Utility of 75-g oral glucose tolerance test results and hemoglobin a1c values for predicting the incidence of diabetes mellitus among middle-aged Japanese men -a large-scale retrospective cohort study performed at a single hospital.

Objective: The aim of this study was to investigate the associations between the incidence of diabetes and the accumulation of markers of impaired glucose metabolism; i.e., pre-diabetes.

Methods: This retrospective cohort study recruited 1,631 men without diabetes at baseline who attended more than two routine health check-ups at our institution between 2006 and 2012. The participants were divided into four groups based on the number of markers of impaired glucose metabolism exhibited at the initial examination. The following markers of impaired glucose metabolism were defined as risk factors for diabetes: a fasting plasma glucose level of ≥110 mg/dL, 2-hour plasma glucose level of ≥140 mg/dL and glycated hemoglobin (HbA1c) value of ≥6.0% (42 mmol/moL). The risk of developing diabetes was assessed using a multivariate analysis.

Results: The median examination interval was 1,092 days. The incidence of diabetes rose in association with the number of markers. The subjects with two markers displayed a multivariate-adjusted odds ratio (OR) for diabetes of 19.43 [95% confidence interval (CI): 9.70-38.97] and the subjects with three markers displayed an OR of 48.30 (95% CI: 20.39-115.85) compared with the subjects with one or no markers.

Conclusion: The present results demonstrate the impact of accumulating markers of impaired glucose metabolism on the risk of developing diabetes. Anti-diabetes intervention strategies should aim to comprehensively assess an individual's risk of developing diabetes at the pre-diabetes stage.