Prediabetes screening using HbA1c may identify fewer cases than impaired fasting glucose criteria
August - 17 - 2011
Prediabetes is defined as a state of elevated glucose levels that still fall below the cut-off criterion for diabetes diagnosis. The progression from prediabetes to full-blown type 2 diabetes is not well-understood. A longitudinal population-based study investigated the prevalence of prediabetes and its progression to type 2 diabetes in a Japanese cohort. Prediabetes prevalence was estimated using two types of diagnostic criteria, the original criterion based on fasting plasma glucose (FPG) levels of 5.6-6.9 mmol/L and the new criterion based on glycated hemoglobin A1c (HbA1c) levels of 5.7–6.4%. The cohort consisted of 6,241 men and women who were diabetes-free at baseline, followed up for an average of 4.7 years and assessed annually for type 2 diabetes (FPG = 7.0 mmol/L or higher; HbA1c = 6.5% or higher). A total of 2,092 subjects were diagnosed with prediabetes. Among these, HbA1c alone identified 19.7%, impaired fasting glucose (IFG) alone identified 60.7%, and both tests combined identified 19.6%. The new HbA1c-based prediabetes criterion missed many cases identified by IFG screening. The likelihood of progression to type 2 diabetes did not differ between the two screening criteria. Combining both criteria could efficiently identify prediabetic individuals at high risk for diabetes progression and who may require early intervention (Heianza, Y. et al. Lancet 2011, 378(9786): 147).