Caffeinated and Decaffeinated Coffee Consumption and Risk of Type 2 Diabetes: A Systematic Review and a Dose-Response Meta-analysis
RESEARCH DESIGN AND METHODS
Search Strategy and Selection Criteria
We searched the PubMed and Embase databases for prospective cohort studies or nested case-control studies that evaluated the association between coffee consumption and risk of type 2 diabetes between January 1966 and February 2013. The computer-based searches included the key words coffee and diabetes. No Medical Subject Headings terms were used because of the clear definitions of coffee and diabetes. Reference lists of retrieved articles were manually scanned for all relevant additional studies and review articles. We restricted the search to studies on humans and written in English.
Studies included in this meta-analysis met the following criteria: 1) the study design was prospective cohort or nested case-control; 2) the articles were published in English; 3) the exposure was categorized coffee consumption, including total coffee, caffeinated coffee, or decaffeinated coffee; and 4) the outcome was risk of type 2 diabetes. Studies were excluded if they were cross-sectional in design and if information on dose-response modeling was inadequate, including the number of participants and cases, relative risk (RR) and SE for the estimate, and dose of coffee consumption in each exposure category.
Data Extraction and Quality Assessment
One author (M.D.) assessed study eligibility and extracted the data, and another (M.C.) independently double-checked the available data. The following data were extracted from each study: first author’s name, year of publication, geographical location, follow-up time, sex, a Continue reading