The combination of fasting plasma glucose and glycosylated hemoglobin predicts type 2 diabetes in Japanese workers

ObjectivesWe examined the usefulness of the combined use of fasting plasma glucose (FPG) and hemoglobin Alc (HbA1c) levels to predict the progression of diabetes in a Japanese population.MethodsA retrospective cohort study was conducted from 1995 to 2002 among 449 non-diabetic Japanese workers, ages 23–65, in whom baseline FPG levels and HbA1c were measured. Subjects were classified into six groups according to their baseline FPG level: low normal fasting glucose (NFG) (<5.55 mmol/l); high NFG (5.55–6.09 mmol/l); or impaired fasting glucose (IFG) (6.10–6.99 mmol/l), in combination with baseline HbA1c level: low HbA1c (<5.8%) and high HbA1c (≥5.8%). The cumulative incidence of diabetes in 2002, as defined by the 1997 American Diabetes Association (ADA) diagnostic criteria, was compared between groups.ResultsThe overall cumulative incidence of diabetes was 3.8% (17/449). The cumulative incidence of diabetes was 0.6% (2/339) in those with low NFG/normal HbA1c; 0% (0/24) with low NFG/high HbA1c; 6.4% (3/47) with high NFG/normal HbA1c; 23.1% (3/13) with high NFG/high HbA1c; 17.6% (3/17) with IFG/normal HbA1c; and 66.7% (9/17) with IFG/high HbA1c. The odds ratios for diabetes, adjusted for age, sex, body mass index (BMI) and family history of diabetes, were 5.3 (95% CI, 3.0–9.3) and 3.0 (1.7–5.3), per 0.56 mmol/l increase in FPG and 0.5% increase in HbA1c, respectively.ConclusionsThe combined use of FPG and HbA1c levels predicts the progression to diabetes in individuals with no apparent risk. In particular, the combination is recommended for individuals with a FPG ≥5.55 mmol/l.