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Acta Diabetol (2014) 51:875882 DOI 10.1007/s00592-014-0639-2
ORIGINAL ARTICLE
Screening with HbA1c identies only one in two individuals with diagnosis of prediabetes at oral glucose tolerance test: ndings in a real-world Caucasian population
Nino Cristiano Chilelli Chiara Cosma
Eugenio Ragazzi Silvia Burlina Martina Zaninotto
Mario Plebani Annunziata Lapolla
Received: 6 June 2014 / Accepted: 13 August 2014 / Published online: 6 September 2014 Springer-Verlag Italia 2014
AbstractObjective Discordance between HbA1c and OGTT in screening pre-diabetes may occur because of lack of laboratory standardization, distinct underlying pathophysio-logical processes or different ethnicity. We evaluated HbA1c efcacy for screening OGTT-dened IFG and IGT conditions in a large Caucasian population using the newly revised IFCC protocol.
Research design and methods A total of 501 consecutive subjects were screened for pre-diabetic conditions with OGTT with 75 g of glucose. Testing for HbA1c, lipid prole and fasting insulin levels was also performed. For detecting differences between continuous variables, ANOVA followed by Tukeys honestly signicant difference (HSD) post hoc test was used. Logistic regression and ROC curve analysis were also performed for assessing HbA1c screening efcacy.
Results ROC curve analysis showed that optimal HbA1c cut-off for detecting IFG was 5.6 % (sensitivity of 78 %
and specicity of 63 %), while for IGT, the optimal cut-off was 5.9 % (sensitivity of 46 % and specicity of 84 %), with AUCs\0.8. Screening with HbA1c identied 53.4 %
of the 193 patients with IFG and/or IGT diagnosed at OGTT. As regards surrogate markers of insulin resistance, we observed a trend towards higher values of HOMA-IR and lower QUICKI values in subjects with IFG than in those with IGT. Patients with pre-diabetes at both tests had similar values of HOMA and QUICKI, compared with those with altered OGTT only.
Conclusions IFCC-aligned HbA1c assay proved scarcely effective in detecting IFG and/or IGT in a large Caucasian population, identifying only half of the patients with abnormal OGTT. Moreover, adding HbA1c screening to OGTT may be of little benet in identifying subjects with a worse metabolic prole.
Keywords HbA1c OGTT Prediabetes HOMA
QUICKI Screening
Introduction
Individuals with prediabetes conditions are known to carry a signicant risk of type 2 diabetes mellitus and cardiovascular comorbidities [1]. Although great importance has been attributed to screening and the early diagnosis of prediabetes,...