Abstract
AIM/INTRODUCTION: As the association between a fasting glucose concentration of 90-99 mg/dL and the onset of type 2 diabetes is still controversial, we aimed to assess it in 37,148 Japanese individuals with a normal plasma glucose concentration. MATERIALS AND METHODS: This long-term retrospective cohort study included individuals having a medical checkup at Panasonic Corporation from 2008 to 2018. In total, 1,028 participants developed type 2 diabetes. RESULTS: Cox regression analyses revealed that the risk for the onset of diabetes increased by 9.0% per 1 mg/dL increase in fasting plasma glucose concentration in subjects with the concentration ranging from 90 to 99 mg/dL. Compared with individuals with a fasting glucose concentration of ≤89 mg/dL, the adjusted hazard ratios for developing diabetes were 1.53 (95% CI; 1.22-1.91), 1.76 (95% CI; 1.41-2.18), 1.89 (95% CI; 1.52-2.35), 3.17 (95% CI; 2.61-3.84), and 3.41 (95% CI; 2.79-4.15) at fasting plasma glucose concentrations of 90-91, 92-93, 94-95, 96-97, and 98-99 mg/dL, respectively. In populations with obesity, the adjusted hazards ratios for developing diabetes were 1.56 (95% CI; 1.15-2.09), 1.82 (95% CI; 1.37-2.40), 2.05 (95% CI; 1.55-2.69), 3.53 (95% CI; 2.79-4.46), and 3.28 (95% CI; 2.53-4.22) at fasting plasma glucose concentrations of 90-91, 92-93, 94-95, 96-97, and 98-99 mg/dL, respectively. CONCLUSIONS: This study demonstrates that the risk of type 2 diabetes among subjects having a fasting plasma glucose concentration of 90-99 mg/dL, is progressively higher with an increasing level of fasting plasma glucose concentration in a Japanese people.