EFFECT OF AGING ON HBA(1C) IN A WORKING MALE JAPANESE POPULATION

OBJECTIVE - To evaluate whether there is any change in HbA(1c) 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 HbA(1c) as an indicator of plasma glucose level. The subjects were classified according to their ages and BMIs, and any relationship with HbA(1c) levels was evaluated. Information on physical activity and family history of diabetes was obtained by a questionnaire. RESULTS - In all BMI groups, HbA(1c) increased with age. The greatest increase in HbA(1c) was observed in the 40- to 49-year-old age-group in subjects with a BMI less than or equal to 26 kg/m(2) and in the 30- to 39-year-old age-group in subjects with a BMI >26. HbA(1c) in the subjects aged 20-29 years did not change with BMI. In contrast, HbA(1c) in subjects aged 30-59 years was significantly higher in those with a BMI >26 when compared with those with BMI less than or equal to 20. The age-dependent increase in HbA(1c) 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 HbA(1c) 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 HbA(1c).