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 HbA_1c 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. HbA_1c 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 HbA_1c 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 HbA_1c 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 HbA_1c 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 HbA_1c 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.