Risk Factors of Type2 Diabetes Mellitus: A Systematic Review of Systematic Reviews and Meta-Analyses of Prospective Cohort Studies

Abstract The prevalence of type 2 diabetes mellitus (T2DM) is rapidly increasing across the world and so is the related academic research. This study undertook a systematic review of extant systematic reviews and meta-analyses of prospective cohort studies, to identify, summarise, and synthesise the available evidence on the factors associated with the risk of T2DM incidence. A systematic literature search across three databases and Google Scholar, as well as hand-searching of reference lists and citations of eligible papers were conducted for systematic reviews that included a meta-analysis of prospective cohort studies. Methodological quality of eligible reviews was assessed with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations and a Measurement Tool to Assess Systematic Reviews (AMSTAR) technique. Forty eligible systematic reviews and meta-analyses of prospective cohort studies examining factors that may be associated with the risk of T2DM were published between 2007 and 2020. Results suggest that adherence to healthy dietary patterns, coffee intake, tea consumption more than 3–4 cups per day, normal quality and quantity of sleep, regular physical activity, low to moderate alcohol consumption (specially wine) were associated with reduced risk of T2DM, while low socio- economic position, smoking, poor quality and quantity of sleep, unhealthy lifestyles, exposure to some air pollutants and noise traffic were associated with increased risk of T2DM. Further prospective studies with well design and sufficient follow-up period (> 10 years) are needed to confirm the available evidence.