RELATIONSHIP BETWEEN PREVALENCE OF GESTATIONAL DIABETES MELLITUS AND PERIOD OF GESTATION: EVIDENCE FROM A RANDOMIZED CONTROLLED TRIAL

Abstract

Background: Gestational diabetes mellitus (GDM) is typically diagnosed between 24–28 weeks of gestation when insulin resistance peaks. However, its onset and detection can occur across a range of gestational periods, raising questions about variations in prevalence by gestational age.

Objective: To evaluate the distribution and proportion of GDM diagnoses relative to different gestational age groups at time of presentation and recruitment in a Himachal Pradesh–based randomized controlled trial.

Methods: Sixty women diagnosed with GDM based on IADPSG criteria were enrolled in a double-blind randomized placebo-controlled clinical trial. Participants were grouped according to gestational age at enrollment. Chi-square analysis was used to assess the relationship between period of gestation and distribution of GDM cases.

Results: A majority of participants (35%) were diagnosed during the gestational window of 28+1 to 32 weeks, followed by 24+1 to 28 weeks (21.7%). The earliest diagnoses (<20 weeks) accounted for only 15% of cases. The gestational age distribution did not significantly differ between treatment groups (p = 0.154), but late second to early third trimester saw the highest case detection.

Conclusion: The distribution of GDM diagnoses in this cohort closely aligns with the physiologic trajectory of insulin resistance during pregnancy, peaking around the late second trimester. This supports routine screening for GDM around 24–28 weeks, but highlights the importance of early screening in high-risk populations.