Abstract
Objective: Because the American Diabetes Association has recently included HbA1c as the primary diagnostic test for the detection of diabetes mellitus (HbA1c ≥6.5%) we investigated its use as screening parameter for diabetes in a cohort at increased risk for the disease.
Research Design and Methods: During the last 10 years 2 036 Caucasians at risk to develop type 2 diabetes but not having this diagnosis yet, consecutively underwent a 75 g oral glucose tolerance test (OGTT). HbA1c was determined with the HPLC method (Tosoh A1c 2.2), external and internal quality controls were well within the allowed ranges.
Results: The oral glucose tolerance test classified 1 523 individuals as normal glucose tolerant (NGT), 387 as impaired glucose tolerant (IGT) or having impaired fasting glycemia (IFG) and 126 as diabetic. The 6.5% cut-off value of HbA1c classified 47% of the diabetic individuals correctly. Of the remaining 53% diabetic individuals (HbA1c <6.5%) 35% had increased fasting glucose levels, while 65% were only diagnosed by their increased 2 h glucose values.
Conclusion: A cut-off value of 6.5% HbA1c classifies diabetic subjects with a specificity of 98.7%. However, the sensitivity of 46.8% is low, indicating that more than half of diabetic subjects are missed when using this test. The present data shows that the use of HbA1c as a the primary diagnostic test will reduce diabetes prevalence. Furthermore, it suggests, that HbA1c and OGTT measurements cannot simply be exchanged, but most probably detect and define different categories of diabetes, i. e., categories with different risk of cardiovascular disease.
Key words
HbA1c - diagnostic criteria - OGTT
References
-
1
American Diabetes Association.
.
Diagnosis and classification of diabetes mellitus.
Diabetes Care.
2010;
33
(S 01)
62-69
-
2
The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus.
.
Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus.
Diabetes Care.
1997;
20
1183-1197
-
3
Stefan N, Hennige AM, Staiger H. et al .
Alpha2-Heremans-Schmid glycoprotein/fetuin-A is associated with insulin resistance and fat accumulation in the liver in humans.
Diabetes Care.
2006;
29
853-857
-
4
International Expert Committee.
.
report on the role of the A1c assay in the diagnosis of diabetes.
Diabetes Care.
2009;
32
1327-1334
-
5
Consensus Committee.
.
Consensus statement on the worldwide standardization of the haemoglobin A1c measurement: the American Diabetes Association, European Association for the Study of Diabetes, International Federation of Clinical Chemistry and Laboratory Medicine, and the International Diabetes Federation Diabetes.
Care.
2007;
30
2399-2400
-
6
Selvin E, Steffes MW, Zhu H. et al .
Glycated hemoglobin, diabetes, and cardiovascular risk in nondiabetic adults.
N Engl J Med.
2010;
362
800-811
-
7
van ‘t Riet E, Alssema M, Rijkelijkhuizen JM. et al .
Relationship between A1c and Glucose Levels in the General Dutch Population: The New Hoorn Study.
Diabetes Care.
2010;
33
61-66
-
8
Cohen RM, Franco RS, Khera PK. et al .
Red cell life span heterogeneity in hematologically normal people is sufficient to alter HbA1c.
Blood.
2008;
112
4284-4291
-
9
Snieder H, Sawtell PA, Ross L. et al .
HbA1c levels are genetically determined even in type 1 diabetes. Evidence from healthy and diabetic twins.
Diabetes.
2001;
50
2858-2863
-
10
Snieder H, Florez JC.
A genome-wide association study of treated A1C: a genetic needle in an environmental haystack?.
Diabetes.
2010;
59
332-334
-
11
Little RR, Sacks DB.
HbA1c: how do we measure it and what does it mean?.
Curr Opin Endocrinol Diabetes Obes.
2009;
16
113-118
-
12
Rohlfing CL, Wiedmeyer HM, Little RR. et al .
Defining the relationship between plasma glucose and HbA1c: analysis of glucose profiles and HbA1c in the Diabetes Control and Complications Trial.
Diabetes Care.
2002;
25
275-278
-
13
Young IS.
The Reporting of Estimated Glucose with Hemoglobin A1c.
Clin Chem.
2010 Apr;;
54 (4)
547-549
-
14
Herman WH, Ma Y, Uwaifo G. et al .
Diabetes Prevention Program Research Group. Differences in A1c by race and ethnicity among patients with impaired glucose tolerance in the Diabetes Prevention Program.
Diabetes Care.
2007 Oct;
30
(10)
2453-2457
-
15
Singleton JR, Smith AG, Russell JW. et al .
Microvascular complications of impaired glucose tolerance.
Diabetes.
2003;
52
2867-2873
-
16
Glucose tolerance and mortality: comparison of WHO and American Diabetes Association diagnostic criteria.
.
The DECODE study group. European Diabetes Epidemiology Group. Diabetes Epidemiology: Collaborative analysis Of Diagnostic criteria in Europe.
Lancet.
1999 Aug 21;
354
(9179)
617-621
-
17
Tominaga M, Eguchi H, Manaka H. et al .
Impaired glucose tolerance is a risk factor for cardiovascular disease, but not impaired fasting glucose. The Funagata Diabetes Study.
Diabetes Care.
1999 Jun;
22
(6)
920-924
-
18
Eddy D, Schlessinger L, Kahn R. et al .
Relationship of insulin resistance and related metabolic variables to coronary artery disease: a mathematical analysis.
Diabetes Care.
2009;
Feb
32: 361-366
-
19
Cederberg H, Saukkonen T, Laakso M. et al .
Postchallenge Glucose, HbA1c, and Fasting Glucose as Predictors of Type 2 Diabetes and Cardiovascular Disease: A 10-year Prospective Cohort Study.
Diabetes Care.
2010 Sep;
33 (9)
2077-2083
-
20
Li-nong J, Wei L, Wei L. et al .
Impact of newly recommended HbA1c-based diabetes diagnostic criteria on the prevalence of diabetes and high risk individual in clinical and community population in China.
Chin Med J (Engl).
2010 Apr 20;
123
(8)
1103-1104
Correspondence
A. PeterMD
Central Laboratory
Department of Internal
Medicine
Division of Endocrinology,
Diabetology,
Pathobiochemistry and Clinical
Chemistry
University Hospital of Tübingen
Tübingen
Germany
Phone: +49/7071/298 5673
Fax: +49/7071/294 582
Email: Andreas.Peter@med.uni-tuebingen.de
