Progression to type 2 diabetes in women with a known history of gestational diabetes: systematic review and meta-analysis
Published on May 13, 2020in BMJ30.223
· DOI :10.1136/BMJ.M1361
Objective: To estimate and compare progression rates to type 2 diabetes mellitus (T2DM) in women with gestational diabetes mellitus (GDM) and healthy controls. Design: Systematic review and meta-analysis.Data Sources: Medline and Embase from January 2000 to December 2019, studies published in the English language and conducted on humans.Eligibility Criteria for Selecting Studies: Observational studies investigating progression to T2DM. Inclusion criteria: post-partum follow-up for at least 12 months; incident physician-based diabetes diagnosis; T2DM reported as a separate outcome rather than combined with impaired fasting glucose or impaired glucose tolerance; and studies with both a GDM and a control group. Results: This was a meta-analysis of 18 studies, assessing a total of 1,126,959 individuals (55,544 women with GDM and 1,071,415 controls). Data were pooled using random effects models, and heterogeneity was assessed using the I2 statistic. The pooled relative risk (RR) for T2DM cumulative incidence between GDM participants and controls was estimated. Reasons for between-study heterogeneity were investigated by subgroup and meta-regression analyses. Publication bias was assessed using funnel plots and studies were deemed to have a low risk of bias (p= 0.405 and p= 0.973). The overall RR for T2DM was almost ten times higher in women with previous GDM compared to healthy controls (RR: 9.78, 95% confidence interval 6.74 to 14.20, p<0.001). In populations of women with previous GDM, the cumulative incidence of T2DM was higher in a mixed ethnicity or a predominantly non-white population, compared to a white population (16.3% & 15.6% vs 9.4% respectively). The cumulative incidence of T2DM in women affected by GDM was highest in the first decade post-pregnancy. Meta-regressions demonstrated that the study effect size was not significantly associated with mean study age, body-mass index, publication year and length of follow-up.Conclusions: Women with a history of GDM have a nearly tenfold higher risk of developing T2DM compared to those with a normoglycemic pregnancy. The magnitude of this risk highlights the importance of intervening to prevent the onset of T2DM, particularly in the early years post-pregnancy.