Both type 1 and type 2 diabetes are associated with greater risk of a variety of cancers. However, the association between gestational diabetes mellitus (GDM) and risk of cancer has so far not been well addressed. This study aimed to summarize the epidemiological evidence of the association between GDM and subsequent risk of cancer.

PubMed and Embase databases were searched for relevant studies, and a random-effects model was used to calculate the summary relative risks (RRs) along with the corresponding 95% confidence intervals (CIs).

A total of 17 observational studies were selected, comprising 7 case–control and 10 cohort studies. Pooled effect estimates retrieved from these 17 studies showed that GDM was associated with an increased risk of breast cancer in Asia (pooled RR: 1.31, 95% CI: 1.01–1.70), but not in other regions, and also with thyroid cancer (RR: 1.28, 95% CI: 1.16–1.42), stomach cancer (RR: 1.43, 95% CI: 1.02–2.00) and liver cancer (RR: 1.27, 95% CI: 1.03–1.55). However, GDM was not associated with any increased risk of colon (RR: 1.41, 95% CI: 0.90–2.21), colorectal (RR: 1.16, 95% CI: 0.95–1.41), ovarian (RR: 1.14, 95% CI: 0.90–1.44), cervical (RR: 1.02, 95% CI: 0.81–1.29), pancreatic (RR: 3.49, 95% CI: 0.80–15.23), brain and nervous system (RR: 1.26, 95% CI: 0.80–1.97), blood (leukaemia, RR: 0.77, 95% CI: 0.45–1.30), endometrial (RR: 0.77, 95% CI: 0.20–2.98), skin (RR: 1.13, 95% CI: 0.81–1.59) or urological (RR: 0.98, 95% CI: 0.73–1.31) cancers.

GDM is associated with a greater risk of cancer in women, including breast, thyroid, stomach and liver cancers. However, further investigation is nonetheless warranted.