Fig. 1

Timeline of the study design. Subjects without diabetes and cardiovascular disease at first visit (1999–2002) or (2002–2005) were followed 3 years later for the following changes: (1) Normal fasting glucose (NFG) to NFG or impaired fasting glucose (IFG), (2) Normal glucose tolerance (NGT) to NGT or impaired glucose tolerance (IGT), (3) NFG and NGT (NFG/NGT) to NFG/NGT or IFG/IGT, (4) IFG to NFG, IFG or diabetes, (5) IGT to NGT, IGT or diabetes and 6) IFG and/or IGT (IFG/IGT) to NFG/NGT, IFG/IGT or diabetes. Regarding the limited number of those with normoglycemia at baseline who directly converted to diabetes [NFG to diabetes (n = 60), NGT to diabetes (n = 52), NFG/NGT to diabetes (n = 24)], these groups were excluded