Meta-analytic evaluation for the spatio-temporal patterns of the associations between common risk factors and type 2 diabetes in mainland China

There is a dearth of accurate information about the associations between risk factors and type 2 diabetes in mainland China. We conducted a systematic review and meta-analysis to explore the spatio-temporal patterns of the associations between common risk factors and type 2 diabetes in adults at least 18 years old in mainland China. We searched English and Chinese databases from January 1st, 1997 to December 31st, 2017 for relevant observational studies. Overall and stratification analyses including secular trends and temporal distributions were conducted, odds ratio (OR) and 95% confidence interval (CI) were calculated by applying random-effects model. Thirty-five studies were included. Type 2 diabetes was positively associated with a family history of type 2 diabetes (OR 2.89, 95%CI 2.38–3.49), hypertension (OR 2.73, 95%CI 2.25–3.36), central obesity (OR 2.28, 95%CI 1.94–2.68), dyslipidemia (OR 2.23, 95%CI 1.70–2.91), hypertriglyceridemia (OR 2.18, 95%CI 1.64–2.92), general obesity (OR 1.90, 95%CI 1.66–2.18), hypercholesterolemia (OR 1.65, 95%CI 1.32–2.06), smoking (OR 1.26, 95%CI 1.13–1.40), and drinking (OR 1.20, 95%CI 1.05–1.36), whereas a negative association with female gender (OR 0.87, 95%CI 0.78–0.97) existed. Except for female gender and drinking, the pooled effects of temporal and spatial stratification for the other five risk factors were consistent with the above results. For temporal stratification, the ORs of general obesity increased gradually during the periods of 1992 to 2005, 2006 to 2010, and 2011 to 2017, while the ORs of a family history declined. For regional stratification, the magnitudes of ORs for hypertension, dyslipidemia, and hypercholesterolemia in northern areas were larger than that in southern areas, while opposite situation occurred for a family history. Except for the factor a family history, provincial results for the other nine risk factors differed from the overall results and among provinces. Effect differences existed for modifiable and non-modifiable risk factors in secular trends and regional distribution, which is of potential public health importance for type 2 diabetes prevention.