Stability and reliability of glycated haemoglobin measurements in blood samples stored at -20°C.
OBJECTIVE
To validate the stability of glycated haemoglobin (HbA1c) measurements in blood samples stored at -20°C for up to one month.


METHODS
The study group comprised 142 type 2 diabetic subjects visiting a tertiary centre for diabetes at Chennai city in south India. The HbA1c assay was done on a fasting blood sample using the Bio-Rad Variant machine on Day 0 (day of blood sample collection). Several aliquots were stored at -20°C and the assay was repeated on the 3rd, 7th, 15th, and 30th day after the sample collection. Bland-Altman plots were constructed and variation in the HbA1c levels on the different days was compared with the day 0 level.


RESULTS
The median differences between HbA1c levels measured on Day 0 and the 3rd, 7th, 15th, and 30th day after blood collection were 0.0%, 0.2%, 0.3% and 0.5% respectively. Bland-Altman plot analysis showed that the differences between the day '0' and the different time points tend to get larger with time, but these were not clinically significant.


CONCLUSIONS
HbA1c levels are relatively stable up to 2weeks, if blood samples are stored at -20°C.
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India.
Vijayachandrika
V
Venkataraman
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India.
Ranjit Mohan
RM
Anjana
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India.
Rajendra
R
Pradeepa
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India.
Mohan
M
Deepa
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India.
Ramamoorthy
R
Jayashri
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India.
Viknesh Prabu
VP
Anbalagan
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India.
Bridgitte
B
Akila
University College of Medical Sciences and GTB Hospital, Delhi, India.
Sri Venkata
SV
Madhu
All India Institute of Medical Sciences, New Delhi, India.
Ramakrishnan
R
Lakshmy
Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Noncommunicable Diseases Prevention and Control, Chennai, India. Electronic address: drmohans@diabetes.ind.in.
Viswanathan
V
Mohan
D000368:Aged; D002851:Chromatography, High Pressure Liquid; D003080:Cold Temperature / Q000009:adverse effects; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000188:drug therapy; D004359:Drug Therapy, Combination; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D006943:Hyperglycemia / Q000517:prevention & control; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007194:India; D008297:Male; D008875:Middle Aged; D010949:Plasma; D055550:Protein Stability; D015203:Reproducibility of Results; D062606:Tertiary Care Centers; D013997:Time Factors
D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; C517652:hemoglobin A1c protein, human
Asian Indians; HbA1c; Reliability; Stability; Stored samples