Background: Acute hyperglycemia (AHG) is associated with mortality in patients with acute coronary syndrome (ACS). The extent to which hyperproinsulinemia contributes to worse clinical outcomes for this specific patient population is unknown.
Methods: We included 308 consecutive ACS patients who underwent coronary angioplasty in this pilot observational study. Patients were separated into 3 groups: patients with proven diabetes mellitus (DM group) (n =55), nondiabetic patients with a normal glucose concentration at admission (NAG group) (n =175), and nondiabetic patients with AHG at presentation (AHG group) (n =78). Blood samples for glucose, insulin, and proinsulin measurements were obtained at admission. The primary end point of the study was all-cause mortality, which was assessed at a mean follow-up of 19 months (interquartile range, 12-28 months).
Results: Patients in the AHG and DM groups had significantly (P =0.048) higher all-cause mortality compared with the NAG group. A univariate Cox regression analysis revealed that the proinsulin concentration was significantly associated with all-cause mortality for all study participants (hazard ratio, 1.013; 95% CI, 1.002-1.024; P =0.023). AHG patients with increased proinsulin concentrations showed a mortality rate similar to that of DM patients but had a significantly higher mortality rate than patients with AHG and a low proinsulin concentration (χ² =7.57; P =0.006) and patients with NAG (with or without increased proinsulin) [χ² =7.66 (P =0.006) and 13.98 (P < 0.001), respectively]. A multivariate regression analysis revealed that the concentrations of glucose and proinsulin at admission were significant (P =0.002) predictors of all-cause mortality.
Conclusions: An increased proinsulin concentration may be a marker for mortality in ACS patients with hyperglycemia at admission and without known diabetes. Further studies are needed to evaluate the role of metabolic parameters such as proinsulin.