Rapid Rise in Rates of Diabetes During Pregnancy in Canada Not Expected to Slow

The rates of type 1, type 2, and gestational diabetes in Canada have risen steadily since 2005 and show no signs of decreasing as more women with overweight or obesity in the country continue to conceive, authors of a new study wrote in BMC Pregnancy and Childbirth.

Over the 15-year study period between 2005 and 2019 among more than 4 million hospital deliveries, the researchers reported a relative increase of 25% for T1D, 162.7% for gestational diabetes (153% including British Columbia), and 189% for T2D, all per 1000 deliveries.

The largest increases were seen among the youngest population of women and girls, aged 15 to 19 years for the 3 types of diabetes. For this age group the relative increase was 260% for GDM (including BC; 291% without BC), 330% for T2D, and 92.9% for T1D.

“Recent estimates show that the prevalence of type 2 diabetes and gestational diabetes is increasing globally. A rise in type 1 diabetes is being documented internationally in younger populations,” Chantal RM Nelson, PhD, senior epidemiologist in the maternal and infant health section at the Centre for Surveillance and Applied Research at the Public Health Agency of Canada, and colleagues wrote. “Although there are national reports on diabetes during pregnancy, few distinguish between preexisting diabetes and gestational diabetes.”

For the retrospective repeated cross-sectional study Nelson et al analyzed hospitalization data from the Canadian Institute of Health Information acute-care discharge abstract database from 2005 to 2019. Any woman aged 15 to 54 years was eligible. Maternal delivery records were linked with respective birth records and researchers calculated prevalence of T1D, T2D, and GDM. The final analysis included 4 320 778 hospital deliveries.

The research team reported variability in the prevalence of pregnancy outcomes by diabetes status, with more adverse infant outcomes among those with T1D and T2D vs those without diabetes. Adverse outcomes included major congenital anomalies, preterm birth (less than 32 weeks and between 32 and 36 weeks), large for gestational age (LGA) neonates, and stillbirth.

Among women with GDM they observed a higher prevalence of preterm birth, caesarean section, labor induction and LGA births than among those without diabetes. GDM was also associated with slightly higher rates of congenital anomalies and birth trauma, but lower rates of stillbirth compared with women without diabetes.

Regardless of type of diabetes, the prevalence of hypertension was higher among all women with any diabetes compared with those who did not have diabetes, according to the study.

Previous pregnancy was associated with a higher likelihood of GDM than first time pregnancy, the authors reported, however nulliparous mothers saw the highest relative increase in GDM (180%) compared to parous mothers (136%).

Nelson et al found a positive relationship between diabetes and maternal age for T2D and GDM with prevalence increasing with each increase in age group.

The predicted ongoing rise in rates of T1D, T2D, and GDM is linked to the trend toward an older and more obese population across Canada becoming pregnant, the authors reiterate, and they call for “continued national surveillance of DM during pregnancy to better inform and guide prevention efforts.” They emphasize that the increase in DM during pregnancy amongst the younger population warrants particular attention.”

Source
Nelson CRM, Dzakpasu S, Moore AM, et al. Diabetes mellitus in pregnancy across Canada. BMC Pregnancy Childbirth. 2924;24:349. doi:10.1186/s12884-024-06534-8