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

OBJECTIVES: We 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.

METHODS: A 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 (> or =5.8%). The cumulative incidence of diabetes in 2002, as defined by the 1997 American Diabetes Association (ADA) diagnostic criteria, was compared between groups.

RESULTS: The 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.

CONCLUSIONS: The 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 > or =5.55 mmol/l.