RT Journal Article SR Electronic T1 Vitamin B12 and risk of diabetes: new insight from cross-sectional and longitudinal analyses of the China Stroke Primary Prevention Trial (CSPPT) JF BMJ Open Diabetes Research & Care JO BMJ Open Diab Res Care FD American Diabetes Association SP e001423 DO 10.1136/bmjdrc-2020-001423 VO 8 IS 1 A1 Lishun Liu A1 Xiao Huang A1 Binyan Wang A1 Yun Song A1 Tengfei Lin A1 Ziyi Zhou A1 Zhuo Wang A1 Yaping Wei A1 Huiyuan Guo A1 Ping Chen A1 Yan Yang A1 Wenhua Ling A1 Youbao Li A1 Xianhui Qin A1 Genfu Tang A1 Chengzhang Liu A1 Jianping Li A1 Yan Zhang A1 Pierre A Zalloua A1 Xiaobin Wang A1 Yong Huo A1 Hao Zhang A1 Xiping Xu YR 2020 UL http://drc.bmj.com/content/8/1/e001423.abstract AB Introduction Previous studies in mostly Western populations have yielded conflicting findings on the association of vitamin B12 with diabetes risk, in part due to differences in study design and population characteristics. This study sought to examine the vitamin B12–diabetes association in Chinese adults with hypertension by both cross-sectional and longitudinal analyses.Research design and methods This report included a total of 16 699 participants from the China Stroke Primary Prevention Trial, with pertinent baseline and follow-up data. Diabetes mellitus was defined as either physician-diagnosed diabetes, use of glucose-lowering drugs, or fasting blood glucose (FBG) ≥7.0 mmol/L. New-onset diabetes was defined as any new case of onset diabetes during the follow-up period or FBG ≥7.0 mmol/L at the exit visit.Results At baseline, there were 1872 (11.2%) patients with diabetes; less than 1.5% had clinical vitamin B12 deficiency (<148.0 pmol/L). Over a median follow-up period of 4.5 years, there were 1589 (10.7%) cases of new-onset diabetes. Cross-sectional analyses showed a positive association between baseline vitamin B12 levels and FBG levels (β=0.18, 95% CI 0.15 to 0.21) and diabetes (OR=1.16, 95% CI 1.10 to 1.21). However, longitudinal analyses showed no association between baseline vitamin B12 and new-onset diabetes or changes in FBG levels. Among a subset of the sample (n=4366) with both baseline and exit vitamin B12 measurements, we found a positive association between an increase in vitamin B12 and an increase in FBG.Conclusions In this large Chinese population of patients with hypertension mostly sufficient with vitamin B12, parallel cross-sectional and longitudinal analyses provided new insight into the conflicting findings of previous studies, and these results underscore the need for future studies to consider both baseline vitamin B12 and its longitudinal trajectory in order to better elucidate the role of vitamin B12 in the development of diabetes. Such findings would have important clinical and public health implications.