Seasonal and SARS‐CoV‐2 pandemic changes in the incidence of gestational diabetes

Cauldwell, Matthew; van‐de‐L’Isle, Yolande; Watt Coote, Ingrid; Steer, Philip J

OBJECTIVE: To test the hypothesis that there is seasonal variation in the rates of gestational diabetes (GDM) diagnosed using a 2 hour oral glucose tolerance test. DESIGN: Monthly assessment of the percentage of women screened from 1(st) April 2016 to the 31(st) December 2020 who were diagnosed as having gestational diabetes SETTING: London Teaching Hospital POPULATION: 28,128 women receiving antenatal care between April 1(st) 2016 and 31 December 2020. METHODS: Retrospective study of prospectively collected data. MAIN OUTCOME MEASURES: Proportion of women screened diagnosed as having gestational diabetes. RESULTS: The mean (SD) percentage of women diagnosed with GDM was 14.78 (2.24) in summer (June, July, August) compared with 11.23 (1.62) in winter (p < 0.001), 12.13 (1.94) in spring (p = 0.002), and 11.88 (2.67) in autumn (p = 0.003). There was a highly significant positive correlation of the percentage testing positive for GDM with the mean maximum monthly temperature (R(2) = 0.248, p < 0.001). There was a statistically significant 33.8% increase in the proportion of GDM diagnoses from June 2020 onwards, possibly related to a reduction in exercise secondary to the Covid‐19 pandemic. CONCLUSIONS: There is a 23.3% higher rate of GDM diagnoses in the warmer summer months. There has been a 33.8% rise in GDM diagnoses associated with the Covid‐19 pandemic.