Overdiagnosis of gestational diabetes mellitus during Ramadan: a retrospective population-based study in Catalonia, Spain

Abstract

Background Fasting during Ramadan is widely practiced, with nearly a quarter of the world’s population identifying as Muslim. However, it remains unclear whether Ramadan-associated practices influence gestational diabetes mellitus (GDM) diagnosis. The aim of our study was to investigate the possible association between the practice of Ramadan and the outcome of diagnostic tests for GDM.

Methods We performed a retrospective study using the SIDIAP primary care database in Catalonia, Spain, covering 2010–2019. We included 35,054 pregnancy episodes screened for GDM in women aged 18–50 years without prior diabetes from Muslim-majority countries (MMC). Women from the MMC group were matched by calendar age (1:1) with women from non-Muslim-majority countries (control group). GDM incidence and plasma glucose values from diagnostic testing were compared between Ramadan and non-Ramadan periods in both groups. General linear and mixed models were applied to assess whether the Ramadan period was associated with increased GDM diagnosis and glucose values.

Results In the control group, GDM incidence was similar during Ramadan and non-Ramadan periods (5.57% vs. 5.52%; p = 0.930). In contrast, the MMC group showed a significantly higher GDM rate during Ramadan (12.8% vs. 8.84%; p < 0.001). The adjusted regression model, for maternal age, BMI, number of pregnancies, blood pressure, and socioeconomic status, confirmed that the RAM period was associated with a higher risk of GDM in women from Muslim countries (MMC group) than those in the control group (OR for interaction term = 1.51; 95% CI, 1.26–1.81).

Conclusions Among women from Muslim-majority countries, the rate of GDM diagnosis was higher during Ramadan. This finding may reflect a potential influence of fasting or other Ramadan-related factors on glucose testing and diagnostic practices. Clinicians should consider the possible impact of Ramadan timing when scheduling GDM screening. Further studies are warranted to confirm these observations and explore underlying mechanisms.