Utility of HbA1c and fasting plasma glucose for screening of Type 2 diabetes: a meta-analysis of full ROC curves
There is still debate on the optimal threshold for population-based screening of diabetes (diagnosed by the oral glucose tolerance test) using tests like HbA1c or fasting plasma glucose. Meta-analyses provide meaningful input in such situations. The aim of this article is to perform a meta-analysis that includes the complete information reported in the individual studies of two existing systematic reviews.Methods
We screened the individual studies from two systematic reviews and reconstructed the full four-fold tables for every reported threshold. Using a recently proposed meta-analysis model for the comparison of two diagnostic tests, we compared HbA1c with fasting plasma glucose, and estimated meta-analytic receiver operating characteristic curves for both tests using the 11.1 mmol/l threshold of the 2-h post-challenge glucose level (2 h-PG) as the gold standard.Results
We included nine studies from two existing systematic reviews in our analysis.Results
Based on our data set, the optimal threshold lies between 42 and 44 mmol/mol (6.0–6.2%) for HbA1c, and 6.2–6.4 mmol/l for fasting plasma glucose choosing the Youden index as the technical criterion. In addition, we found that there is no relevant difference in the performance of HbA1c and fasting plasma glucose.Conclusions
In our meta-analysis, we found that the optimal threshold with reference to the 2 h-PG should be chosen between 42 and 44 mmol/mol (6.0–6.2%) for HbA1c, and 6.2–6.4 mmol/l for fasting plasma glucose on the basis of maximal sensitivity and specificity.