Gestational diabetes and overt diabetes first diagnosed in pregnancy: characteristics, therapeutic approach and perinatal outcomes in a public healthcare referral center in Brazil

A Brazilian cohort of pregnant women with overt diabetes: analyses of risk factors using a machine learning technique

Objective

Pregnancy complicated by type 2 diabetes is rising, while data on type 2 diabetes first diagnosed in pregnancy (overt diabetes) are scarce. We aimed to describe the frequency and characteristics of pregnant women with overt diabetes, compare them to those with known pregestational diabetes, and evaluate the potential predictors for the diagnosis of overt diabetes.

Subjects and methods

A retrospective cohort study including all pregnant women with type 2 diabetes evaluated in two public hospitals in Porto Alegre, Brazil, from May 20, 2005, to June 30, 2021. Classic and obstetric factors associated with type 2 diabetes risk were compared between the two groups, using machine learning techniques and multivariable analysis with Poisson regression.

Results

Overt diabetes occurred in 33% (95% confidence interval: 29%-37%) of 646 women. Characteristics of women with known or unknown type 2 diabetes were similar; excessive weight was the most common risk factor, affecting ~90% of women. Age >30 years and positive family history of diabetes were inversely related to a diagnosis of overt diabetes, while previous delivery of a macrosomic baby behaved as a risk factor in younger multiparous women; previous gestational diabetes and chronic hypertension were not relevant risk factors.

Conclusion

Characteristics of women with overt diabetes are similar to those of women with pregestational diabetes. Classic risk factors for diabetes not included in current questionnaires can help identify women at risk of type 2 diabetes before they become pregnant.

Evolution of Gestational Diabetes Mellitus across Continents in 21st Century

Over the last few decades, several definitions of gestational diabetes mellitus (GDM) have been described. There is currently not enough research to show which way is the best to diagnose GDM. Opinions differ in terms of the optimal screening and diagnostic measures, in part due to the differences in the population risks, the cost-effectiveness considerations, and the lack of an evidence base to support large national screening programs. The basic method for identifying the disease is the measurement of glucose plasma levels which may be determined when fasting, two hours after a meal, or simply at any random time. The currently increasing incidence of diabetes in the whole population, the altering demographics and the presence of lifestyle changes still require better methods of screening for hyperglycemia, especially during pregnancy. The main aim of this review is to focus on the prevalence and modifications to the screening criteria for GDM across all continents in the 21st century. We would like to show the differences in the above issues and correlate them with the geographical situation. Looking at the history of diabetes, we are sure that more than one evolution in GDM diagnosis will occur, due to the development of medicine, appearance of modern technologies, and the dynamic continuation of research.

Overt Diabetes in Pregnancy

AIMS

Overt diabetes in pregnancy is defined as hyperglycemia first recognized during pregnancy which meets the diagnostic threshold of diabetes in non-pregnant adults. This case-based narrative review aims to describe this unique condition and discuss the potential implications for its accurate diagnosis and management.

METHODS AND RESULTS

We conducted a literature search in PubMed for relevant articles published in English language up to January 2022. Women with overt diabetes have a higher risk for adverse pregnancy outcomes and postpartum diabetes, compared to their counterparts with gestational diabetes mellitus (GDM). Such women often need aggressive management, including early and prompt initiation of insulin therapy, and a close follow-up during pregnancy and in the postpartum period. Not all pregnant women with overt diabetes have persistent diabetes in the postpartum period. Early diagnosis, especially during the first trimester, and fasting plasma glucose elevation (≥ 126 mg/dl or 7 mmol/L) at the time of initial diagnosis are predictors of postpartum diabetes.

CONCLUSIONS

Both GDM and overt diabetes in pregnancy are hyperglycemic conditions first recognized during pregnancy, but the two conditions differ in severity; the latter is a more severe form of hyperglycemia associated with worse maternal and fetal outcomes, and a higher risk of postpartum diabetes.

Prognosis Associated with Sub-Types of Hyperglycaemia in Pregnancy

We aimed to compare pregnancy outcomes in 4665 women according to the following types of hyperglycaemia in pregnancy sub-types: (i) normoglycaemia, (ii) gestational diabetes mellitus (GDM), (iii) diabetes in pregnancy (DIP), (iv) early-diagnosed (i.e., <22 weeks of gestation) GDM (eGDM), and (v) early-diagnosed DIP (eDIP). The prevalence of normoglycaemia, eGDM, eDIP, GDM, and DIP was 76.4%, 10.8%, 0.6%, 11.7%, and 0.6%, respectively. With regard to pregnancy outcomes, gestational weight gain (11.5 ± 5.5, 9.0 ± 5.4, 8.3 ± 4.7, 10.4 ± 5.3, and 10.1 ± 5.0 kg, p < 0.0001) and insulin requirement (none, 46.0%, 88.5%, 25.5%, and 51.7%; p < 0.001) differed according to the glycaemic sub-types. eGDM and eDIP were associated with higher rates of infant malformation. After adjustment for confounders, with normoglycaemia as the reference, only GDM was associated with large-for-gestational-age infant (odds ratio 1.34 (95% interval confidence 1.01-1.78) and only DIP was associated with hypertensive disorders (OR 3.48 (1.26-9.57)). To conclude, early-diagnosed hyperglycaemia was associated with an increased risk of malformation, suggesting that it was sometimes present at conception. Women with GDM, but not those with eGDM, had an increased risk of having a large-for-gestational-age infant, possibly because those with eGDM were treated early and therefore had less gestational weight gain. Women with DIP might benefit from specific surveillance for hypertensive disorders.