HbA(1c) measurement improves the detection of type 2 diabetes in high-riskindividuals with nondiagnostic of levels at fasting plasma glucose - The Early Diabetes Intervention Program (EDIP)

OBJECTIVE - Whereas new diagnostic criteria based on a fasting plasma gluco se (FPG) of >126 mg/dl (7.8 mmol/l) hale improved the detection of diabetes , multiple reports indicate that many people with diabetes diagnosed by 2-h oral glucose tolerance rest (OGTT) glucose measurements of greater than or equal to 11.1 mmol/l (200 mg/dl) would remain undiagnosed based on this FP G criteria. Thus, improved methods to detect diabetes are particularly need ed for high-risk individuals. We evaluated whether the combination of FPG a nd HbA(1c) measurements enhanced detection of diabetes in those individuals at risk for diabetes with nondiagnostic err minimally elevated FPG, RESEARCH DESIGN AND METHODS - We analyzed FPG, OGTT, and HbA(1c) data from 244 subjects screened for participation in the Early Diabetes intervention Program (EDIP). RESULTS - Of 2+4 high-risk subjects studied by FPG measurements and OGTT, 2 4% of the individuals with FPG levels of 5,5-6.0 mmol/l (100-109 mg/dl) had OGTT-diagnosed diabetes, and nearly 50% of the individuals with FPG levels of 6.1-6.9 mmol/l (110-125 mg/dl) had OGTT-diagnosed diabetes. In the subj ects with OGTT-diagnosed diabetes and FPG levels between 5.5 and 8,0 mmol/l , detection of an elevated HbA(1c) (>6.1% or mean +/- 2 SDs) led to a subst antial improvement in diagnostic sensitivity over the FPG threshold of 7.0 mmol/l (61 vs. 45%, respectively, P = 0.002), Concordant FPG levels greater than or equal to7.0 mmol/l (currently recommended for diagnosis) occurred in only 19% of our cohort with type 2 diabetes. CONCLUSIONS - Diagnostic criteria based on FPG criteria are relatively inse nsitive in the detection of early type 2 diabetes in at-risk subjects. HbA( 1c) measurement improves the sensitivity of screening in high-risk individu als.