Screening with HbA1c identifies only one in two individuals with diagnosis of prediabetes at oral glucose tolerance test: findings in a real-world Caucasian population
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Discordance between HbA1c and OGTT in screening pre-diabetes may occur because of lack of laboratory standardization, distinct underlying pathophysiological processes or different ethnicity. We evaluated HbA1c efficacy for screening OGTT-defined 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 profile and fasting insulin levels was also performed. For detecting differences between continuous variables, ANOVA followed by Tukey’s honestly significant difference (HSD) post hoc test was used. Logistic regression and ROC curve analysis were also performed for assessing HbA1c screening efficacy.
ROC curve analysis showed that optimal HbA1c cut-off for detecting IFG was 5.6 % (sensitivity of 78 % and specificity of 63 %), while for IGT, the optimal cut-off was 5.9 % (sensitivity of 46 % and specificity of 84 %), with AUCs < 0.8. Screening with HbA1c identified 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.
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 benefit in identifying subjects with a worse metabolic profile.
KeywordsHbA1c OGTT Prediabetes HOMA QUICKI Screening
Conflict of interest
Nino Cristiano Chilelli, Chiara Cosma, Eugenio Ragazzi, Silvia Burlina, Martina Zaninotto, Mario Plebani and Annunziata Lapolla declare that they have no conflict of interest.
Ethics approval was obtained from the institutional review board of the local Ethical Committee.
Human and animal rights disclosure
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008.
Informed consent disclosure
Informed consent was obtained from all patients for being included in the study.
- 10.Vlaar EM, Admiraal WM, Busschers WB et al (2013) Screening South Asians for type 2 diabetes and prediabetes: (1) comparing oral glucose tolerance and haemoglobin A1c test results and (2) comparing the two sets of metabolic profiles of individuals diagnosed with these two tests. BMC Endocr Disord 13(1):8PubMedCrossRefPubMedCentralGoogle Scholar
- 11.Bianchi C, Miccoli R, Bonadonna RC et al; GENFIEV Investigators (2012) Pathogenetic mechanisms and cardiovascular risk: differences between HbA(1c) and oral glucose tolerance test for the diagnosis of glucose tolerance. Diabetes Care 35(12):2607–2612Google Scholar
- 20.Lorenzo C, Wagenknecht LE, Hanley AJ, Rewers MJ, Karter AJ, Haffner SM (2010) A1C between 5.7 and 6.4% as a marker for identifying pre-diabetes, insulin sensitivity and secretion, and cardiovascular risk factors: the Insulin Resistance Atherosclerosis Study (IRAS). Diabetes Care 33:2104–2109PubMedCrossRefPubMedCentralGoogle Scholar
- 26.Otten J, Ahrén B, Olsson T (2014) Surrogate measures of insulin sensitivity vs the hyperinsulinaemic–euglycaemic clamp: a meta-analysis. Diabetologia 57(9):1781–1788 Google Scholar
- 27.Lorenzo C, Wagenknecht LE, Hanley AJ, Rewers MJ, Karter AJ, Haffner SM (2010) A1C between 5.7 and 6.4% as a marker for identifying pre-diabetes, insulin sensitivity and secretion, and cardiovascular risk factors: the Insulin Resistance Atherosclerosis Study (IRAS). Diabetes Care 33(9):2104–2109PubMedCrossRefPubMedCentralGoogle Scholar
- 32.Glad Working Group A1c Delegates WG, Mosca A, Branca MT, Carta M et al (2010) Recommendations for the implementation of international standardization of glycated hemoglobin in Italy. Clin Chem Lab Med 48(5):623–626Google Scholar