Haemoglobin A1c and serum glucose levels and risk of gastric cancer: a systematic review and meta-analysis

BACKGROUND: This systematic review and meta-analysis examined associations between serum levels of haemoglobin A1c (HbA1c) and glucose and the risk of gastric cancer. METHODS: MEDLINE, Embase, and Cochrane Library were searched for studies examining associations between serum levels of HbA1c or glucose and the risk of gastric cancer. Inclusion of studies, quality assessment, and data extraction were conducted independently by two authors. Pooled hazard ratios (HR) with 95% confidence intervals (CI) were synthesised using random-effects models. Cochran’s Q test and I(2) statistic were used to assess heterogeneity. RESULTS: Among 3473 identified studies, 12 were included. Of these, 5 studies examined HbA1c levels and 7 studies examined serum glucose levels. Serum HbA1c levels >6% were associated with an increased risk of gastric cancer (HR 1.36, 95% CI 1.06–1.74). When compared with the lowest glucose categories, the highest glucose categories were associated with a borderline increased risk of gastric cancer (HR 1.11, 95% CI 0.98–1.26). In subgroup analyses, studies that adjusted for Helicobacter pylori infection indicated stronger associations between elevated HbA1c levels and gastric cancer (HR 2.08, 95% CI 1.46–2.98) than those without such adjustment (HR 1.10, 95% CI 0.91–1.32). CONCLUSIONS: Long-standing poor glycaemic control may increase the risk of gastric cancer. REGISTRATION NUMBER: PROSPERO CRD42020157453.