Accuracy of glycated haemoglobin in screening for pre-diabetes in Asian Indians-a community survey: the Chandigarh Urban Diabetes Study (CUDS)

Aim To compare American Diabetes Association and International Expert Committee recommended cut‐off values of HbA1c for detecting the presence of pre‐diabetes against plasma glucose values obtained from oral glucose tolerance tests in Asian Indians. Methods A cross‐sectional randomly sampled population survey involving 2368 adults, aged ≥ 20 years. HbA1c was measured on a Bio‐Rad 10 system in 1972 subjects. Results Of the 1972 subjects studied, 329 were detected to have pre‐diabetes based on isolated impaired fasting glucose in 125 subjects (6.3%), isolated impaired glucose tolerance in 141 subjects (7.1%) and the presence of both in 63 subjects (3.2%). The HbA1c cut‐off of 34 mmol/mol (5.7%), as recommended by the American Diabetes Association for detecting the presence of pre‐diabetes, showed sensitivity of 62%, specificity 77%, with a positive predictive value of 34.7%, a negative predictive value of 89.5% and accuracy of 67.8%; whereas the HbA1c cut‐off recommended by the International Expert Committee of 42 mmol/mol (6%) had a sensitivity of 36%, specificity of 90%, positive predictive value of 42.7%, negative predictive of 85.4% and an accuracy of 77%. However, both these HbA1c cut‐offs underdiagnosed the presence of pre‐diabetes in 38 and 64% of these subjects, respectively. Conclusions The American Diabetes Association and the International Expert Committee recommended HbA1c cut‐off values and oral glucose tolerance tests identify different pre‐diabetes cohorts. Long‐term prospective studies are required to define the usefulness of one over the other.