A meta-analysis of passive smoking and risk of developing Type 2 Diabetes Mellitus

To assess passive smoking as a risk factor for developing type 2 Diabetes Mellitus (T2DM).

A search of PubMed, Web of Knowledge, Elsevier ScienceDirect and Springer (up to March, 2014) databases were performed using subject and random words. Two authors independently extracted the data. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of included studies. The odds ratio (ORs) for the association was determined using a fix-effects model. Subgroup and sensitivity analyses were performed and publication bias was assessed.

7 prospective studies were included in this meta-analysis which included a total of 162,001 subjects. The overall OR for developing T2DM for passive smoking was 1.33 (95% confidence interval (CI) 1.20-1.46), with no significant heterogeneity between studies. The result was stable in the subgroup and sensitivity analyses, however there was evidence of publication bias. After the "fill and trim" method, the recalculated OR was 1.27 (95%CI 1.16-1.40).

Passive smoking is a risk factor of T2DM even in those who were not themselves active smokers.