# Low prevalence of GCK gene mutations in Chinese patients with gestational diabetes mellitus

## TL;DR

This study found that GCK gene mutations are rare in Chinese women with gestational diabetes, suggesting that screening based on fasting blood glucose may not be effective for identifying GCK-MODY in this population.

## Contribution

The study demonstrates the limited utility of FBG-based GCK-MODY screening in Chinese gestational diabetes patients.

## Key findings

- Only 1.9% of Chinese GDM patients had rare GCK variants.
- No confirmed GCK-MODY cases were found among variant carriers.
- Fasting glucose thresholds may not reliably distinguish GCK-MODY from GDM.

## Abstract

•Screened 177 Chinese GDM women (FBG ≥5.1 mmoL/L) for GCK variants.•Identified 8 rare GCK variants in 9 individuals (1.9 % prevalence).•No confirmed GCK-MODY cases found among variant carriers.•Limited utility of FBG-based GCK-MODY screening in Chinese GDM.

Screened 177 Chinese GDM women (FBG ≥5.1 mmoL/L) for GCK variants.

Identified 8 rare GCK variants in 9 individuals (1.9 % prevalence).

No confirmed GCK-MODY cases found among variant carriers.

Limited utility of FBG-based GCK-MODY screening in Chinese GDM.

Accumulating evidence suggests maturity onset diabetes of the young (MODY) caused by GCK gene mutations (GCK-MODY) is often misdiagnosed as Gestational Diabetes Mellitus (GDM) in pregnant women. This study investigated the prevalence and diagnostic value of GCK gene mutations in Chinese GDM patients.

A retrospective analysis was conducted on 3394 pregnant women undergoing prenatal care or delivery at Beijing Jishuitan Hospital between April and December 2019. GDM was diagnosed in 474 women (14.0%) using the International Association of Diabetes and Pregnancy Study Groups (IADPSG, 2010) criteria via a 75 g Oral Glucose Tolerance Test (OGTT). Among these, 177 GDM patients with fasting blood glucose ≥5.1 mmoL/L underwent targeted GCK gene sequencing.

Targeted sequencing identified eight rare GCK variants in nine individuals. None of the variant carriers met definitive diagnostic criteria for GCK-MODY. The prevalence of rare GCK variants in the screened GDM subgroup was 1.9% (9/474).

The low prevalence (1.9%) of rare GCK variants and absence of confirmed GCK-MODY cases indicate limited utility of fasting glucose-based screening for GCK-MODY in Chinese GDM populations. These findings highlight challenges in distinguishing GCK-MODY from GDM through conventional glucose thresholds.