HbA1c local reference ranges: Effects of age, sex and ethnicity

Objective: To determine a local HbA1c reference range. Design: Healthy volunteers recruited into an observational study. Subjects: 262 healthy volunteers. Subjects were excluded if known to be diabetic or on medication known to interfere with glucose levels or if random capillary blood glucose was >10mmol/L. Conclusion: Our local reference range for DCA 2000 measurement of HbA1c has now been established and is 5.5% (+/−0.5). Two standard deviations allow the normal range to rise to 6.5%. Significant (if small) differences were seen between sex, age and ethnicity. Districts, particularly those with non‐white populations, should establish local reference ranges for measurement of glycated haemoglobin. This study shows that it is practical to do so. Results: Reference range was mean 5.5% (+/−0.5). There were differences in ethnicity, sex and age. Ethnicity: Mean HbA1c in which (n=135) was 5.3% (+/−0.4), which was lower than for Indo‐Asians (n=127), which was 5.7% (+/−0.5):p=0.001. Sex: In females (n=140) mean HbA1c was 5.4% (+/−0.45), which was lower than for males (n=122) 5.6% (+/−0.5): p=0.006. Age: For white males aged 20‐44 the mean value was 5.1% compared to a mean value of 5.6% in men >65 years. White females changed from 5.0% at ages 20–44 to 5.4% for >65years. Indo‐Asian females changed from 5.3% at ages 20–44 to 5.7% in women >65 years. However, for Indo‐Asian men aged20‐44 the mean value was 5.6% and remained at 5.6% above the age of 65 years.