Hyperglycemia in patients referred for cardiac catheterization is associated with preexisting diabetes rather than a stress-related phenomenon: A prospective cross-sectional study

Background An increased serum glucose level in patients with acute coronary syndrome (ACS) is associated with adverse clinical outcome. This hyperglycemia has been attributed, at least in part, to acute stress reaction. Our objective was to determine whether hyperglycemia is a stress-related phenomenon or whether it represents a more sustained and possibly significant background dysglycemia. Hypothesis Hyperglycemia in patients undergoing coronary angiography is related to background dysglycemia. Methods Blood samples were obtained at the time of cardiac catheterization. Patients with hemoglobin A1c >6.5% were excluded to avoid patients with chronic glucose levels above 135 mg/dL. A logistic regression model was created to assess the influence of different variables on hyperglycemia (glucose levels above 140 mg/dL). We also evaluated the effect of glucose levels above 140 mg/dL on major adverse cardiovascular events (MACEs) up to 36 months. Results There were 2554 consecutive patients prospectively recruited. Serum glucose levels above 140 mg/dL was a strong predictor of MACE (hazard ratio: 2.2, 95% confidence interval [CI]: 1.3-3.6, P = 0.002). Both diabetes mellitus and ACS were associated with hyperglycemia (glucose levels above 140 mg/dL). Nevertheless, the incidence of hyperglycemia was doubled in diabetic patients (odds ratio [OR]: 9.4, 95% CI: 3.9-22.4, P < 0.001) compared with patients with ACS (OR: 4.6, 95% CI: 2.3-9.0, P < 0.001). Combining both conditions was associated with a high likelihood of elevated glucose levels (OR: 15.5, 95% CI: 7.4-32.9, P < 0.001). Conclusions Hyperglycemia in patients undergoing cardiac catheterization is a strong predictor of adverse outcome. It is mainly related to background dysglycemia and to a lesser extent to the acute stress accompanying ACS.