Use of HbA 1c in Predicting Progression to Diabetes in French Men and Women Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR) CELINE DROUMAGUET, MD, MSC 1 BEVERLEY BALKAU, PHD 1,2 DOMINIQUE SIMON, MD, PHD 1,2,3 EMILE CACES, MSC 4 JEAN TICHET, MD 4 MARIE ALINE CHARLES, MD 1,2 EVELINE ESCHWEGE, MD 1,2 THE DESIR STUDY GROUP* OBJECTIVE — Early identification of subjects at high risk for diabetes is essential, and ran- dom HbA 1c (A1C) may be more practical than fasting plasma glucose (FPG). The predictive value of A1C, in comparison to FPG, is evaluated for 6-year incident diabetes. RESEARCH DESIGN AND METHODS — From the French cohort study Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR), 1,383 men and 1,437 women, aged 30 – 65 years, were volunteers for a routine health check-up. Incident diabetes was defined by FPG 7.0 mmol/l or treatment by antidiabetic drugs. Multivariate logistic regression models were used to predict diabetes at 6 years. Receiver operating characteristic curves com- pared the predictive values of A1C and FPG. RESULTS — At 6 years, 30 women (2.1%) and 60 men (4.3%) had developed diabetes. Diabetes risk increased exponentially with A1C in both sexes (P  0.001). After stratifying on FPG, A1C predicted diabetes only in subjects with impaired fasting glucose (IFG) (FPG 6.10 mmol/l): the odds ratio (95% CI) for a 1% increase in A1C was 7.20 (3.00 –17.00). In these subjects, an A1C of 5.9% gave an optimal sensitivity of 64% and specificity of 77% to predict diabetes. CONCLUSIONS — A1C predicted diabetes, even though the diagnosis of diabetes was based on FPG, but it was less sensitive and specific than FPG. It could be used as a test if fasting blood sampling was not available or in association with FPG. In subjects with IFG, A1C is better than glucose to evaluate diabetes risk, and it could be used to select subjects for intensive early intervention. Diabetes Care 29:1619 –1625, 2006 T he prevalence of type 2 diabetes is increasing worldwide, and it is pro- jected that the number of adults with diabetes will double between 2000 and 2030 (1). This means a large burden for the health care system. Recent clinical trials have demonstrated that lifestyle (2– 4) or pharmaceutical (4 – 6) interven- tions in individuals with impaired glucose tolerance (IGT) can delay or prevent dia- betes; thus high-risk subjects should be identified for early intensive lifestyle counseling or even pharmaceutical treat- ment (7). Fasting and 2-h plasma glucose after an oral glucose tolerance test (OGTT) are currently used to identify subjects at high risk of diabetes (8): those with impaired fasting glucose (IFG) and IGT. However, the OGTT is not common in clinical prac- tice, because it is time consuming, costly, and less reproducible (9) than measure- ment of fasting plasma glucose (FPG). HbA 1c (A1C), an indirect measure of mean blood glucose over the previous 2–3 months, is correlated with FPG and 2-h plasma glucose (10 –12). A1C is more reproducible than FPG (13) and within- subject coefficients of variation are 1.7 and 5.7%, respectively (14). Moreover, measurement of A1C does not require that the subject is fasting. The use of A1C could better integrate chronic hypergly- cemia than FPG. Few studies have investigated pre- dicting diabetes using A1C and none in a Caucasian population. Moreover, previ- ous investigations were in populations at high risk of diabetes. A study in Pima In- dians (15) reported that A1C was an in- dependent predictor for diabetes only in individuals with IGT, not in subjects with normal 2-h plasma glucose. The same re- lation was found in a Chinese study (16). To determine whether A1C predicted incident diabetes after a 6-year follow-up in a Caucasian population, we analyzed data from the prospective French cohort study: Data from an Epidemiological Study on the Insulin Resistance Syn- drome (DESIR). RESEARCH DESIGN AND METHODS — The 3,854 subjects studied, aged 30 – 65 years, were in- cluded in 1994–1996 in the DESIR Study, a follow-up study on the develop- ment of the insulin resistance syndrome. They were volunteers for a routine health check-up in seven Health Examination Centers financed by the French Social Se- curity in the center-west of France. All participants gave informed consent, and the study was approved by an ethics com- mittee (Comite ´ Consultatif de Protection ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● From the 1 Institut National de la Sante ´ et de la Recherche Me ´ dicale U258, Villejuif, France; the 2 Faculte ´ de Me ´decine, University of Paris-Sud, Villejuif, France; the 3 Service de Diabe ´tologie et Me ´tabolisme, Groupe Hospitalier Pitie ´-Salpe ˆtrie ` re, Paris, France; and the 4 Institut inter-Re ´ gional pour la Sante ´ , La Riche, France. Address correspondence and reprint requests to Beverley Balkau, INSERM U258-IFR69, 16 avenue Paul Vaillant-Couturier, 94807 Villejuif cedex, France. E-mail: balkau@vjf.inserm.fr. Received for publication 23 December 2005 and accepted in revised form 13 April 2006 *A complete list of DESIR Study Group members can be found in the APPENDIX. Abbreviations: DESIR, Data from an Epidemiological Study on the Insulin Resistance Syndrome; FPG, fasting plasma glucose; IFG, impaired fasting glucose; IGT, impaired glucose tolerance; OGTT, oral glucose tolerance test; ROC, receiver operating characteristic. A table elsewhere in this issue shows conventional and Syste `me International (SI) units and conversion factors for many substances. DOI: 10.2337/dc05-2525 © 2006 by the American Diabetes Association. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Cardiovascular and Metabolic Risk O R I G I N A L A R T I C L E DIABETES CARE, VOLUME 29, NUMBER 7, JULY 2006 1619 Downloaded from http://diabetesjournals.org/care/article-pdf/29/7/1619/656452/zdc00706001619.pdf by guest on 05 June 2022