Admission hyperglycemia in AMI patients may indicate developing or unrecognized diabetes

Hyperglycemia at hospital admission for acute myocardial infarction (AMI) may indicate developing or unrecognized diabetes in patients with no history of the condition, according to a new study.

Researchers studied a national cohort of consecutive patients admitted to 127 Veterans Affairs (VA) hospitals with AMI but no known diabetes from October 2005 to March 2011. Patients were determined to have signs of diabetes at discharge or 6 months after discharge based on diagnostic codes, medication prescriptions, and elevated hemoglobin A1c values. The study authors used regression modeling to examine the association between hyperglycemia at admission (defined as a serum glucose level above 140 mg/dL) and later evidence of diabetes. Results were published early online on Oct. 2 by Diabetes Care.

A total of 10,499 patients, 98% of them men, were admitted to VA hospitals with AMI but no known diabetes. Of these, 1,761 (16.8%) had hyperglycemia at admission. This group was more likely than those without admission hyperglycemia to be older than 65, to present with a diagnosis of ST-elevation MI, and to have a TIMI (Thrombolysis in Myocardial Infarction) risk score greater than 3. Six months after the index hospitalization, 208 (11.8%) patients with admission hyperglycemia and 443 (5.1%) without had new evidence of diabetes (P<0.001).

Of these 651 patients, 169 (26.0%) had new evidence of diabetes before discharge and the remainder had new evidence in the 6 months afterward. Seventy-one patients whose diabetes was diagnosed before discharge (46.7%) had hyperglycemia at admission. In addition, 267 of the 651 patients with new evidence of diabetes (41%) had a hemoglobin A1c level of 6.5% or greater but no related diagnostic codes or prescriptions, which suggested that their diabetes was unrecognized. A significant association was seen between admission hyperglycemia and subsequent diabetes after multivariable adjustment (odds ratio, 2.56; 95% CI, 2.15 to 3.06).

The authors noted that their results may not be generalizable because the study was conducted in a mostly male population of U.S. veterans cared for in the VA health system. They also pointed out that their study was observational and retrospective, that the prevalence of diabetes may have been underestimated and that some diabetic diagnoses at admission may have been incorrect, among other limitations. However, they concluded that 1 out of 6 patients with AMI but no known diabetes had admission hyperglycemia, which was in turn associated with a 2.5-fold higher risk for evidence of diabetes in the 6 months after hospitalization.

“In addition, a significant number of these patients may have unrecognized diabetes and thus represent an important opportunity to appropriately identify and treat them,” they wrote. “Accordingly, systematic screening for diabetes among hyperglycemic AMI patients may provide opportunities for prompt identification, improved risk-stratification, institution of optimal diabetes and AMI treatments, and improved outcomes.”