Diversity in the risk of type 2 diabetes associated with age, sex, and 1-h post-load plasma glucose levels in the Japanese population with prediabetes.

Aims We investigated the risk of type 2 diabetes in the Japanese population with prediabetes, focusing on prediabetes categories, age- and sex-related differences, and plasma glucose levels during a 75-g oral glucose tolerance test. Methods This retrospective cohort study included 11,414 participants (5330, 2560, 1501, and 2023 with normal fasting glucose/normal glucose tolerance, isolated impaired fasting glucose [IFG], isolated impaired glucose tolerance [IGT], and IFG plus IGT, respectively). The risk of type 2 diabetes was stratified by age and sex. Moreover, prediabetes was subdivided according to fasting plasma glucose (FPG) and 1-h post-load glucose levels. Results Over a mean 6.3-year follow-up period, 1002 participants developed type 2 diabetes. The risk of type 2 diabetes was higher in isolated IFG than isolated IGT in elderly participants, but not in middle-aged participants. A higher risk was evident in isolated IFG in women, but not men. Moreover, about a 27- and 29-fold difference exists in men and women, respectively, in the risk of type 2 diabetes among the subdivided prediabetes categories. Conclusion The assessment of age and sex-differences and subdivided prediabetes categories based on FPG and 1-h post-load glucose levels may effectively evaluate the risk of type 2 diabetes, which displays marked diversity.