A pan-India study has found that high HbA1c (glycated haemoglobin) levels may be normal in older people.

The aim of the study, led by V. Mohan and his team of doctors from Madras Diabetes Research Foundation (MDRF) and Dr. Mohan’s Diabetes Specialities Centre, was to check if HbA1C — a test of three months control of diabetes — increased with age even among individuals with normal glucose tolerance (NGT). They obtained data on glycaemic parameters of different age groups — in adults aged 20 and above — from the Indian Council of Medical Research – India Diabetes study (ICMR-INDIAB).

The researchers assessed the age-wise distribution of HbA1c among individuals with NGT confirmed by an oral glucose tolerance test using the World Health Organisation criteria. The results were validated in another epidemiological study — CURES study — conducted in Chennai, according to a press release. The report was published in Acta Diabetologica, a journal that publishes reports of experimental and clinical research on diabetes mellitus and related metabolic disease.

Dr. Mohan, chairman and consultant diabetologist, Dr. Mohan’s Diabetes Research Centre and founder of MDRF, said advancing age was associated with increased prevalence of many chronic diseases, including type 2 diabetes. “However, one needs to be careful while diagnosing type 2 diabetes in the elderly as many of them may have physiological changes in their ability to regulate blood glucose, implying that marginally elevated HbA1C levels need not always be indicative of pathology as it could be a normal age-related change in this population,” he said.

The researchers said that HbA1c levels increased steadily with age, he said. “This suggests that age-specific cut-offs should be used while utilising HbA1c to diagnose diabetes and pre-diabetes to minimise the risk of overdiagnosis and unnecessary initiation of treatment in elderly people,” he said.

In INDIAB study, there was a 0.08% increase in HbA1c for every decadal increase in age. This increase was more significant in women — 0.10% in women versus 0.06% in men, and in the urban population.

R.M. Anjana, vice-president of MDRF, said the conclusion from this study was that a HbA1c of 6.5% that would be considered as diabetes could be normal value in some older people. Laboratory should report age-adjusted normal values for all their lab tests.