Age and sex effects on HbA1c. A study in a healthy Chinese population

To evaluate whether glycohemoglobin levels increase with age in both sexes and to determine the effect of BMI on this increment.

A cross-sectional survey of 4,580 healthy Chinese men and women, aged 20-85 years, was performed. All subjects who did not have identifiable diseases and who were not on medication known to influence glucose tolerance were recruited from participants at the preventive services of the National Cheng-Kung University Hospital. As an indicator of plasma glucose levels, glycohemoglobin was measured. The subjects were classified according to their age and BMI for both men and women, and any relationships with glycohemoglobin levels were evaluated.

In all the BMI groups divided into quartiles, glycohemoglobin levels increased with age. The largest elevation of glycohemoglobin was observed in the 45- to 54-year-old age-group, except in men with a BMI between the lowest and highest quartiles. The group with a BMI above the highest quartile had a higher glycohemoglobin than the group with a BMI below the lowest quartile in men aged < 54 years and women aged 35-64 years. Men had higher average glycohemoglobin levels than women < 55 years of age.

The age factor itself may cause an elevation in glycohemoglobin independent of other age-related factors in Chinese men and women, and there is a sex difference with a lower average glycohemoglobin level in women before menopause. Furthermore, BMI, but not a family predisposition to diabetes or leisure-time physical activity, affects this age-dependent increase in glycohemoglobin levels.