The Impact of Routine HbA1c Screening on the Prevalence of Diabetes Mellitus and Outcomes in Patients Undergoing Percutaneous Coronary Intervention

Introduction: The reported rate of Diabetes Mellitus (DM) in patients undergoing Percutaneous Coronary Intervention (PCI) is 30%-40%. In 2008, the International Expert Committee recommended diabetes diagnosis by HbA1c level ≥6.5%. Our aim was to determine the prevalence of previously undiagnosed DM defined by elevated HbA1c in patients undergoing PCI and its association with 1-year clinical outcomes.
Methods: Consecutive patients undergoing PCI in a large tertiary teaching hospital were enrolled (2011-2013). HbA1c was measured before angiography. The primary outcome was 1-year Major Adverse Cardio- and Cerebrovascular Event (MACCE) defined as death, stroke, PCI or acute MI. Secondary outcomes included short term mortality.

Results: 1313 patients were enrolled (795 with ACS). DM was previously known in 528 (40.2%) patients, 232 (17.7%) had Undiagnosed DM (UDM) based on the HbA1c ≥6.5% and 553 (42.1%) did not have diabetes (Non-DM). In patients with DM HbA1c was 8.0±1.8% as compared 7.6±1.4% in patients UDM (p=0.003). UDM patients were younger (64±11) compared to DM (69±11) and non-DM (64.5±13), p<0.001. In-hospital mortality was 0.9%, 4% and 3.4% in non-DM, DM and UDM patients, respectively (p=0.004). One-year MACCE rates were 18%, 28%, and 19% in non-DM, DM, and UDM groups, respectively (p<0.001). Multivariate analysis showed that compared to non-DM (reference), the DM and UDM groups had MACCE hazard ratios of 2.11 (p<0.001) and 1.06 (p=0.55) adjusted for age, gender, smoking, previous ischemic heart disease and acute coronary syndrome.
Conclusions: Pre-procedure HbA1c testing leads to the diagnosis of previously unknown DM in a large subgroup of patients undergoing PCI. These patients represent an intermediate group as their short term mortality resembles that of patients with DM while 1-year MACCE rates are similar to non-DM patients, possibly reflecting early detection and treatment. Our findings support routine screening for DM in all patients undergoing PCI.