Day Care Attendance and Risk of Type 1 Diabetes: A Meta-Analysis and Systematic Review.

Importance: A meta-analysis published in 2001 suggested that exposure to infections measured by day care attendance may be important in the pathogenesis of type 1 diabetes. Several new studies on the topic have since been published.

Objective: To investigate the association between day care attendance and risk of type 1 diabetes and to include all available literature up to March 10, 2024.

Data sources: Data from PubMed and Web of Science were used and supplemented by bibliographies of the retrieved articles and searched for studies assessing the association between day care attendance and risk of type 1 diabetes.

Study selection: Studies that reported a measure of association between day care attendance and risk of type 1 diabetes were included.

Data extraction and synthesis: Details, including exposure and outcome assessment and adjustment for confounders, were extracted from the included studies. The multivariable association with the highest number of covariates, lowest number of covariates, and unadjusted estimates and corresponding 95% CIs were extracted. DerSimonian and Laird random-effects meta-analyses were performed and yielded conservative confidence intervals around relative risks.

Main outcomes and measures: The principal association measure was day care attendance vs no day care attendance and risk of type 1 diabetes.

Results: Seventeen articles including 22 observational studies of 100 575 participants were included in the meta-analysis. Among the participants, 3693 had type 1 diabetes and 96 882 were controls. An inverse association between day care attendance and risk of type 1 diabetes was found (combined odds ratio, 0.68; 95% CI, 0.58-0.79; P < .001; adjusted for all available confounders). When the 3 cohort studies included were analyzed separately, the risk of type 1 diabetes was 15% lower in the group attending day care; however, the difference was not statistically significant (odds ratio, 0.85; 95% CI, 0.59-1.12; P = .37).

Conclusions and relevance: These results demonstrated that day care attendance appears to be associated with a reduced risk of type 1 diabetes. Increased contacts with microbes in children attending day care compared with children who do not attend day care may explain these findings. However, further prospective cohort studies are needed to confirm the proposed association.