Characteristics of undiagnosed diabetes mellitus in a population undergoing health screening in Japan: Target populations for efficient screening

AimsTo estimate the prevalence of undiagnosed diabetes mellitus and its relationship with various risk factors in a population undergoing health screening in Japan.MethodsOral glucose tolerance tests were carried out in a total sample of 14,674 Japanese subjects undergoing health screening, aged 20–83 years and without known diabetes. The prevalence of glucose tolerance categories (1999 WHO criteria) was adjusted for sample probabilities. The optimal FPG cut-off point for screening diabetes was estimated using ROC curve analysis for the continuous value of FPG corresponding to a 2-h PG of 200 mg/dl. The number needed to screen (NNTS) to identify one person with undiagnosed diabetes with various risk factors was estimated using the following equation: the number of undiagnosed diabetic plus nondiabetic subjects/the number of undiagnosed diabetic subjects.ResultsThe prevalence of undiagnosed diabetes among men and women was 6.4% (NNTS 15.7) and 3.2% (NNTS 31.7), respectively. The optimal FPG cut-off point for screening diabetes among men and women was 105 and 106 mg/dl, respectively. NNTS was lower in individuals with more risk factors, e.g. aging (≥50), BMI (≥25), hypertension (SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg) and dyslipidemia (TC ≥ 220 and/or HDL-C < 40 and/or TG ≥ 150 mg/dl), resulting in the lowest NNTS in individuals having all four risk factors among men (6.1) and women (6.7), respectively.ConclusionsIn Japan, screening for diabetes may be more efficient among individuals having an FPG of more than 105–106 mg/dl and with more risk factors, especially in men.