Effects of age and obesity on glycated haemoglobin and 1,5-anhydroglucitol in screening for type 2 diabetes mellitus.

Abstract

The diagnostic accuracy of glycated haemoglobin (HbA1c) and 1,5-anhydroglucitol (AG) and their association with age and obesity in the community screening for Type 2 diabetes were investigated. HbA1c and AG were measured in 368 subjects at the time of an oral glucose tolerance test (OGTT) based on WHO criteria. The impact of age and obesity on the probability of diabetes was evaluated by multivariate logistic regression analysis. Receiver operating characteristic (ROC) analysis was used to assess diagnostic accuracy of each method. The areas under ROC curves were compared for subjects aged 30-59 and 60-82 years. In the logistic analysis, age was associated with the probability of diabetes, while body mass index did not contribute to the model. The paired ROC analyses indicated that HbA1c was superior to AG only in the younger subjects. When the areas for two age groups were compared, both HbA1c and AG performed better in the younger than older subjects. We conclude that for the younger subjects, HbA1c value is highly sensitive (100.0%) and specific (90.4%) and is helpful for the diagnosis of Type 2 diabetes. On the other hand for the older subjects, both HbA1c and AG are poor screening tests in reference to the OGTT standard.