HbA(1c) as a diagnostic tool for diabetes and pre-diabetes: the Bangladesh experience.

AIMS

To evaluate HbA(1c) as a tool for the diagnosis of diabetes and pre-diabetes (impaired glucose tolerance and/or impaired fasting glucose) and to identify the optimal cut-off values suitable for a Bangladeshi population.

METHODS

In this cross-sectional survey in a rural community, 2293 randomly selected individuals aged ≥ 20 years without prior history of diabetes were included. HbA(1c) and other clinical covariates necessary for the diagnosis of diabetes were recorded. Diabetes and pre-diabetes were defined according to the World Health Organization 1999 criteria. The receiver operating characteristic curve was used to determine the performance of HbA(1c).

RESULTS

The prevalences of diabetes and pre-diabetes were 7.9 and 8.6%, respectively. Based on receiver operating characteristic curve analysis, an HbA(1c) cut-off value of ≥ 42 mmol/mol (≥ 6.0%) gave an optimal sensitivity of 86.2% and specificity of 93.3%, with an area under the curve of 0.949 to predict diabetes using the oral glucose tolerance test as the gold standard; a cut-off value of ≥ 38 mmol/mol (≥ 5.6%) gave an optimal sensitivity of 68.0% and specificity of 66.4%, with an area under the curve of 0.714 to predict pre-diabetes. In subjects at high risk of diabetes, HbA(1c) ≥ 42 mmol/mol (≥ 6.0%) showed higher sensitivity than fasting plasma glucose ≥ 7.0 mmol/l, 2-h plasma glucose ≥ 11.1 mmol/l and HbA(1c) ≥ 48 mmol/mol (≥ 6.5%).

CONCLUSIONS

An HbA(1c) cut-off value of ≥ 42 mmol/mol (≥ 6.0%) was highly sensitive and specific in diagnosing diabetes mellitus. This optimal cut-off level may be suitable as a diagnostic criterion for diabetes in a Bangladeshi population.