Exposure to neuroactive non-organochlorine insecticides, and diabetes mellitus and related metabolic disturbances: Protocol for a systematic review and meta-analysis

Objectives: To assess whether exposure to specific classes of neuroactive non-organochlorine insecticides is associated with diabetes mellitus or related metabolic traits. Methods: Eligibility criteria: Any type of epidemiological and human exposure studies providing an exposure contrast to neuroactive non-organochlorine insecticides and a measure of association to diabetes mellitus or related metabolic traits. We will include published peer-reviewed studies in both English and non-English language. Information sources: Articles will be located in the NCBI PubMed, Embase, Scopus, Web of Science and LILACS databases, supplemented with manual searching of reference lists and articles citing the included studies. Risk of bias assessment: Risk of bias in individual studies will be assessed using tools from the Navigation Guide systematic review methodology, while the risk of bias at the outcome level will be assessed according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guidelines. Data synthesis and analysis: When studies are sufficiently similar in population, exposure, comparator and effect estimate to meaningfully allow quantitative synthesis, we will perform meta-analysis. Otherwise, results will be summarized qualitatively. Funding: The authors are paid employees of their respective institutions. MRHH is a Ph.D. student working under grants from Aarhus University and the National Research Centre for the Working Environment. Registration: PROSPERO CRD42017068861.