Cross-Sectional and Longitudinal Associations between Serum Bilirubin and Prediabetes in a Health Screening Population.

Objectives: Longitudinal associations between total bilirubin (TB) and prediabetes have not been reported. This study investigated cross-sectional and longitudinal associations between TB and prediabetes.

Methods: Cross-sectional associations between TB and prediabetes were investigated in 3681 nondiabetic subjects. Longitudinal associations between TB and prediabetes over 6 years were investigated in 2149 subjects who were normoglycemic at baseline. Prediabetes was defined as fasting plasma glucose (FPG) levels of ≥5.6 mmol/L or glycated hemoglobin levels of ≥5.7% excluding diabetes.

Results: The prevalence of prediabetes was 25.4%, and the cumulative incidence of prediabetes during 6 years was 25.5% in a Japanese health screening population. Prevalent prediabetes was significantly associated with the quintiles of TB in nonsmoking men (trend, p<0.001) and women (trend, p=0.012), but not in smoking men (trend, p=0.689). Incident prediabetes was not significantly associated with the quintiles of TB, while it was positively associated with 1 standard deviation increase in TB in nonsmoking men (hazard ratio [95% confidence interval]; 1.21 [1.07 to 1.37], p=0.002).

Conclusions: TB levels were significantly inversely associated with prevalent prediabetes in nonsmokers, but not in smokers, whereas an inverse association between TB levels and incident prediabetes seemed to be unlikely.