Cumulative exposure to impaired fasting glucose and future risk of type 2 diabetes mellitus

Aims: The status of metabolic abnormalities including impaired fasting glucose (IFG) can change over time, yet little is known about how exposure duration to IFG is related to diabetes risk. Methods: Using nationally representative data from the Korean National Health Insurance system, 2,513,127 people who were free of diabetes and who received four consecutive annual health examinations commencing in 2006 or 2007 were followed up at the end of 2016. IFG was defined as fasting blood glucose levels of 100–125 mg/dL. Participants were classified numerically according to the cumulative number of IFG diagnoses. Results: Over 4 years, 53% of the population participants remained normoglycemic, while 3% had persistent IFG and 44% had intermittent IFG. The risk of type 2 diabetes mellitus (DM) increased gradually with increasing IFG exposure score. Subjects with an IFG exposure score of 2, 3, or 4 had a 3.75- to 9.77-fold increased hazard ratio (HR) for incident diabetes (IFG exposure score 0 reference; score 2, HR 3.75, 95% confidence interval [CI] 3.67–3.83; score 3, HR 6.21, 95% CI 6.08–6.36; score 4, HR 9.77, 95% CI 9.53–10.02). Conclusions: Cumulative IFG exposure was associated with a higher risk of type 2 DM in a dose–response fashion.