Fasting glucose, HbA1c, or oral glucose tolerance testing for the detection of glucose abnormalities in patients with acute coronary syndromes.

Background: Due to the negative prognostic impact, it is important to accurately detect undiagnosed glucose perturbations in patients with acute coronary syndromes (ACS).

Methods: This study compares oral glucose tolerance test (OGTT) to fasting plasma glucose (FPG) and HbA1c as screening tools. Methods: Patients hospitalized for ACS had an OGTT, FPG, and HbA1c measured 4-21 (median 6) days after admission as a screening process for an intervention study.

Results: Out of 174 patients, 75 (43%) had a normal glucose tolerance, 63 (36%) impaired glucose tolerance (IGT), and 36 (21%) diabetes type 2 (T2DM). Of these, 20 were non-eligible, and of the remaining 79 patients, 52 had IGT and 27 T2DM according to the OGTT. In patients with IGT, the median FPG was 6.0 mmol/l and the median HbA1c was 39 mmol/mol. The corresponding levels in patients with T2DM were 6.3 mmol/l and 41 mmol/mol, respectively. Seventeen of the 27 patients with T2DM according to OGTT had not been disclosed if the screening had been based on FPG. HbA1c identified two patients.

Conclusions: Compared to OGTT, the use of FPG or HbA1c alone leaves a majority of patients with IGT or T2DM undetected when screening for unknown glucose perturbations as a part of total risk assessment of patients with ACS.