Effect of Aging on HbA1c in a Working Male Japanese Population

Abstract

OBJECTIVE To evaluate whether there is any change in HbA1c with age and to determine the effects of body mass index (BMI), exercise, and family history of diabetes on this change. RESEARCH DESIGN AND METHODS A cross-sectional survey of 7,664 male Japanese workers aged 20–59 years was performed. All subjects received a physical examination that included measurement of HbA1c as an indicator of plasma glucose level. The subjects were classified according to their ages and BMIs, and any relationship with HbA1c levels was evaluated. Information on physical activity and family history of diabetes was obtained by a questionnaire. RESULTS In all BMI groups, HbA1c increased with age. The greatest increase in HbA1c was observed in the 40- to 49-year-old age-group in subjects with a BMI ≤26 kg/m2 and in the 30- to 39-year-old age-group in subjects with a BMI >26. HbA1c in the subjects aged 20–29 years did not change with BMI. In contrast, HbA1c in subjects aged 30–59 years was significantly higher in those with a BMI >26 when compared with those with BMI ≤20. The age-dependent increase in HbA1c was greater in subjects with a positive rather than negative family history of diabetes. This age-dependent increase was not affected by active participation in sporting activities of mild to moderate intensity for 3 or more days per week. CONCLUSIONS The age-dependent increase in HbA1c may be a consequence of the aging process itself. Furthermore, both BMI and a hereditary predisposition to diabetes, but not active participation in sports, affect this age-dependent increase in HbA1c.