Background
Elevated blood glucose levels on admission are associated with increased mortality in patients with acute myocardial infarction. Whether glucose normalization after admission is associated with improved survival remains controversial. In addition, whether outcomes differ in patients who have spontaneous resolution of hyperglycemia vs those who achieve normoglycemia after treatment with insulin is also unknown.
Methods
We studied 7820 hyperglycemic (admission glucose level, ≥140 mg/dL [to convert glucose to millimoles per liter, multiply by 0.0555]) patients with acute myocardial infarction hospitalized between January 1, 2000, and December 31, 2005, in 40 US hospitals. Patients were stratified according to their mean glucose levels after admission and were divided into those who did and did not receive insulin therapy. Multivariable logistic regression models were developed to examine whether lower glucose levels after admission are independently associated with better survival. Propensity-matching methods were then used to compare in-hospital mortality in patients who did and did not receive insulin therapy.
Results
After multivariable adjustment, lower mean postadmission glucose levels were associated with better survival (for mean postadmission glucose levels of 110 to <140, 140 to <170, 170 to <200, and ≥200 mg/dL, the odds ratios [95% confidence intervals] were 2.1 [1.3-3.5], 5.3 [3.0-8.6], 6.9 [4.1-11.4], and 13.0 [8.0-21.3], respectively, vs <110 mg/dL). Similar results were seen in patients who did and did not receive insulin therapy (P =.74 for insulin therapy × postadmission glucose level interaction). In propensity-matched analysis, mortality rates were similar between insulin-treated and non–insulin-treated patients across the spectrum of mean postadmission glucose levels (range, P = .15 to P = .91).
Conclusions
Glucose normalization after admission is associated with better survival in hyperglycemic patients hospitalized with acute myocardial infarction whether or not they receive insulin therapy. A strategy of intentional glucose lowering with insulin therapy needs to be further tested in future randomized controlled trials.