# Novel definition of time range and risk factors of pregnant women with gestational diabetes mellitus detected early in pregnancy a cluster analysis using clinical data of the German GestDiab cohort

## TL;DR

This study defines early gestational diabetes as occurring before 21 weeks and finds that higher pre-pregnancy weight and fasting glucose levels are linked to early-onset cases.

## Contribution

The paper introduces a novel definition of early gestational diabetes and identifies specific risk factors through clustering and predictive modeling.

## Key findings

- Early gestational diabetes is defined as occurring before 21 weeks of gestation.
- Women with early GDM had higher pre-pregnancy BMI and fasting glucose levels compared to standard GDM cases.
- A predictive model achieved an area under the curve of 0.83 for identifying early GDM.

## Abstract

Gestational diabetes mellitus (GDM) is the most common pregnancy complication worldwide, leading to a variety of short and longterm complications for both mother and child. International screening and diagnostic recommendations remain disputed and incoherent. A high proportion of women with GDM can be detected early in pregnancy. However, there is no consensus about diagnosis of GDM in early pregnancy. In this study, we aimed to detect a clear time frame for early GDM (eGDM). Based on these results, we compared the characteristics of early vs standard GDM.

In this secondary data analysis all data were sourced from diabetes specialist practices, from Germany and were collected between the years of 2018–2021.We applied k-means clustering to create two homogenous groups, identifying an early and a standard GDM cohort. Subsequently, we analyzed presented data regarding its association with early gestational diabetes (eGDM) and standard GDM (sGDM).Finally, a prediction model was developed using a set of nine variables. Odds ratios of each variable served as an independent indicator on the individual effect of each factor.

Our dataset included 18,495 pregnancies complicated by gestational diabetes. The decision boundary through our k-means analysis was determined as 20.88 week of gestation. Both groups had a mean age of 33 years of age. Women with early gestational diabetes presented higher pre-pregnancy body weight (86.6 kg vs. 76.8 kg) and higher pre-pregnancy BMI (31.1 vs. 27.9 kg/m2) and with an average weight difference of 9.8 kg. Fasting plasma glucose differed significantly between both groups (eGDM: 98.1 mg/dl [5,4 mmol/l] vs. sGDM 94.7 mg/dl [5,3 mmol/l]). The logistic regression model for eGDM achieved an area under the curve of 0.83.

We defined early gestational diabetes as gestational diabetes occurring before 21st week of gestation. Fasting plasma glucose with a threshold value of 98 mg/dl [5,4 mmol/l] could be an appropriate tool for screening.

GestDiab is listed in the German Trial Registry (https://registersuche.bqs.de/search.php)

The online version contains supplementary material available at 10.1186/s13098-025-02000-3.