmol/L) and with less than two predictors, the probability of diagnosing DM by 75-g OGT is only 0.11%. This applies to 1784 (or 33%) of 5444 women. If there are two or more risk factors at an FPG of 100–125 mg/dL/5.6–6.9 mmol/L, it is 2.08%. This applies to 1204 (or 22%) of 5444 women (Table 3).

Discussion

The aim of this study was to investigate whether it would be possible to dispense with some OGTs in the postpartum period in a risk-adapted manner.

The time frame recommended in guidelines (6–12 weeks postpartum) for diabetes screening by OGT (2) is less important than the need to establish early, appropriate maternal follow-up in general. It is essential that this is carried out prior to a further pregnancy in order to avoid hyperglycemia at the time of conception. The postpartum OGTs evaluated here took place up to 12 months following birth.

Studies show that: Even if DM is not diagnosed immediately postpartum, the risk of it developing in subsequent years is 7.5–10 times higher (9, 25). A woman’s individual risk can be estimated based on clinical parameters and diagnostic parameters during pregnancy (5, 26). It has also been shown that these women have an up to two-fold higher cardiovascular risk (8, 11). This is true even if they do not develop DM (7, 8, 11, 27, 28). Therefore, the motivation to follow a healthy lifestyle must be risk-adapted for all women that have experienced GDM. At the same time, their cardiovascular risk needs to be considered in medium- and long-term follow-up care and prevention.

However, internationally, fewer women present for postpartum screening than is desirable (12, 15). One possible obstacle for mothers with young children to care for is the high time requirement for the appointment: at least 3 h for the OGT and consultation.

Already during pregnancy with GDM, it is possible to identify women who are at high risk of manifest DM immediately postpartum. With this knowledge, these women can be motivated particularly intensively to take a postpartum OGT. The five predictors mentioned above are recorded in routine care and enable a rapid assessment of the risk of postpartum DM in routine practice. The risk significantly increases with the number of predictors: from 0.2% without predictors to 4.2% with five predictors (Figure 2b).

With the FPG and HbA1c values, one can additionally extend the calculation of the pre-test probability in postpartum diabetes screening. In 2.5% (n = 144) of cases, DM had already been diagnosed by determining FPG and/or HbA1c if values had been confirmed by a second measurement (3). Thus, it would have been possible to dispense with an OGT. For the remaining women (n = 5444), the pre-test probability calculated from the registry data for the OGT to detect DM using the 2-h value alone is only 0.77 % (1:  130). This can be further differentiated by various known predictors to between 0.11 and 4.17% (= 1: 909 to 1: 24).

The factors that most influence the risk of postpartum DM or IGT proved to be the level of FPG and HbA1c at postpartum screening, HbA1c and a 1-h value of ≥ 180 mg/dL/≥ 10 mmol/L in the diagnostic OGT during pregnancy, the diagnosis of GDM before the 24th GW, insulin therapy during pregnancy, and to a lesser degree, older age, diabetes in first-degree relatives, and obesity (Tables 1, 2). These finding are in line with the results obtained by Schaefer-Graf et al. in 2009: The 1-h value in diagnostic OGT during pregnancy (here, ≥ 200 mg/dL/≥ 11.1 mmol/L) correlated highly significantly with the result of postpartum OGT (12).

IGT (2-h value in the OGT, 140–199 mg/dL/7.8–11 mmol/L) indicates prediabetes and an increased risk for progression to manifest DM of 3–14% per year (14, 15, 16). In this particular situation, the detection of IGT does not change the therapeutic or preventive implications, given that previous GDM alone requires consistent long-term follow-up (22, 29, 30).

If, after measuring FPG and HbA1c, one knows that the pre-test probability is low, there is a rational basis for the possible decision not to perform an OGT. Thus, as part of the participatory decision-making process, screening can be structured by the diabetes team and the affected woman in a risk-adapted and tailored manner.

Our proposal for postpartum screening following GDM is an individualized, risk-stratified approach: All women undergo point-of-care testing (POCT) to determine FPG and HbA1c. If this reveals DM, one can dispense with an OGT. However, it is still necessary to take a second measurement of an individual pathological value. With the other women, we discuss the individual, data-based probability of a diabetes diagnosis by OGT (1: 909 –1: 24, see above). A joint decision is then made as to whether an OGT should be performed in line with the guidelines or whether screening should be limited to measuring FPG and HbA1c. The pre-test probability at which an OGT is carried out based on participatory decision-making depends on multiple factors, such as a mother’s need for a sense of security. In addition, the higher the estimated metabolic risk, the earlier the next metabolic test should be scheduled in long-term follow-up.

If an OGT were offered only in the case of two or more risk factors and an FPG > 100 mg (> 5.6 mmol/L), that is, at a risk for the diagnosis of DM of at least 2.08%, this could save around three quarters of women from undergoing an OGT (Table 3). Not only would this approach relieve the burden on young mothers, it would also ease the burden on medical practices by reducing the number of OGTs.

Resources freed up by this approach should be used to persuade women at high risk to participate in postpartum diabetes screening by OGT. All pregnant women, on the other hand, should be advised to breastfeed, particularly since breastfeeding also reduces the long-term risk of diabetes (10).

The focus of internal medicine and diabetology consultations postpartum must be on initiating a long-term follow-up and prevention strategy as well as providing advice on a healthy lifestyle.

Limitations

The data come from the real-life situation of diabetes care in Germany—from specialized diabetes practices and outpatient departments that are voluntarily participating in the GestDiab registry. This brings with it not only strengths, such as a high number of cases and representativeness, but also limitations.

These possibly particularly engaged practitioner networks with the referring gynecological practices may, for example, have implemented GDM screening especially efficiently in the case of risk factors before the 24th GW. This could have led to selection that influenced pre-test probabilities.

Only around 40% of GDM patients documented in the registry could be analyzed, since only these patients had accepted the invitation to postpartum screening. Another analysis of the registry data showed that women treated with insulin during pregnancy as well as women who were older attended postpartum screening somewhat more frequently (31). In our estimation, the distortion caused by this is low for the present analysis.

According to the current guidelines, the diagnosis of DM requires two pathological values: FPG, values from a 75-g OGT, or HbA1c measurement can be used to this end (2, 3). In the case of only one pathological glucose measurement, this must be confirmed at some other time, but is not documented in the GestDiab register. We consider the conceivable bias resulting from this to be of little relevance since we assume that a specialized diabetes practice would not dispense with a confirmatory value for the diagnosis of DM.

Independent studies to confirm our results in other collectives and healthcare systems are needed.

Acknowledgments

We would like to thank all the specialized diabetes practices and diabetes outpatient departments that have documented their cases as part of the GestDiab project for their engagement and resources.

Conflict of interest statement

HA is a member of the German Diabetes Association (Deutsche Diabetes Gesellschaft, DDG), spokesperson for the DDG Working Group on Diabetes and Pregnancy (AG Diabetes und Schwangerschaft), a member of winDiab (Steering Committee of the GestDiab Registry), and a member of the North Rhine Professional Association of Specialized Diabetology Practices (Berufsverband der diabetologischen Schwerpunktpraxen Nordrhein). The GestDiab Working Group was part of the GestDina_basic project, which was funded by the Innovation Fund from 9/2019 to 2/2023 (Grant No. 01VSF18009).

MK is Managing Director of winDiab as well as a member of the DDG, the Diabetes and Pregnancy Working Group of the DDG, and the North Rhine Professional Association of Specialized Diabetology Practices. He received honoraria from ADS e. V. for a presentation on gestational diabetes.

JK and DW declare that no conflict of interest exists.

Manuscript received on 5 September 2023, revised version accepted on

9 February 2024.

Translated from the original German by Christine Rye.

Corresponding author
Dr. med. Heinke Adamczewski
Gemeinnützige winDiab GmbH
GestDiab Arbeitsgruppe
Geranienweg 7a
41564 Kaarst, Germany

Cite this as:
Adamczewski H, Weber D, Klein J, Behling M, Kaltheuner M: Indications for the postpartum oral glucose tolerance test—data from the GestDiab registry. Dtsch Arztebl Int 2024; 121: 251–7. DOI: 10.3238/arztebl.m2024.0034

References

1. Aroda VR, Christophi CA, Edelstein SL, et al.: The effect of lifestyle intervention and metformin on preventing or delaying diabetes among women with and without gestational diabetes: the Diabetes Prevention Program outcomes study 10-year follow-up. J Clin Endocrinol Metab 2015; 100: 1646–53

2. Schaefer-Graf UM, Laubner K, Hummel M, Gembruch U: S3-Leitlinie Gestationsdiabetes mellitus (GDM), Diagnostik, Therapie und Nachsorge, 2. Auflage: AWMF-Registernummer 057–008 (2. Auflage). AWMF 2018

3. Schleicher E, Gerdes C, Petersmann A, et al.: Definition, Klassifikation und Diagnostik des Diabetes mellitus: Update 2021. Diabetologie 2021; 16 (Suppl 2): S110–S8

4. IQTIG: Bundesauswertung zum Erfassungsjahr 2019 Geburtshilfe Qualitätsindikatoren und Kennzahlen: 2018–2019, 2020. Available from www.iqtig.org/downloads/auswertung/2019/16n1gebh/QSKH_16n1-GEBH_2019_BUAW_V02_2020-07-14.pdf (last accessed on 9 January 2024).

5. Song C, Lyu Y, Li C, et al.: Long-term risk of diabetes in women at varying durations after gestational diabetes: a systematic review and meta-analysis with more than 2 million women. Obes Rev 2018;19: 421–9

6. Daly B, Toulis KA, Thomas N, et al.: Increased risk of ischemic heart disease, hypertension, and type 2 diabetes in women with previous gestational diabetes mellitus, a target group in general practice for preventive interventions: a population-based cohort study. PLoS Med 2018; 15: e1002488

7. Gunderson EP, Sun B, Catov JM, et al.: Gestational diabetes history and glucose tolerance after pregnancy associated with coronary artery calcium in women during midlife: The CARDIA Study. Circulation 2021; 143: 974–87

8. Yu Y, Soohoo M, Sørensen HT, Li J, Arah OA: Gestational diabetes mellitus and the risks of overall and type-specific cardiovascular diseases: a population- and sibling-matched cohort study. Diabetes Care 2022; 45: 151–9

9. Vounzoulaki E, Khunti K, Abner SC, Tan BK, Davies MJ, Gillies CL: Progression to type 2 diabetes in women with a known history of gestational diabetes: systematic review and meta-analysis. BMJ 2020; 369: m1361

10. Ziegler AG, Wallner M, Kaiser I, et al.: Long-term protective effect of lactation on the development of type 2 diabetes in women with recent gestational diabetes mellitus. Diabetes 2012; 61: 3167–71

11. Kramer CK, Campbell S, Retnakaran R: Gestational diabetes and the risk of cardiovascular disease in women: a systematic review and meta-analysis. Diabetologia 2019; 62: 905–14

12. Schaefer-Graf UM, Klavehn S, Hartmann R, et al.: How do we reduce the number of cases of missed postpartum diabetes in women with recent gestational diabetes mellitus? Diabetes Care 2009; 32: 1960–4

13. Adamczewski H, Weber D, Faber-Heinemann G, Heinemann L, Kaltheuner M: GestDiab – Praxisregister diabetischer Schwangerschaften und DDG-Förderung: Ergebnisse einer Evaluierung von mehr als 11.000 Schwangerschaften mit Gestationsdiabetes. Diabetologie und Stoffwechsel 2016; 11: DOI:10.1055/s-0036–1580921

14. Olesen CR, Nielsen JH, Mortensen RN, Bøggild H, Torp-Pedersen C, Overgaard C: Association between follow-up screening after gestational diabetes and early detection of diabetes—a register based study. BMC Public Health 2014: 14: 841

15. D‘Amico R, Dalmacy D, Akinduro JA, et al.: Patterns of postpartum primary care follow-up and diabetes-related care after diagnosis of gestational diabetes. JAMA Netw Open 2023; 6: e2254765

16. Quansah DY, Giorgi S de, Le Dizes O, et al.: Reactive hypoglycaemia during the OGTT after gestational diabetes mellitus: metabolic implications and evolution. Diabet Med 2022; 39: e14920

17. Ozarda Y, Sikaris K, Streichert T, Macri J: Distinguishing reference intervals and clinical decision limits—a review by the IFCC Committee on Reference Intervals and Decision Limits. Crit Rev Clin Lab Sci 2018; 55: 420–31

18. Köhler M, Ziegler AG, Beyerlein A: Development of a simple tool to predict the risk of postpartum diabetes in women with gestational diabetes mellitus. Acta Diabetol 2016; 53: 433–7

19. Piwonska-Solska B, Pach DP, Gilis-Januszewska AGJ, Hubalewska-Dydejczyk AHD: Risk factors of conversion from IGT and IFG to diabetes type 2. Endocrine Abstracts 2011; 26: 725.

20. IQTIG: Bundesauswertung zum Erfassungsjahr 2016 Geburtshilfe Qualitätsindikatoren und Kennzahlen: 2015–2016. Available from www.iqtig.org/downloads/auswertung/2016/16n1gebh/QSKH_16n1-GEBH_2016_BUAW_V02_2017-07-12.pdf (last accessed on 5 January 2024).

21. IQTIG: Bundesauswertung zum Erfassungsjahr 2017 Geburtshilfe Qualitätsindikatoren und Kennzahlen: 2016–2017. Available from www.iqtig.org/downloads/auswertung/2017/16n1gebh/QSKH_16n1-GEBH_2017_BUAW_V02_2018-08-01.pdf (last accessed on 5 January 2024).

22. Lobner K, Knopff A, Baumgarten A, et al.: Predictors of postpartum diabetes in women with gestational diabetes mellitus. Diabetes 2006; 55: 792–7

23. Rayanagoudar G, Hashi AA, Zamora J, Khan KS, Hitman GA, Thangaratinam S: Quantification of the type 2 diabetes risk in women with gestational diabetes: a systematic review and meta-analysis of 95,750 women. Diabetologia 2016; 59: 1403–11

24. Schäfer-Graf U, Xiang A, Buchanan T, Berkowitz K, Kjos S, Vetter K: Risikofaktoren für einen postpartal persistierenden Diabetes nach Schwangerschaften mit Gestationsdiabetes. Geburtsh Frauenheilk 1998; 58: 640–6

25. Bellamy L, Casas JP, Hingorani AD, Williams D: Type 2 diabetes mellitus after gestational diabetes: a systematic review and meta-analysis. Lancet 2009; 373: 1773–9

26. KIM C, Newton KM, Knopp RH: Gestational diabetes and the incidence of type 2 diabetes: a systematic review. Diabetes Care 2002; 25: 1862–8

27. Retnakaran R, Shah BR: Glucose screening in pregnancy and future risk of cardiovascular disease in women: a retrospective, population-based cohort study. Lancet Diabetes Endocrinol 2019; 7: 378–84

28. Rathmann W, Meisinger C: Wie häufig ist Typ-2-Diabetes in Deutschland? Diabetologe 2010; 6: 170–6

29. Edelstein SL, Knowler WC, Bain RP, et al.: Predictors of progression from impaired glucose tolerance to NIDDM: an analysis of six prospective studies. Diabetes 1997; 46: 701–10

30. Meier JJ, Nauck MA, Schmidt WE, Gallwitz B: Diagnose einer eingeschränkten Glukosetoleranz und Diabetesprävention: Kann die Diabetes-Epidemie aufgehalten werden? Dtsch Arztebl 2002; 99: A–3182.

31. Linnenkamp U, Greiner GG, Haastert B, et al.: Postpartum screening of women with GDM in specialised practices: data from 12,991 women in the GestDiab register. Diabet Med 2022; 39: e14861