Alterations in HbA(1c) with advancing age in subjects with normal glucose tolerance: Chandigarh Urban Diabetes Study (CUDS).
OBJECTIVE
To study the alterations in HbA(1c) with advancing age in subjects with normal glucose tolerance.


METHODS
Community-based cross-sectional study involving 2368 subjects aged ≥ 20 years from Chandigarh, India. All the subjects underwent an oral glucose tolerance test with 75 g anhydrous glucose and were classified as having normal glucose tolerance, pre-diabetes or diabetes according to World Health Organization 1999 criteria. HbA(1c) was measured on a National Glycohemoglobin Standardization Program-certified Bio-Rad D-10 system and the data were available for 1972 subjects.


RESULTS
Out of 1972 subjects, 1317 (67%) subjects had normal glucose tolerance. There was a significant positive correlation between mean HbA(1c) and age in these subjects (r = 0.308, P(trend) < 0.001). The increase in HbA(1c) with each advancing year was 0.01% above the age of 20 years and corrected HbA(1c) (%) for age was 5.09 + 0.01 (age). The 95th percentile of HbA(1c) exceeded 6.5% (48 mmol/mol) (the American Diabetes Association cut-off for diagnosis of diabetes) in subjects aged ≥ 70 years. A significantly higher number (6.5%, 21/325) of subjects had HbA(1c) of ≥ 6.5% (48 mmol/mol) in those above the age of 50 years compared with those below the age of 50 years (1.7%, 17/992) in the group with normal glucose tolerance (P < 0.001). On multivariate regression analysis, after adjusting for BMI, fasting plasma glucose and 2-h plasma glucose post-glucose load, the correlation of HbA(1c) with age still remained significant (r = 0.241, P < 0.01).


CONCLUSIONS
HbA(1c) increases with advancing age independent of glycaemia, suggesting caution when seeking to achieve the recommended HbA(1c) targets in the elderly population.
Department of Endocrinology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
P
P
Ravikumar
A
A
Bhansali
R
R
Walia
G
G
Shanmugasundar
M
M
Ravikiran
D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D044466:Asian People; D001786:Blood Glucose; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D055815:Young Adult
D001786:Blood Glucose; D006442:Glycated Hemoglobin